Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - QUALITY OF SERVICE CONFIGURATION GUIDE 2010-09-22, JUNOSE 11.3 Configuration Manual

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JunosE™ Software for E Series™ Broadband Services Routers

Quality of Service Configuration Guide

Release

11.3.x

Published: 2010-09-22

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Juniper Networks, Inc. 1194 North Mathilda Avenue Sunnyvale, California 94089 USA 408-745-2000 www.juniper.net

Juniper Networks, Junos, Steel-Belted Radius, NetScreen, and ScreenOS are registered trademarks of Juniper Networks, Inc. in the United States and other countries. The Juniper Networks Logo, the Junos logo, and JunosE are trademarks of Juniper Networks, Inc. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.

Juniper Networks assumes no responsibility for any inaccuracies in this document. Juniper Networks reserves the right to change, modify, transfer, or otherwise revise this publication without notice.

Products made or sold by Juniper Networks or components thereof might be covered by one or more of the following patents that are owned by or licensed to Juniper Networks: U.S. Patent Nos. 5,473,599, 5,905,725, 5,909,440, 6,192,051, 6,333,650, 6,359,479, 6,406,312, 6,429,706, 6,459,579, 6,493,347, 6,538,518, 6,538,899, 6,552,918, 6,567,902, 6,578,186, and 6,590,785.

JunosE™ Software for E Series™ Broadband Services Routers Quality of Service Configuration Guide

Writing: Krupa Chandrashekar, Bruce Gillham, Sarah Lesway-Ball, Brian Wesley Simmons, Poornima Goswami, Chander Aima, Namrata Mehta Editing: Benjamin Mann Illustration: Nathaniel Woodward Cover Design: Edmonds Design

Revision History October 2010—FRS JunosE 11.3.x

The information in this document is current as of the date listed in the revision history.

YEAR 2000 NOTICE

Juniper Networks hardware and software products are Year 2000 compliant. The Junos OS has no known time-related limitations through the year 2038. However, the NTP application is known to have some difficulty in the year 2036.

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END USER LICENSE AGREEMENT

READ THIS END USER LICENSE AGREEMENT (“AGREEMENT”) BEFORE DOWNLOADING, INSTALLING, OR USING THE SOFTWARE.

BY DOWNLOADING, INSTALLING, OR USING THE SOFTWARE OR OTHERWISE EXPRESSING YOUR AGREEMENT TO THE TERMS CONTAINED HEREIN, YOU (AS CUSTOMER OR IF YOU ARE NOT THE CUSTOMER, AS A REPRESENTATIVE/AGENT AUTHORIZED TO BIND THE CUSTOMER) CONSENT TO BE BOUND BY THISAGREEMENT. IF YOU DO NOTOR CANNOT AGREE TO THE TERMSCONTAINED HEREIN, THEN (A) DO NOT DOWNLOAD, INSTALL, OR USE THE SOFTWARE, AND (B) YOU MAY CONTACT JUNIPER NETWORKS REGARDING LICENSE TERMS.

1. The Parties. The parties to this Agreement are (i) Juniper Networks, Inc. (if the Customer’s principal office is located in the Americas) or Juniper Networks(Cayman)Limited(if the Customer’s principaloffice is locatedoutside the Americas) (such applicable entity beingreferred to herein as“Juniper”), and (ii)the person ororganizationthat originally purchased from Juniperor an authorized Juniper reseller the applicable license(s) for use of the Software (“Customer”) (collectively, the “Parties”).

2. The Software. In this Agreement, “Software” means the program modules and features of the Juniper or Juniper-supplied software, for which Customer has paid the applicable license or support fees to Juniper or an authorized Juniper reseller, or which was embedded by Juniper in equipment which Customer purchased from Juniper or an authorized Juniper reseller. “Software” also includes updates, upgrades and new releases of such software. “Embedded Software” means Software which Juniper has embedded in or loaded onto the Juniper equipment and any updates, upgrades, additions or replacements which are subsequently embedded in or loaded onto the equipment.

3. License Grant. Subject to payment of the applicablefeesand the limitations andrestrictions set forthherein, Juniper grantsto Customer a non-exclusive and non-transferable license, without right to sublicense, to use the Software, in executable form only, subject to the following use restrictions:

a. Customer shall use Embedded Software solely as embedded in, and for execution on, Juniper equipment originally purchased by Customer from Juniper or an authorized Juniper reseller.

b. Customer shall use the Software on a single hardware chassis having a single processing unit, or as many chassis or processing units for which Customer has paid the applicable license fees; provided, however, with respect to the Steel-Belted Radius or Odyssey Access Client software only, Customer shall use such Software on a single computer containing a single physical random access memory space and containing any number of processors. Use of the Steel-Belted Radius or IMS AAA software on multiple computers or virtual machines (e.g., Solaris zones) requires multiple licenses, regardless of whether such computers or virtualizations are physically contained on a single chassis.

c. Product purchase documents, paper or electronic user documentation, and/or the particular licenses purchased by Customer may specify limitstoCustomer’suse ofthe Software.Such limitsmay restrict use toa maximum number of seats, registeredendpoints, concurrent users, sessions, calls, connections, subscribers, clusters, nodes, realms, devices, links, ports or transactions, or require the purchase of separate licenses to use particular features, functionalities, services, applications, operations, or capabilities, or provide throughput, performance, configuration, bandwidth, interface, processing, temporal, or geographical limits. In addition, such limits may restrict the use of the Software to managing certain kinds of networks or require the Software to be used only in conjunction with other specific Software. Customer’s use of the Software shall be subject to all such limitations and purchase of all applicable licenses.

d. For any trial copy of the Software, Customer’s right to use the Software expires 30 days after download, installation or use of the Software. Customer may operate the Software after the 30-day trial period only if Customer pays for a license to do so. Customer may not extend or create an additional trial period by re-installing the Software after the 30-day trial period.

e. The Global Enterprise Edition of the Steel-Belted Radius software may be used by Customer only to manage access to Customer’s enterprise network. Specifically, service provider customers are expressly prohibited from using the Global Enterprise Edition of the Steel-Belted Radius software to support any commercial network access services.

The foregoing license is not transferable or assignable by Customer. No license is granted herein to any user who did not originally purchase the applicable license(s) for the Software from Juniper or an authorized Juniper reseller.

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Software in any manner that extends or is broader than the uses purchased by Customer from Juniper or an authorized Juniper reseller; (i) use Embedded Software on non-Juniper equipment; (j) use Embedded Software (or make it available for use) on Juniper equipment that the Customer did not originally purchase from Juniper or an authorized Juniper reseller; (k) disclose the results of testing or benchmarking of the Software to any third party without the prior written consent of Juniper; or (l) use the Software in any manner other than as expressly provided herein.

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8. Warranty, Limitation of Liability, Disclaimer of Warranty. The warranty applicable to the Software shall be as set forth in the warranty statementthataccompaniesthe Software (the “Warranty Statement”). Nothing inthis Agreement shallgive rise to anyobligation tosupport the Software. Support services may be purchased separately. Any such support shall be governed by a separate, written support services agreement. TO THE MAXIMUM EXTENT PERMITTED BY LAW, JUNIPER SHALL NOT BE LIABLE FOR ANY LOST PROFITS, LOSS OF DATA, OR COSTS ORPROCUREMENT OFSUBSTITUTE GOODSOR SERVICES,OR FORANYSPECIAL,INDIRECT, ORCONSEQUENTIALDAMAGES ARISING OUTOF THIS AGREEMENT,THE SOFTWARE,OR ANY JUNIPEROR JUNIPER-SUPPLIED SOFTWARE. IN NOEVENT SHALL JUNIPER BE LIABLE FOR DAMAGES ARISING FROM UNAUTHORIZED OR IMPROPER USE OF ANY JUNIPER OR JUNIPER-SUPPLIED SOFTWARE. EXCEPT AS EXPRESSLY PROVIDED IN THE WARRANTY STATEMENT TO THE EXTENT PERMITTED BY LAW, JUNIPER DISCLAIMS ANY AND ALL WARRANTIES IN AND TO THE SOFTWARE (WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE), INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NONINFRINGEMENT. IN NO EVENT DOES JUNIPER WARRANT THAT THE SOFTWARE, OR ANY EQUIPMENT OR NETWORK RUNNING THE SOFTWARE, WILL OPERATE WITHOUT ERROR OR INTERRUPTION, OR WILL BE FREE OF VULNERABILITY TO INTRUSION OR ATTACK. In no event shall Juniper’s or its suppliers’ or licensors’ liability to Customer, whether in contract, tort (including negligence), breach of warranty, or otherwise, exceed the price paid by Customer for the Software that gave rise to the claim, or if the Software is embedded in another Juniper product, the price paid by Customer for such other product. Customer acknowledges and agrees that Juniper has set its prices and entered into this Agreement in reliance upon the disclaimers of warranty and the limitations of liability set forth herein, that the same reflect an allocation of risk between the Parties (including the risk that a contract remedy may fail of its essential purpose and cause consequential loss), and that the same form an essential basis of the bargain between the Parties.

9. Termination. Any breach of this Agreement or failure by Customer to pay any applicable fees due shall result in automatic termination of the license granted herein. Upon such termination, Customer shall destroy or return to Juniper all copies of the Software and related documentation in Customer’s possession or control.

10. Taxes. All license fees payable under this agreement are exclusive of tax. Customer shall be responsible for paying Taxes arising from the purchase of the license, or importation or use of the Software. If applicable, valid exemption documentation for each taxing jurisdiction shall be provided to Juniper prior to invoicing, and Customer shall promptly notify Juniper if their exemption is revoked or modified. All payments made by Customer shall be net of any applicable withholding tax. Customer will provide reasonable assistance to Juniper in connection with such withholding taxes by promptly: providing Juniper with valid tax receipts and other required documentation showing Customer’s payment of any withholding taxes; completing appropriate applications that would reduce the amount of withholding tax to be paid; and notifying and assisting Juniper in any audit or tax proceeding related to transactions hereunder. Customer shall comply with all applicable tax laws and regulations, and Customer will promptly pay or reimburse Juniper for all costs and damages related to any liability incurred by Juniper as a result of Customer’s non-compliance or delay with its responsibilities herein. Customer’s obligations under this Section shall survive termination or expiration of this Agreement.

11. Export. Customer agrees to comply with all applicable export laws and restrictions and regulations of any United States and any applicable foreign agency or authority, and not to export or re-export the Software or any direct product thereof in violation of any such restrictions, laws or regulations, or without all necessary approvals. Customer shall be liable for any such violations. The version of the Software supplied to Customer may contain encryption or other capabilities restricting Customer’s ability to export the Software without an export license.

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12. Commercial Computer Software. The Software is “commercial computer software” and is provided with restricted rights. Use, duplication, or disclosure by the United States government is subject to restrictions set forth in this Agreement and as provided in DFARS

227.7201 through 227.7202-4, FAR 12.212, FAR 27.405(b)(2), FAR 52.227-19, or FAR 52.227-14(ALT III) as applicable.

13. Interface Information. To the extent required by applicable law, and at Customer's written request, Juniper shall provide Customer with the interface information needed to achieve interoperability between the Software and another independently created program, on payment of applicable fee, if any. Customer shall observe strict obligations of confidentiality with respect to such information and shall use such information in compliance with any applicable terms and conditions upon which Juniper makes such information available.

14. Third Party Software. Any licensor of Juniper whose software is embeddedin the Software and any supplier of Juniper whose products or technology are embedded in (or services are accessed by) the Software shall be a third party beneficiary with respect to this Agreement, and such licensor or vendor shallhave theright to enforce this Agreement in its own nameas if it were Juniper. In addition, certain third party software may be provided with the Software and is subject to the accompanying license(s), if any, of its respective owner(s). To the extent portions of the Software are distributed under and subject to open source licenses obligating Juniper to make the source code for such portions publicly available (such as the GNU General Public License (“GPL”) or the GNU Library General Public License (“LGPL”)), Juniper will make such source code portions (including Juniper modifications, as appropriate) available upon request for a period of up to three years from the date of distribution. Such request can be made in writing to Juniper Networks, Inc., 1194 N. Mathilda Ave., Sunnyvale, CA 94089, ATTN: General Counsel. You may obtain a copy of the GPL at http://www.gnu.org/licenses/gpl.html, and a copy of the LGPL

at http://www.gnu.org/licenses/lgpl.html .

15. Miscellaneous. This Agreement shall be governed by the laws of the State of California without reference to its conflicts of laws principles. The provisions of the U.N. Convention for the International Sale of Goods shall not apply to this Agreement. For any disputes arising under this Agreement, the Parties hereby consent to the personal and exclusive jurisdiction of, and venue in, the state and federal courts within Santa Clara County, California. This Agreement constitutes the entire and sole agreement between Juniper and the Customer with respect to the Software, and supersedes all prior and contemporaneous agreements relating to the Software, whether oral or written (including any inconsistent terms contained in a purchase order), except that the terms of a separate written agreement executed by an authorized Juniper representative and Customer shall govern to the extent such terms are inconsistent or conflict with terms contained herein. No modification to this Agreement nor any waiver of any rights hereunder shall be effective unless expressly assented to in writing by the party to be charged. If any portion of this Agreement is held invalid, the Parties agree that such invalidity shall not affect the validity of the remainder of this Agreement. This Agreement and associated documentation has been written in the English language, and the Parties agree that the English version will govern. (For Canada: Les parties aux présentés confirment leur volonté que cette convention de même que tous les documents y compris tout avis qui s'y rattaché, soient redigés en langue anglaise. (Translation: The parties confirm that this Agreement and all related documentation is and will be in the English language)).

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Abbreviated Table of Contents

About the Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxvii

Part 1 QoS on the E Series Router

Chapter 1 Quality of Service Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Part 2 Classifying, Queuing, and Dropping Traffic

Chapter 2 Defining Service Levels with Traffic Classes and Traffic-Class Groups . . . . 13

Chapter 3 Configuring Queue Profiles for Buffer Management . . . . . . . . . . . . . . . . . . . . 17

Chapter 4 Configuring Dropping Behavior with RED and WRED . . . . . . . . . . . . . . . . . . . 25

Chapter 5 Gathering Statistics for Rates and Events in the Queue . . . . . . . . . . . . . . . . 37

Part 3 Scheduling and Shaping Traffic

Chapter 6 QoS Scheduler Hierarchy Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Chapter 7 Configuring Rates and Weights in the Scheduler Hierarchy . . . . . . . . . . . . . . 51

Chapter 8 Configuring Strict-Priority Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Chapter 9 Shared Shaping Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Chapter 10 Configuring Simple Shared Shaping of Traffic . . . . . . . . . . . . . . . . . . . . . . . . 75

Chapter 11 Configuring Variables in the Simple Shared Shaping Algorithm . . . . . . . . . 85

Chapter 12 Configuring Compound Shared Shaping of Traffic . . . . . . . . . . . . . . . . . . . . 95

Chapter 13 Configuring Implicit and Explicit Constituent Selection for Shaping . . . . 103

Chapter 14 Monitoring a QoS Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Part 4 Creating a QoS Scheduler Hierarchy on an Interface with QoS

Profiles

Chapter 15 QoS Profile Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Chapter 16 Configuring and Attaching QoS Profiles to an Interface . . . . . . . . . . . . . . . . 125

Chapter 17 Configuring Shadow Nodes for Queue Management . . . . . . . . . . . . . . . . . . 141

Chapter 18 Monitoring a Scheduler Hierarchy on an Interface with QoS Profiles . . . . 147

Part 5 Interface Solutions for QoS

Chapter 19 Configuring an Integrated Scheduler to Provide QoS for ATM . . . . . . . . . . . 151

Chapter 20 Configuring QoS for Gigabit Ethernet Interfaces and VLAN

Subinterfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

Chapter 21 Configuring QoS for 802.3ad Link Aggregation Groups . . . . . . . . . . . . . . . . 175

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JunosE 11.3.x Quality of Service Configuration Guide

Chapter 22 Configuring QoS for L2TP Sessions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Chapter 23 Configuring Interface Sets for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Part 6 Managing Queuing and Scheduling with QoS Parameters

Chapter 24 QoS Parameter Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

Chapter 25 Configuring a QoS Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Chapter 26 Configuring Hierarchical QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

Chapter 27 Configuring IP Multicast Bandwidth Adjustment with QoS Parameters . . 253

Chapter 28 Configuring the Shaping Mode for Ethernet with QoS Parameters . . . . . 265

Chapter 29 Configuring Byte Adjustment for Shaping Rates with QoS Parameters . . 275

Chapter 30 Configuring the Downstream Rate Using QoS Parameters . . . . . . . . . . . . 283

Part 7 Monitoring and Troubleshooting QoS

Chapter 31 Monitoring QoS on E Series Routers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

Chapter 32 Troubleshooting QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

Part 8 Index

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

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Table of Contents

About the Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxvii

E Series and JunosE Documentation and Release Notes . . . . . . . . . . . . . . . . . . xxvii

Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxvii

E Series and JunosE Text and Syntax Conventions . . . . . . . . . . . . . . . . . . . . . . . xxvii

Obtaining Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxix

Documentation Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxix

Requesting Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxix

Self-Help Online Tools and Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxx

Opening a Case with JTAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxx

Part 1 QoS on the E Series Router

Chapter 1 Quality of Service Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

QoS on the E Series Router Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

QoS Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

QoS Platform Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Interface Specifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

QoS Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

QoS Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Configuring QoS on the E Series Router . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

QoS References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Part 2 Classifying, Queuing, and Dropping Traffic

Chapter 2 Defining Service Levels with Traffic Classes and Traffic-Class Groups . . . . 13

Traffic Class and Traffic-Class Groups Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Best-Effort Forwarding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Traffic-Class Groups Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Configuring Traffic Classes That Define Service Levels . . . . . . . . . . . . . . . . . . . . . . 14

Configuring Traffic-Class Groups That Define Service Levels . . . . . . . . . . . . . . . . . 15

Monitoring Traffic Classes and Traffic-Class Groups for Defined Levels of

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Chapter 3 Configuring Queue Profiles for Buffer Management . . . . . . . . . . . . . . . . . . . . 17

Queuing and Buffer Management Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Static Oversubscription . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Dynamic Oversubscription . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

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JunosE 11.3.x Quality of Service Configuration Guide

Color-Based Thresholding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Memory Requirements for Queue and Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Guidelines for Managing Queue Thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Guidelines for Configuring a Maximum Threshold . . . . . . . . . . . . . . . . . . . . . . 19

Guidelines for Configuring a Minimum Threshold . . . . . . . . . . . . . . . . . . . . . . 20

Guidelines for Managing Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Guidelines for Managing Buffer Starvation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Configuring Queue Profiles to Manage Buffers and Thresholds . . . . . . . . . . . . . . . 22

Monitoring Queues and Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Chapter 4 Configuring Dropping Behavior with RED and WRED . . . . . . . . . . . . . . . . . . . 25

Dropping Behavior Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

RED and WRED Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Configuring RED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Example: Configuring Average Queue Length for RED . . . . . . . . . . . . . . . . . . . . . . 28

Example: Configuring Dropping Thresholds for RED . . . . . . . . . . . . . . . . . . . . . . . 28

Example: Configuring Color-Blind RED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Configuring WRED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Example: Configuring Different Treatment of Colored Packets for WRED . . . . . . . 32

Example: Defining Different Drop Behavior for Each Traffic Class for WRED . . . . 32

Example: Configuring WRED and Dynamic Queue Thresholds . . . . . . . . . . . . . . . 33

Monitoring RED and WRED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Chapter 5 Gathering Statistics for Rates and Events in the Queue . . . . . . . . . . . . . . . . 37

QoS Statistics Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Rate Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Event Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Bulk Statistics Support for QoS Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Configuring Statistic Profiles for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Configuring Rate Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Configuring Event Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Clearing QoS Statistics on the Egress Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Clearing QoS Statistics on the Fabric Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Monitoring QoS Statistics for Rates and Events . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Part 3 Scheduling and Shaping Traffic

Chapter 6 QoS Scheduler Hierarchy Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Scheduler Hierarchy Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Configuring a Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Configuring a Scheduler Profile for a Scheduler Node or Queue . . . . . . . . . . . . . . 48

Using Expressions for Bandwidth and Burst Values in a Scheduler Profile . . . . . . 48

Shaping Rates, Assured Rates, and Relative Weights in a Scheduler

Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

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Chapter 7 Configuring Rates and Weights in the Scheduler Hierarchy . . . . . . . . . . . . . . 51

Rate Shaping and Port Shaping Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Configuring Rate Shaping for a Scheduler Node or Queue . . . . . . . . . . . . . . . . . . . 52

Configuring Port Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Static and Hierarchical Assured Rate Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Configuring an Assured Rate for a Scheduler Node or Queue . . . . . . . . . . . . . . . . 54

Configuring a Static Assured Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Configuring a Hierarchical Assured Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Changing the Assured Rate to an HRR Weight . . . . . . . . . . . . . . . . . . . . . . . . 55

Configuring the HRR Weight for a Scheduler Node or Queue . . . . . . . . . . . . . . . . 56

Chapter 8 Configuring Strict-Priority Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Strict-Priority and Relative Strict-Priority Scheduling Overview . . . . . . . . . . . . . . 57

Relative Strict-Priority Scheduling Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Comparison of True Strict Priority with Relative Strict Priority Scheduling . . . . . . 59

Schedulers and True Strict Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Schedulers and Relative Strict Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Relative Strict Priority on ATM Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Oversubscribing ATM Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Minimizing Latency on the SAR Scheduler . . . . . . . . . . . . . . . . . . . . . . . . 61

HRR Scheduler Behavior and Strict-Priority Scheduling . . . . . . . . . . . . . . . . . 61

Zero-Weight Queues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Setting the Burst Size in a Shaping Rate . . . . . . . . . . . . . . . . . . . . . . . . . 62

Special Shaping Rate for Nonstrict Queues . . . . . . . . . . . . . . . . . . . . . . . 62

Configuring Strict-Priority Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Configuring Relative Strict-Priority Scheduling for Aggregate Shaping Rates . . . . 65

Chapter 9 Shared Shaping Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Shared Shaping Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Shared Shaper Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

How Shared Shaping Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Active Constituents for Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Guidelines for Configuring Simple and Compound Shared Shaping . . . . . . . . . . . 70

Shared Shaping and Individual Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Shared Shaping and Best-Effort Queues and Nodes . . . . . . . . . . . . . . . . . . . 70

ATM and Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Sharing Bandwidth with the SAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Shared Shaping and Low-CDV Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Logical Interface Traffic Carried in Other Queues . . . . . . . . . . . . . . . . . . . . . . 72

Traffic Starvation and Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Oversubscription and Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Burst Size and Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Chapter 10 Configuring Simple Shared Shaping of Traffic . . . . . . . . . . . . . . . . . . . . . . . . 75

Simple Shared Shaping Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Bandwidth Allocation for Simple Shared Shaping . . . . . . . . . . . . . . . . . . . . . 75

Simple Shared Shaping on the Best-Effort Scheduler Node . . . . . . . . . . . . . 75

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Simple Shared Shaping for Triple-Play Networks . . . . . . . . . . . . . . . . . . . . . . 76

Configuring Simple Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Example: Simple Shared Shaping for ATM VCs . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Example: Simple Shared Shaping for ATM VPs . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Example: Simple Shared Shaping for Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Chapter 11 Configuring Variables in the Simple Shared Shaping Algorithm . . . . . . . . . 85

Simple Shared Shaping Algorithm Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Simple Shared Shaper Algorithm Calculations . . . . . . . . . . . . . . . . . . . . . . . . 86

Variables of the Simple Shared Shaper Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . 87

Guidelines for Controlling the Simple Shared Shaper Algorithm . . . . . . . . . . . . . 88

Configuring Simple Shared Shaper Algorithm Variables . . . . . . . . . . . . . . . . . . . . 89

Sample Process for Controlling the Simple Shared Shaper Algorithm . . . . . . . . . 90

Chapter 12 Configuring Compound Shared Shaping of Traffic . . . . . . . . . . . . . . . . . . . . 95

Compound Shared Shaping Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Supported Hardware for Compound Shared Shaping . . . . . . . . . . . . . . . . . . 95

Bandwidth Allocation for Compound Shared Shaping . . . . . . . . . . . . . . . . . . 96

Configuring Compound Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Example: Compound Shared Shaping for ATM VCs . . . . . . . . . . . . . . . . . . . . . . . . 98

Example: Compound Shared Shaping for ATM VPs . . . . . . . . . . . . . . . . . . . . . . . 100

Chapter 13 Configuring Implicit and Explicit Constituent Selection for Shaping . . . . 103

Constituent Selection for Shared Shaping Overview . . . . . . . . . . . . . . . . . . . . . . 103

Types of Shared Shaper Constituents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

Implicit Constituent Selection Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Implicit Bandwidth Allocation for Compound Shared Shaping . . . . . . . . . . . 107

Weighted Compound Shared Shaping Example . . . . . . . . . . . . . . . . . . 109

Configuring Implicit Constituents for Simple or Compound Shared Shaping . . . 110

Explicit Constituent Selection Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Explicit Shared Shaping Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Explicit Weighted Compound Shared Shaping Example . . . . . . . . . . . . . . . . 112

Configuring Explicit Constituents for Simple or Compound Shared Shaping . . . . 115

Chapter 14 Monitoring a QoS Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Monitoring QoS Scheduling and Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Part 4 Creating a QoS Scheduler Hierarchy on an Interface with QoS

Profiles

Chapter 15 QoS Profile Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

QoS Profile Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Managing System Resources for Nodes and Queues . . . . . . . . . . . . . . . . . . . . . . . 121

Scaling Subscribers on the TFA ASIC with QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Chapter 16 Configuring and Attaching QoS Profiles to an Interface . . . . . . . . . . . . . . . . 125

Supported Interface Types for QoS Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Configuring a QoS Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

Attaching a QoS Profile to an Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

Attaching a QoS Profile to a Base Interface . . . . . . . . . . . . . . . . . . . . . . . . . . 128

Attaching a QoS Profile to an ATM VP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

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Attaching a QoS Profile to an S-VLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

Attaching a QoS Profile to a Port Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

Munged QoS Profile Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Sample Munged QoS Profile Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Example: Port-Type QoS Profile Attachment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

Example: QoS Profile Attachment to Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

Example: Diffserv Configuration with Multiple Traffic-Class Groups . . . . . . . . . . 137

Chapter 17 Configuring Shadow Nodes for Queue Management . . . . . . . . . . . . . . . . . . 141

Shadow Node Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

Shadow Nodes and Scheduler Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

Managing System Resources for Shadow Nodes . . . . . . . . . . . . . . . . . . . . . . . . . 143

Configuring Shadow Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

Example: Shadow Nodes over VLAN and IP Queues . . . . . . . . . . . . . . . . . . . . . . 145

Example: Shadow Nodes on the Same Traffic-Class Group . . . . . . . . . . . . . . . . 146

Example: Shadow Nodes on Different Traffic-Class Groups . . . . . . . . . . . . . . . . 146

Chapter 18 Monitoring a Scheduler Hierarchy on an Interface with QoS Profiles . . . . 147

Monitoring a Scheduler Hierarchy on an Interface with QoS Profiles . . . . . . . . . . 147

Part 5 Interface Solutions for QoS

Chapter 19 Configuring an Integrated Scheduler to Provide QoS for ATM . . . . . . . . . . . 151

ATM Integrated Scheduler Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Backpressure and the Integrated Scheduler . . . . . . . . . . . . . . . . . . . . . . . . . . 152

VP Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

Integrating the HRR Scheduler and SAR Scheduler . . . . . . . . . . . . . . . . . . . . . . . 154

Per-Packet Queuing on the SAR Scheduler Overview . . . . . . . . . . . . . . . . . . . . . . 155

Operational QoS Shaping Mode for ATM Interfaces Overview . . . . . . . . . . . 156

ERX7xx Models, ERX14xx Models, and the ERX310 Router . . . . . . . . . . 156

E120 Router and E320 Router . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

Guidelines for Configuring QoS over ATM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

Configuring Default Integrated Mode for ATM Interface . . . . . . . . . . . . . . . . . . . . 160

Configuring Low-Latency Mode for Per-Port Queuing on ATM Interfaces . . . . . . 161

Configuring Low-CDV Mode for Per-Port Queuing on ATM Interfaces . . . . . . . . . 163

Configuring the QoS Shaping Mode for ATM Interfaces . . . . . . . . . . . . . . . . . . . . 166

Disabling Per-Port Queuing on ATM Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

Monitoring QoS Configurations for ATM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

Chapter 20 Configuring QoS for Gigabit Ethernet Interfaces and VLAN

Subinterfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

Providing QoS for Ethernet Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

QoS Shaping Mode for Ethernet Interfaces Overview . . . . . . . . . . . . . . . . . . . . . . 170

Configuring the QoS Shaping Mode for Ethernet Interfaces . . . . . . . . . . . . . . . . . 171

Creating a QoS Interface Hierarchy for Bulk-Configured VLAN Subinterfaces

with RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

Monitoring QoS Configurations for Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

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Chapter 21 Configuring QoS for 802.3ad Link Aggregation Groups . . . . . . . . . . . . . . . . 175

QoS for 802.3ad Link Aggregation Interfaces Overview . . . . . . . . . . . . . . . . . . . . 175

Types of Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

Munged QoS Profiles and Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

802.3ad Link Aggregation and QoS Parameters . . . . . . . . . . . . . . . . . . . . . . 176

QoS and Ethernet Link Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

Active Link Failure and QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

Administratively Disabling a Link and QoS . . . . . . . . . . . . . . . . . . . . . . . . 177

Adding a New Link to the LAG and QoS . . . . . . . . . . . . . . . . . . . . . . . . . . 177

Hashed Load Balancing for 802.3ad Link Aggregation Groups Overview . . . . . . . 177

Sample Scheduler Hierarchy for Hashed Load Balancing . . . . . . . . . . . . . . . 178

Subscriber Load Balancing for 802.3ad Link Aggregation Groups Overview . . . . 178

S-VLANs and Subscriber Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

PPPoE over VLANs and Subscriber Load Balancing . . . . . . . . . . . . . . . . . . . 179

PPPoE over Ethernet (No VLANs) and Subscriber Load Balancing . . . . . . . 179

MPLS over LAG and Subscriber Load Balancing . . . . . . . . . . . . . . . . . . . . . . 179

Sample Scheduler Hierarchy for Subscriber Load Balancing . . . . . . . . . . . . . 179

Subscriber Allocation in 802.3ad Link Aggregation Groups . . . . . . . . . . . . . 180

Guidelines for Configuring QoS over 802.3ad Link Aggregation Groups . . . . . . . . 181

Configuring the Scheduler Hierarchy for Hashed Load Balancing in 802.3ad Link

Aggregation Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

Enabling Default Subscriber Load Balancing for 802.3ad Link Aggregation

Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

Configuring the Scheduler Hierarchy for Subscriber Load Balancing in 802.3ad

Link Aggregation Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

Configuring Load Rebalancing for 802.3ad Link Aggregation Groups . . . . . . . . . 184

Configuring Load–Rebalancing Parameters . . . . . . . . . . . . . . . . . . . . . . . . . 184

Configuring the System to Dynamically Rebalance the LAG . . . . . . . . . . . . . 185

Monitoring QoS Configurations for 802.3ad Link Aggregation Groups . . . . . . . . 186

Chapter 22 Configuring QoS for L2TP Sessions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Providing QoS for L2TP Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Sample Scheduler Hierarchies for L2TP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Configuring QoS for an L2TP Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

Configuring QoS for an L2TP LNS Session . . . . . . . . . . . . . . . . . . . . . . . . . . . 190

Configuring QoS for an L2TP LAC Session . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

Configuring QoS for Tunnel-Server Ports for L2TP LNS Sessions . . . . . . . . . . . . 192

QoS and L2TP TX Speed AVP 24 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

Logical Interfaces and Shared-Shaping Rates . . . . . . . . . . . . . . . . . . . . . . . . 193

Shaping Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

Monitoring QoS Configurations for L2TP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

Chapter 23 Configuring Interface Sets for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Interface Sets for QoS Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Interface Set Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Architecture of Interface Sets for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

Interface Set Parents and Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

Sample Interface Columns and Scheduler Hierarchies . . . . . . . . . . . . . . . . . 197

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Scheduling and Shaping Interface Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198

Configuring Interface Sets for Scheduling and Queuing . . . . . . . . . . . . . . . . . . . . 199

Configuring Interface Supersets for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

Configuring an Interface Superset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

Restricting an Interface Superset to an S-VLAN ID or an ATM VP . . . . . . . . 200

Configuring Interface Sets for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

Configuring an Interface Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

Deleting an Interface Set from an Interface Superset . . . . . . . . . . . . . . . . . . 201

Adding Member Interfaces to an Interface Set . . . . . . . . . . . . . . . . . . . . . . . . . . . 202

Adding Interfaces to an Interface Set with the CLI . . . . . . . . . . . . . . . . . . . . 202

Adding Interfaces to an Interface Set with RADIUS . . . . . . . . . . . . . . . . . . . 202

Changing and Deleting Interface Members in an Interface Set . . . . . . . . . . 203

Changing Interface Members with Upper-Layer Protocols in an Interface

Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

Creating a QoS Parameter on an Interface Superset or Interface Set . . . . . . . . . 204

Configuring a QoS Parameter Definition for an Interface Superset or an

Interface Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

Creating a QoS Parameter Instance for an Interface Superset . . . . . . . . . . . 204

Creating a QoS Parameter Instance for an Interface Set . . . . . . . . . . . . . . . 205

Attaching a QoS Profile to an Interface Superset or an Interface Set . . . . . . . . . 205

Configuring a QoS Profile for an Interface Superset or an Interface Set . . . 205

Attaching a QoS Profile to an Interface Superset . . . . . . . . . . . . . . . . . . . . . 206

Attaching a QoS Profile to an Interface Set . . . . . . . . . . . . . . . . . . . . . . . . . . 206

Deleting an Interface Superset or an Interface Set . . . . . . . . . . . . . . . . . . . . . . . . 207

Deleting an Interface Superset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

Deleting an Interface Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

Example: Configuring Interface Sets for 802.3ad Link Aggregation Groups . . . . 208

Part 6 Managing Queuing and Scheduling with QoS Parameters

Chapter 24 QoS Parameter Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

QoS Parameter Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

QoS Parameter Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

QoS Parameter Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

Relationship Among QoS Parameters, Scheduler Profiles, and QoS Profiles . . . 213

QoS Administrator Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

QoS Client Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

Chapter 25 Configuring a QoS Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Parameter Definition Attributes for QoS Administrators Overview . . . . . . . . . . . 215

Naming Guidelines for QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

Interface Types and QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

Controlled-Interface Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

Instance-Interface Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218

Subscriber-Interface Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

Range of QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

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Applications and QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220

Scheduler Profiles and Parameter Expressions for QoS Administrators . . . . . . . 221

Referencing a Parameter Definition in a Scheduler Profile . . . . . . . . . . . . . . . 221

Removing or Modifying a Scheduler Profile . . . . . . . . . . . . . . . . . . . . . . . 221

Using Expressions for QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

Operators and Precedence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222

Specifying a Range in Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

Configuring a Basic Parameter Definition for QoS Administrators . . . . . . . . . . . . 223

Parameter Instances for QoS Clients Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 225

Global QoS Parameter Instance Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 226

QoS Parameters for Interfaces Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

Creating Parameter Instances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

Creating a Global Parameter Instance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

Creating a Parameter Instance for an Interface . . . . . . . . . . . . . . . . . . . . . . . 227

Creating a Parameter Instance for an ATM VP . . . . . . . . . . . . . . . . . . . . . . . . 227

Creating a Parameter Instance for an S-VLAN . . . . . . . . . . . . . . . . . . . . . . . 228

Example: QoS Parameter Configuration for Controlling Subscriber

Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

Procedure for QoS Administrators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230

Procedure for QoS Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

Monitoring the Subscriber Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

Complete Configuration Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

QoS Administrator Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

QoS Client Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243

Chapter 26 Configuring Hierarchical QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

Hierarchical QoS Parameters Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

Guidelines for Configuring Hierarchical Parameters . . . . . . . . . . . . . . . . . . . . . . . 245

Configuring a Parameter Definition to Calculate Hierarchical Instances . . . . . . . 246

Example: QoS Parameter Configuration for Hierarchical Parameters . . . . . . . . . 247

Procedure for QoS Administrators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247

Procedure for QoS Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

Monitoring Hierarchical QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 250

Complete Configuration Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250

QoS Administrator Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250

QoS Client Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251

Chapter 27 Configuring IP Multicast Bandwidth Adjustment with QoS Parameters . . 253

IP Multicast Bandwidth Adjustment for QoS Overview . . . . . . . . . . . . . . . . . . . . 253

Guidelines for Configuring IP Multicast Adjustment for QoS . . . . . . . . . . . . . . . . 255

Configuring a Parameter Definition for IP Multicast Bandwidth Adjustment . . . 255 Example: QoS Parameter Configuration for IP Multicast Bandwidth

Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

Monitoring the Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260

Complete Configuration Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

Chapter 28 Configuring the Shaping Mode for Ethernet with QoS Parameters . . . . . 265

Cell Shaping Mode Using QoS Parameters Overview . . . . . . . . . . . . . . . . . . . . . 265

Overriding the QoS Shaping Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

Module Types and Capabilities for QoS Cell Mode Application . . . . . . . . . . 266

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Cell Tax Adjustment Using QoS Cell Mode . . . . . . . . . . . . . . . . . . . . . . . . . . 266

Relationship with QoS Downstream Rate Application . . . . . . . . . . . . . . . . . 267

Guidelines for Configuring the Cell Shaping Mode with QoS Parameters . . . . . . 267

Configuring a Parameter Definition to Shape Ethernet Traffic Using Cell

Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268

Example:QoS Parameter Configurationfor QoS CellMode andByte Adjustment

for Cell Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269

Complete Configuration Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

Chapter 29 Configuring Byte Adjustment for Shaping Rates with QoS Parameters . . 275

Byte Adjustment for ADSL and VDSL Traffic Overview . . . . . . . . . . . . . . . . . . . . 275

Byte Adjustment for Cell Shaping of ADSL Traffic Overview . . . . . . . . . . . . 275

Calculation and Example of Byte Adjustment for Cell Shaping . . . . . . . 276

Byte Adjustment for Frame Shaping of VDSL Traffic Overview . . . . . . . . . . 277

System Calculation for Byte Adjustment of ADSL and VDSL Traffic . . . . . . . 277

Guidelines for Configuring Byte Adjustment of Cell and Frame Shaping Rates

Using QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

Configuring a Parameter Definition to Adjust Cell Shaping Rates for ADSL

Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

Configuring a Parameter Definition to Adjust Frame Shaping Rates for VDSL

Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

Chapter 30 Configuring the Downstream Rate Using QoS Parameters . . . . . . . . . . . . 283

QoS Downstream Rate Application Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

Downstream Rate and the Shaping Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

QoS Adaptive Mode and Downstream Rate . . . . . . . . . . . . . . . . . . . . . . . . . 284

Obtaining Downstream Rates from a DSL Forum VSA . . . . . . . . . . . . . . . . . 284

Guidelines for Configuring QoS Downstream Rate . . . . . . . . . . . . . . . . . . . . . . . 285

Configuring a Parameter Definition for QoS Downstream Rate . . . . . . . . . . . . . . 285

Example: QoS Parameter Configuration for QoS Downstream Rate . . . . . . . . . . 287

Complete Configuration Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291

Part 7 Monitoring and Troubleshooting QoS

Chapter 31 Monitoring QoS on E Series Routers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

Monitoring Service Levels with Traffic Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . 296

Monitoring Service Levels with Traffic-Class Groups . . . . . . . . . . . . . . . . . . . . . . 297

Monitoring Queue Thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298

Monitoring Queue Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

Monitoring Drop Profiles for RED and WRED . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302

Monitoring the QoS Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303

Monitoring the Configuration of Scheduler Profiles . . . . . . . . . . . . . . . . . . . . . . . 309

Monitoring Shared Shapers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310

Monitoring Shared Shaper Algorithm Variables . . . . . . . . . . . . . . . . . . . . . . . . . . 312

Monitoring Forwarding and Drop Events on the Egress Queue . . . . . . . . . . . . . . . 313

Monitoring Forwarding and Drop Rates on the Egress Queue . . . . . . . . . . . . . . . 314

Monitoring Queue Statistics for the Fabric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318

Monitoring the Configuration of Statistics Profiles . . . . . . . . . . . . . . . . . . . . . . . . 319

Monitoring the QoS Profiles Attached to an Interface . . . . . . . . . . . . . . . . . . . . . 320

Monitoring the Configuration of QoS Port-Type Profiles . . . . . . . . . . . . . . . . . . . . 321

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Monitoring the Configuration of QoS Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

Monitoring the QoS Configuration of ATM Interfaces . . . . . . . . . . . . . . . . . . . . . . 324

Monitoring the QoS Configuration of IP Interfaces . . . . . . . . . . . . . . . . . . . . . . . . 326

Monitoring the QoS Configuration of Fast Ethernet, Gigabit Ethernet, and

10-Gigabit Ethernet Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328

Monitoring the QoS Configuration of IEEE 802.3ad Link Aggregation Group

Bundles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

Monitoring the Configuration of QoS Interface Sets . . . . . . . . . . . . . . . . . . . . . . 330

Monitoring the Configuration of QoS Interface Supersets . . . . . . . . . . . . . . . . . . 331

Monitoring the AAA Downstream Rate for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . 332

Monitoring QoS Parameter Instances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332

Monitoring QoS Parameter Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335

Chapter 32 Troubleshooting QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

Troubleshooting Memory and Processor Use for Egress Queue Rate Statistics

and Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

Part 8 Index

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

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Part 1 QoS on the E Series Router

Chapter 1 Quality of Service Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Figure 1: Traffic Flow Through an E Series Router . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Part 2 Classifying, Queuing, and Dropping Traffic

Chapter 4 Configuring Dropping Behavior with RED and WRED . . . . . . . . . . . . . . . . . . . 25

Figure 2: Packets Dropped as Queue Length Increases . . . . . . . . . . . . . . . . . . . . . 26

Figure 3: Color-Blind RED Drop Profile with Colorless Queue Profile . . . . . . . . . . . 29

Figure 4: Color-Blind RED Drop Profile with Color-Sensitive Queue Profile . . . . . 30

Figure 5: Different Treatment of Colored Packets . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 6: Defining Different Drop Behavior for Each Queue . . . . . . . . . . . . . . . . . . 33

Figure 7: WRED and Dynamic Queue Thresholding . . . . . . . . . . . . . . . . . . . . . . . . 35

Part 3 Scheduling and Shaping Traffic

Chapter 6 QoS Scheduler Hierarchy Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Figure 8: QoS Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Chapter 7 Configuring Rates and Weights in the Scheduler Hierarchy . . . . . . . . . . . . . . 51

Figure 9: Port Shaping on an Ethernet Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Figure 10: Hierarchical Assured Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Chapter 8 Configuring Strict-Priority Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Figure 11: Sample Strict-Priority Scheduling Hierarchy . . . . . . . . . . . . . . . . . . . . . . 58

Figure 12: True Strict-Priority Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Figure 13: Relative Strict-Priority Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Figure 14: Tuning Latency on Strict-Priority Queues . . . . . . . . . . . . . . . . . . . . . . . . 63

Figure 15: Sample Strict-Priority Scheduling Hierarchy . . . . . . . . . . . . . . . . . . . . . 64

Figure 16: Sample Relative Strict-Priority Scheduler Hierarchy . . . . . . . . . . . . . . . 66

Chapter 9 Shared Shaping Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Figure 17: Implicit Constituent Selection for Compound Shared Shaper: Mixed

Interface Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Chapter 10 Configuring Simple Shared Shaping of Traffic . . . . . . . . . . . . . . . . . . . . . . . . 75

Figure 18: Simple Shared Shaping over ATM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Figure 19: Simple Shared Shaping over Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Figure 20: VP Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Figure 21: Hierarchical Simple Shared Shaping over Ethernet . . . . . . . . . . . . . . . . 82

Chapter 11 Configuring Variables in the Simple Shared Shaping Algorithm . . . . . . . . . 85

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Figure 22: Simple Shared Shaper Behavior Without Algorithm Controls . . . . . . . 85

Figure 23: Less Conservative Simple Shared Shaper Behavior . . . . . . . . . . . . . . . 86

Figure 24: More Liberal Simple Shared Shaper Behavior . . . . . . . . . . . . . . . . . . . . 86

Figure 25: Dynamic Rate When Video Flow Starts . . . . . . . . . . . . . . . . . . . . . . . . . 92

Figure 26: Dynamic Rate When Video Flow Stops . . . . . . . . . . . . . . . . . . . . . . . . . 93

Chapter 12 Configuring Compound Shared Shaping of Traffic . . . . . . . . . . . . . . . . . . . . 95

Figure 27: VC Compound Shared Shaping Example . . . . . . . . . . . . . . . . . . . . . . . 98

Figure 28: VP Compound Shared Shaping Example . . . . . . . . . . . . . . . . . . . . . . 100

Chapter 13 Configuring Implicit and Explicit Constituent Selection for Shaping . . . . 103

Figure 29: Implicit Constituent Selection for Compound Shared Shaper at

Best-Effort Node . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

Figure 30: Implicit Constituent Selection for Compound Shared Shaper at

Best-Effort Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Figure 31: Weighted Shared Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Figure 32: Implicit Constituent Selection for Compound Shared Shaper: Mixed

Interface Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Figure 33: Explicit Constituent Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Figure 34: Case 1: Explicit Constituent Selection with Weighted Constituents . . . 113 Figure 35: Case 2: Explicit Constituent Selection with Weighted Constituents . . 114

Part 4 Creating a QoS Scheduler Hierarchy on an Interface with QoS

Profiles

Chapter 16 Configuring and Attaching QoS Profiles to an Interface . . . . . . . . . . . . . . . . 125

Figure 36: Munged Profile Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Figure 37: Attaching QoS Profiles to ATM Subinterfaces . . . . . . . . . . . . . . . . . . . . 133

Figure 38: Attaching QoS Profile to ATM Interface and Subinterface . . . . . . . . . . 135

Figure 39: Diffserv Configuration with Multiple Traffic-Class Groups . . . . . . . . . . 139

Figure 40: Diffserv Configuration Without Traffic-Class Groups . . . . . . . . . . . . . 140

Chapter 17 Configuring Shadow Nodes for Queue Management . . . . . . . . . . . . . . . . . . 141

Figure 41: Phantom Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

Figure 42: Shadow Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

Part 5 Interface Solutions for QoS

Chapter 19 Configuring an Integrated Scheduler to Provide QoS for ATM . . . . . . . . . . . 151

Figure 43: Integrated ATM Scheduler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

Figure 44: Default Integrated Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

Figure 45: Low-Latency Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Figure 46: Low-CDV Mode (per-VP CDVT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

Figure 47: Low-CDV Mode (per-VC CDVT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

Chapter 21 Configuring QoS for 802.3ad Link Aggregation Groups . . . . . . . . . . . . . . . . 175

Figure 48: 802.3ad Link Aggregation Scheduler Hierarchy . . . . . . . . . . . . . . . . . . 178

Figure 49: Subscriber LoadBalanced Scheduler Hierarchy for Port 0 . . . . . . . . . 180

Figure 50: Subscriber LoadBalanced Scheduler Hierarchy for Port 1 . . . . . . . . . . 180

Figure 51: Subscriber Allocation and Load Balancing . . . . . . . . . . . . . . . . . . . . . . . 181

Chapter 22 Configuring QoS for L2TP Sessions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

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Figure 52: LNS (Non-MLPPP) Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . . . . . 188

Figure 53: LNS (MLPPP) QoS Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . . . . . 188

Figure 54: LAC over Ethernet (Without VLANs) Scheduler Hierarchy . . . . . . . . . 188

Figure 55: LAC over Ethernet (With LANs) Scheduler Hierarchy . . . . . . . . . . . . . 189

Figure 56: LAC over ATM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

Chapter 23 Configuring Interface Sets for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Figure 57: VLAN Interface Column with Interface Sets . . . . . . . . . . . . . . . . . . . . . 198

Figure 58: Scheduler Hierarchy with Nodes at Interface Set and Superset . . . . . 198

Part 6 Managing Queuing and Scheduling with QoS Parameters

Chapter 24 QoS Parameter Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

Figure 59: Relationship of Parameter Definitions, Scheduler Profiles, and QoS

Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

Chapter 25 Configuring a QoS Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Figure 60: Physical Network Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

Figure 61: QoS Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

Chapter 26 Configuring Hierarchical QoS Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

Figure 62: Hierarchical Parameters Scheduler Hierarchy . . . . . . . . . . . . . . . . . . . 247

Chapter 27 Configuring IP Multicast Bandwidth Adjustment with QoS Parameters . . 253

Figure 63: Scheduler Hierarchy with QoS Adjustment for IP Multicast . . . . . . . . 257

Chapter 28 Configuring the Shaping Mode for Ethernet with QoS Parameters . . . . . 265

Figure 64: Byte Adjustment for VC1 and VC2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270

Chapter 29 Configuring Byte Adjustment for Shaping Rates with QoS Parameters . . 275

Figure 65: Byte Adjustment Calculation for Ethernet and ATM

Encapsulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

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List of Tables

About the Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxvii

Table 1: Notice Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxviii

Table 2: Text and Syntax Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxviii

Part 1 QoS on the E Series Router

Chapter 1 Quality of Service Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Table 3: QoS Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Table 4: QoS Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Part 2 Classifying, Queuing, and Dropping Traffic

Chapter 3 Configuring Queue Profiles for Buffer Management . . . . . . . . . . . . . . . . . . . . 17

Table 5: Egress Memory and Region Size on ASIC Line Modules . . . . . . . . . . . . . . 19

Part 3 Scheduling and Shaping Traffic

Chapter 9 Shared Shaping Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Table 6: Shared Shaper Terminology Used in This Chapter . . . . . . . . . . . . . . . . . . 68

Table 7: Comparison of Simple and Compound Shared Shaping . . . . . . . . . . . . . 69

Chapter 11 Configuring Variables in the Simple Shared Shaping Algorithm . . . . . . . . . 85

Table 8: Guidelines for Configuring Simple Shared Shaper Algorithm

Table 9: Rising Edge Sample When Video Flow Starts . . . . . . . . . . . . . . . . . . . . . . 91

Table 10: Data When Video Flow Stops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Chapter 13 Configuring Implicit and Explicit Constituent Selection for Shaping . . . . 103

Table 11: Comparison of Implicit and Explicit Shared Shaping . . . . . . . . . . . . . . . 104

Table 12: Bandwidth Allocation for Case 1 Explicit Constituents . . . . . . . . . . . . . . 113

Table 13: Bandwidth Allocation for Case 2 Explicit Constituents . . . . . . . . . . . . . . 114

Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Part 4 Creating a QoS Scheduler Hierarchy on an Interface with QoS

Profiles

Chapter 16 Configuring and Attaching QoS Profiles to an Interface . . . . . . . . . . . . . . . . 125

Table 14: Interface Types and Supported Commands . . . . . . . . . . . . . . . . . . . . . . 125

Chapter 17 Configuring Shadow Nodes for Queue Management . . . . . . . . . . . . . . . . . . 141

Table 15: Shadow Node Consumption of Node and Queue Resources . . . . . . . . 144

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JunosE 11.3.x Quality of Service Configuration Guide

Part 5 Interface Solutions for QoS

Chapter 19 Configuring an Integrated Scheduler to Provide QoS for ATM . . . . . . . . . . . 151

Table 16: qos-mode-port Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

Table 17: Operational Shaping Modes for ERX7xx Models, ERX14xx Models, and

the ERX310 Router . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

Table 18: Operational Shaping Modes for the E120 Router and E320 Router . . . 158

Chapter 20 Configuring QoS for Gigabit Ethernet Interfaces and VLAN

Subinterfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

Table 19: Operational Shaping Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

Chapter 21 Configuring QoS for 802.3ad Link Aggregation Groups . . . . . . . . . . . . . . . . 175

Table 20: Load Balancing Algorithm Parameters . . . . . . . . . . . . . . . . . . . . . . . . . 184

Chapter 23 Configuring Interface Sets for QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Table 21: Interface Set Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

Part 6 Managing Queuing and Scheduling with QoS Parameters

Chapter 24 QoS Parameter Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

Table 22: QoS Parameter Terminology Used in This Chapter . . . . . . . . . . . . . . . . 212

Chapter 25 Configuring a QoS Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Table 23: Attributes in Parameter Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Table 24: Sample Parameter Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

Table 25: Valid and Invalid Parameter Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

Table 26: Operators for Parameter Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . 222

Chapter 28 Configuring the Shaping Mode for Ethernet with QoS Parameters . . . . . 265

Table 27: Supported Interfaces for qos-shaping-mode and qos-cell-mode

Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266

Table 28: Byte Adjustment for Subscribers VC1 and VC2 . . . . . . . . . . . . . . . . . . . 270

Chapter 29 Configuring Byte Adjustment for Shaping Rates with QoS Parameters . . 275

Table 29: Header Lengths for Ethernet Encapsulation . . . . . . . . . . . . . . . . . . . . . 276

Table 30: Header Lengths for ATM Encapsulation . . . . . . . . . . . . . . . . . . . . . . . . 277

Table 31: Byte Adjustment Values for Frame and Cell Shaping Modes . . . . . . . . 277

Chapter 30 Configuring the Downstream Rate Using QoS Parameters . . . . . . . . . . . . 283

Table 32: Access Loop Types and Resultant Shaping Mode . . . . . . . . . . . . . . . . 284

Table 33: Shaping Rate and Shaping Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

Part 7 Monitoring and Troubleshooting QoS

Chapter 31 Monitoring QoS on E Series Routers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

Table 34: show traffic-class Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296

Table 35: show traffic-class-group Output Fields . . . . . . . . . . . . . . . . . . . . . . . . 297

Table 36: show qos queue-thresholds Output Fields . . . . . . . . . . . . . . . . . . . . . . 301

Table 37: show queue-profile Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302

Table 38: show drop-profile Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303

Table 39: show qos scheduler-hierarchy Output Fields . . . . . . . . . . . . . . . . . . . . 309

Table 40: show scheduler-profile Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . 310

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List of Tables

Table 41: show qos shared-shaper Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . 311

Table 42: show qos shared-shaper-control Output Fields . . . . . . . . . . . . . . . . . . 312

Table 43: show egress-queue events Output Fields . . . . . . . . . . . . . . . . . . . . . . . 313

Table 44: show egress-queue rates Output Fields . . . . . . . . . . . . . . . . . . . . . . . . 317

Table 45: show fabric-queue Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318

Table 46: show statistics-profile Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . 319

Table 47: show qos interface-hierarchy Output Fields . . . . . . . . . . . . . . . . . . . . . 320

Table 48: show qos-profile Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323

Table 49: show interfaces atm Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324

Table 50: show ip interface Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326

Table 51: show interfaces Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328

Table 52: show interfaces lag members Output Fields . . . . . . . . . . . . . . . . . . . . 330

Table 53: show qos-interface-set Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . 331

Table 54: show qos-interface-superset Output Fields . . . . . . . . . . . . . . . . . . . . . 332

Table 55: show aaa qos downstream-rate Output Fields . . . . . . . . . . . . . . . . . . 332

Table 56: show qos-parameter Output Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . 334

Table 57: show qos-parameter-define Output Fields . . . . . . . . . . . . . . . . . . . . . . 335

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JunosE 11.3.x Quality of Service Configuration Guide

Page 27

About the Documentation

•

E Series and JunosE Documentation and Release Notes on page xxvii

•

Audience on page xxvii

•

E Series and JunosE Text and Syntax Conventions on page xxvii

•

Obtaining Documentation on page xxix

•

Documentation Feedback on page xxix

•

Requesting Technical Support on page xxix

E Series and JunosE Documentation and Release Notes

For a list of related JunosE documentation, see

http://www.juniper.net/techpubs/software/index.html .

If the information in the latest release notes differs from the information in the documentation, follow the JunosE Release Notes.

To obtain the most current version of all Juniper Networks®technical documentation, see the product documentation page on the Juniper Networks website at

http://www.juniper.net/techpubs/.

Audience

This guide is intended for experienced system and network specialists working with Juniper Networks E SeriesBroadband Services Routers in an Internet access environment.

E Series and JunosE Text and Syntax Conventions

Table 1 on page xxviii defines notice icons used in this documentation.

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JunosE 11.3.x Quality of Service Configuration Guide

Table 1: Notice Icons

Table 2 on page xxviii defines text and syntax conventions that we use throughout the E Series and JunosE documentation.

DescriptionMeaningIcon

Indicates important features or instructions.Informational note

Indicates a situation that might result in loss of data or hardware damage.Caution

Alerts you to the risk of personal injury or death.Warning

Alerts you to the risk of personal injury from a laser.Laser warning

Table 2: Text and Syntax Conventions

Representscommandsand keywordsin text.Bold text like this

Fixed-width text like this

Italic text like this

Plus sign (+) linking key names

Syntax Conventions in the Command Reference Guide

Representsinformationas displayedon your terminal’s screen.

•

Emphasizes words.

•

Identifies variables.

•

Identifies chapter, appendix, and book names.

keys simultaneously.

ExamplesDescriptionConvention

•

Issue the clock source command.

•

Specify the keyword exp-msg.

host1(config)#traffic class low-loss1Represents text that the user must type.Bold text like this

host1#show ip ospf 2

Routing Process OSPF 2 with Router ID 5.5.0.250

Router is an Area Border Router (ABR)

•

There are two levels of access: user and privileged.

•

clusterId, ipAddress.

•

Appendix A, System Specifications

Press Ctrl + b.Indicates that you must press two or more

terminal lengthRepresents keywords.Plain text like this

mask, accessListNameRepresents variables.Italic text like this

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Table 2: Text and Syntax Conventions (continued)

About the Documentation

ExamplesDescriptionConvention

| (pipe symbol)

or variable to the left or to the right of this symbol. (The keyword or variable can be either optional or required.)

[ ]* (brackets and asterisk)

that can be entered more than once.

Represent required keywords or variables.{ } (braces)

Obtaining Documentation

To obtain the most current version of all Juniper Networks technical documentation, see the Technical Documentation page on the Juniper Networks Web site at

http://www.juniper.net/.

To download complete sets of technical documentation to create your own documentation CD-ROMs or DVD-ROMs, see the Portable Libraries page at

http://www.juniper.net/techpubs/resources/index.html

diagnostic | lineRepresents a choice to select one keyword

[ internal | external ]Represent optional keywords or variables.[ ] (brackets)

[ level1 | level2 | l1 ]*Represent optional keywords or variables

{ permit | deny } { in | out }

{ clusterId | ipAddress }

Copies of the Management Information Bases (MIBs) for a particular software release are available for download in the software image bundle from the Juniper Networks Web site athttp://www.juniper.net/.

Documentation Feedback

We encourage you to provide feedback, comments, and suggestions so that we can improve the documentation to better meet your needs. Send your comments to

techpubs-comments@juniper.net, or fill out the documentation feedback form at

https://www.juniper.net/cgi-bin/docbugreport/. If you are using e-mail, be sure to include

the following information with your comments:

•

Document or topic name

•

URL or page number

•

Software release version

Requesting Technical Support

Technical productsupport isavailable through theJuniper NetworksTechnical Assistance Center (JTAC). If you are a customer with an active J-Care or JNASC support contract,

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JunosE 11.3.x Quality of Service Configuration Guide

or are covered under warranty, and need post-sales technical support, you can access our tools and resources online or open a case with JTAC.

•

JTAC policies—For a complete understanding of our JTAC procedures and policies, review the JTAC User Guide located at

http://www.juniper.net/us/en/local/pdf/resource-guides/7100059-en.pdf .

•

Product warranties—For product warranty information, visit

http://www.juniper.net/support/warranty/ .

•

JTAC hours of operation—The JTAC centers have resources available 24 hours a day, 7 days a week, 365 days a year.

Self-Help Online Tools and Resources

For quick and easy problem resolution, Juniper Networks has designed an online self-service portal called the Customer Support Center (CSC) that provides you with the following features:

•

Find CSC offerings: http://www.juniper.net/customers/support/

•

Search for known bugs: http://www2.juniper.net/kb/

•

Find product documentation: http://www.juniper.net/techpubs/

•

Find solutions and answer questions using our Knowledge Base: http://kb.juniper.net/

•

Download the latest versions of software and review release notes:

http://www.juniper.net/customers/csc/software/

•

Search technical bulletins for relevant hardware and software notifications:

https://www.juniper.net/alerts/

•

Join and participate in the Juniper Networks Community Forum:

http://www.juniper.net/company/communities/

•

Open a case online in the CSC Case Management tool: http://www.juniper.net/cm/

To verifyservice entitlement by product serialnumber, use our Serial Number Entitlement (SNE) Tool: https://tools.juniper.net/SerialNumberEntitlementSearch/

Opening a Case with JTAC

You can open a case with JTAC on the Web or by telephone.

•

Use the Case Management tool in the CSC at http://www.juniper.net/cm/ .

•

Call 1-888-314-JTAC (1-888-314-5822 toll-free in the USA, Canada, and Mexico).

For international or direct-dial options in countries without toll-free numbers, see

http://www.juniper.net/support/requesting-support.html .

Page 31

PART 1

QoS on the E Series Router

•

Quality of Service Overview on page 3

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Page 33

CHAPTER 1

Quality of Service Overview

The quality of service (QoS) feature enables your E Series router to distinguish traffic with strict timing requirements from traffic that can tolerate delay, jitter, and loss.

QoS topics are discussed in the following sections:

•

QoS on the E Series Router Overview on page 3

•

QoS Audience on page 4

•

QoS Platform Considerations on page 4

•

QoS Terms on page 5

•

QoS Features on page 7

•

Configuring QoS on the E Series Router on page 9

•

QoS References on page 9

QoS on the E Series Router Overview

QoS is a suite of features that configure queuing and scheduling on the forwarding path of the Juniper Networks E Series Broadband Services Routers. QoS provides a level of predictability and control beyond the best-effort delivery that the router provides by default. Best-effort service provides packet transmission with no assurance of reliability, delay, jitter, or throughput.

QoS as developed for E Series routers conforms to the IETF Differentiated Services (DiffServ) model (RFCs 2597 and 2598). DiffServ networks classify packets into one of a smallnumber ofaggregated flowsor traffic classes for which youcan configure different QoS characteristics. The Juniper Networks QoS architecture extends DiffServ to support edge features such as high-density queuing.

The E Series router supports:

•

IETF architecture for differentiated services

•

Assured forwarding per-hop-behavior (PHB) groups

•

Expedited forwarding PHB groups

The router supports configurable queuing and scheduling. It has an application-specific integrated circuit (ASIC) scheduler that supports thousands of queues in a hierarchical

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E Series router

JunosE 11.3.x Quality of Service Configuration Guide

round-robin (HRR) scheduler. Thescheduler allows the routerto allocateseparate queues for each forwarding interface. Separate queues enable fair access to buffers and bandwidth for each subscriber connected to the router.

Allocating queues per interface allows an Internet service provider (ISP) to shape an individual subscriber’s traffic flows to specifiedrates independentof the underlyingLayer 2 network type.

For a list of related RFCs, see Configuring QoS on the E Series Router on page 9•

Documentation

QoS Audience

This topic collection contains configuration information for two types of QoS users: QoS administrators and QoS clients.

QoS administrators are responsible for implementing a QoS queuing architecture by defining drop profiles, queue profiles, scheduler profiles, QoS profiles, andQoS parameter definitions.

QoS clients are responsible for configuring services for individual subscribers by creating parameter instances. The parameter instances that QoS clients can create depend on the settings defined in parameter definitions by the QoS administrator.

Documentation

For information about QoS users and QoS parameters, see QoS Parameter Audience

•

on page 211

QoS Platform Considerations

QoS is supported on all E Series line modules except for the ES2 10G Uplink LM.

Figure 1 on page 4 shows the traffic flow through the router.

Figure 1: Traffic Flow Through an E Series Router

For information about the modules supported on E Series routers:

•

See the ERXModuleGuide for modulessupportedon ERX7xx models,ERX14xx models, and the Juniper Networks ERX310 Broadband Services Router.

•

See the E120 and E320 Module Guide for modules supported on the Juniper Networks E120 and E320 Broadband Services Routers.

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Interface Specifiers

Chapter 1: Quality of Service Overview

The majority of the configuration task examples in this topic collection use the slot/port format to specify an interface. However, the interface specifier format that you use depends on the router that you are using.

For ERX7xx models, ERX14xx models, and ERX310 routers, use the slot/port format. For example,the followingcommand specifies anATM interfaceon slot 0, port 1of an ERX7xx model, ERX14xx model, or ERX310 router.

host1(config)#interface gigabitEthernet 0/1

For E120 and E320 routers, use the slot/adapter/port format, which includes an identifier for the bay in which the I/O adapter (IOA) resides. In the software, adapter 0 identifies the right IOA bay (E120 router) and the upper IOA bay (E320 router); adapter 1 identifies the left IOA bay (E120 router) and the lower IOA bay (E320 router). For example, the following command specifies a10-Gigabit Ethernet interface on slot 5, adapter 0, port 0 of an E320 router.

host1(config)#interface tenGigabitEthernet 5/0/0

Documentation

QoS Terms

For moreinformationabout supported interface typesand specifiers onE Series routers,

•

see Interface Types and Specifiers.

Table 3 on page 5 defines terms used in this discussion of QoS.

Table 3: QoS Terminology

DescriptionTerm

Assured rate

Best effort

Best-effort queue

Best-effort scheduler node

Bandwidth guaranteeduntil thenode below in theschedulerhierarchy is oversubscribed.

Network forwards as many packets as possible in as reasonable a time aspossible. This is thedefaultper-hop behavior (PHB)for packet transmission.

For a logical interface, the queue associated with the best-effort traffic class for that logical interface,

The scheduler node associated with a logical interface and traffic class group pair, and where the traffic class group contains the best-effort traffic class. Also known as best-effort node.

CDV

CDVT

Cell delay variation. Measures the difference between a cell’s expected and actual transfer delay. Determines the amount of jitter.

Cell delay variation tolerance. Specifies the acceptable tolerance of CDV (jitter).

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JunosE 11.3.x Quality of Service Configuration Guide

Table 3: QoS Terminology (continued)

DescriptionTerm

Effective weight

Group node

HAR

HRR

Latency

Management Information Base (MIB)

Queue

The result of a weight or an assured rate. Users configure the scheduler node byspecifying eitheran assured rate or aweight within a scheduler profile. An assured rate, in bits per second, is translated into a weight. The resultant weight is referred to as an effective weight.

A scheduler node associated with a {port interface, traffic-class group} pair. Because the logical interface is the port, only one such scheduler node can exist for each traffic-class group above the port. This node aggregates all traffic for traffic classes in the group.

Hierarchical assured rate. Dynamically adjusts bandwidth for scheduler nodes.

Hierarchicalround-robin.Allocates bandwidth toqueues in proportion to their weights.

Delay in the transmission of a packet through a network from beginning to end.

Supported on the E Series router.Proprietary QoS

First-in-first-out (FIFO) set of buffers that control packets on the data path.

QoS port-type profile

Scheduler hierarchy

Scheduler node

Supplies theQoS information for forwarding interfacesstacked above ports of the associated interface type.

Applies the rules in the QoS profile to a specific interface.QoS profile attachment

Allows you to throttle a queue to a specified rate.Rate shaping

Random early detection congestion avoidance technique.RED

A hierarchical, tree-likearrangementof scheduler nodes andqueues. The router supports up to three levels of scheduler nodes stacked above a port. The port scheduler is at level 0, with two levels of scheduler nodes at levels 1 and 2. A final level of queues is stacked above the nodes.

An element within the hierarchical scheduler that implements bandwidth controls for agroupof queues.Queues are stacked above scheduler nodes in a hierarchy. The root node is associated with a channel or physical port.

Bandwidth in a queue or node can be throttled to a specified rate.Shaping rate

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Table 3: QoS Terminology (continued)

DescriptionTerm

Chapter 1: Quality of Service Overview

QoS Features

Shared shaper constituent

All nodes and queues that are associated with a logical interface that is being shared shapedare considered potential constituents of the shared shaper.

Specifies the relative weight for queues in the traffic class.Weight

Weighted random early detection congestion avoidance technique.WRED

Table 4 on page 7 describes the major QoS features supported on the E Series router.

Table 4: QoS Features

DescriptionFeature

Best effort

Differentiated services

Drop profile

Default traffic class for packets being forwarded across the device. Packets that are not assigned to a specific traffic class are assigned to the best-effort traffic class.

•

Assured forwarding—See RFC 2597.

•

Expedited forwarding—See RFC 2598.

Template that specifies active queue management in the form of WRED behavior of an egress queue.

Port shaping

QoS parameters

QoS port-type profile

QoS profile

Queue profile

Shapes the aggregate trafficthrough a port or channel to a rate that is less than the line or port rate.

Creates a queuing architecture withoutthe numericsubscriber rates and weights in scheduler profiles. You then use the same QoS and scheduler profiles across all subscribers who use the same services but at different bandwidths, reducing the total number of QoS profiles and scheduler profiles required.

QoS profile that is automatically attached to ports of the corresponding type if you do not explicitly attach a QoS profile.

Collection of QoS commands that specify queue profiles, drop profiles, scheduler profiles, and statistics profiles in combination with interface types.

Template that specifies the buffering and tail-dropping behavior of an egress queue.

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JunosE 11.3.x Quality of Service Configuration Guide

Table 4: QoS Features (continued)

DescriptionFeature

Rate shaping

Relative strict-priority scheduling

Scheduler profile

Shared rate shaping

Statistics profile

Strict-priority scheduling

Mechanism that throttlesthe rateat which aninterface can transmit packets.

Note: Rate shaping as presented in policy management in releases before JunosE Release 4.0 is deprecated and converted to QoS profiles and scheduler profiles.

Provides strict-priority scheduling within a shaped aggregate rate. For example, it lets you provide 1 Mbps of aggregate bandwidth to a subscriber, with up to 500 Kbps of the bandwidth for low-latency traffic. If there is no strict-priority traffic, the low-latency traffic can use up to the full aggregate rate of 1 Mbps.

Configures the bandwidth at which queues drain as a function of relative weight, assured rate, and shaping rate.

Mechanism for shaping a logical interface's aggregate traffic to a rate when the traffic for that logical interface is queued through more than one scheduler hierarchy.

Template that specifies rate statistics and event-gathering characteristics.

Designates the traffic class (queue) that receives top priority for transmission of its packets through a port. It is implemented with a special strict-priority scheduler node that is stacked directly above the port.

Traffic class

Traffic-class group

WRED

A chassis-wide grouping of queues and buffers that support transmission of a designated set of traffic across the chassis, from ingress line module, through the switch fabric, and onto the egress line module.

The router supports up to eight traffic classes, and therefore up to eight queues per logical interface.

Separate hierarchy of scheduler nodes and queues over a port. A traffic-class group uses one level of the scheduler hierarchy, level 1.

Trafficclassesbelong to thedefault groupunless they are specifically assigned to a named group. All queues are stacked in a single scheduler hierarchy above the physical port. When you configure a traffic class inside a group, its queues are stacked separately. The most common reason for creating separate scheduler hierarchies is to implement strict priority scheduling for all queues in the group.

The router supports up to four traffic-class groups. A traffic class cannot belong to more than one group.

Signals end-to-end protocols such as TCP that the router is becoming congested along a particular egress path. The intent is to trigger TCP congestion avoidance in a random set of TCP flows before congestion becomes severe and causes tail dropping on a large number of flows.

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Configuring QoS on the E Series Router

Several of the tasks for configuring QoS on your E Series router are optional.

To configure QoS on your E Series router:

1. Create and configure a traffic class.

See “Traffic Class and Traffic-Class Groups Overview” on page 13.

2. (Optional) Create one or more traffic-class groups.

See “Traffic Class and Traffic-Class Groups Overview” on page 13.

3. (Optional) To configure nondefault buffer management, create a queue profile.

See “Queuing and Buffer Management Overview” on page 17.

4. (Optional) To configure RED or WRED, create a drop profile.

See “Dropping Behavior Overview” on page 25.

Chapter 1: Quality of Service Overview

5. (Optional) To gather rate statistics, create a statistics profile.

See “QoS Statistics Overview” on page 37.

6. Configure a scheduler hierarchy with a scheduler profile.

See “Scheduler Hierarchy Overview” on page 45.

7. (Optional) Configure shaping:

•

Configure shaping and shared shaping using the scheduler profile.

See “RateShaping andPortShaping Overview” onpage51, “Simple Shared Shaping Overview” on page 75, and “Compound Shared Shaping Overview” on page 95.

•

Configure shaping rates independent of the QoS profile and scheduler profile using QoS parameters.

See “ParameterDefinition Attributes for QoSAdministratorsOverview” on page215.

8. Create a QoS profile. QoS profiles reference queue, drop, statistics, and scheduler

profiles.

See “Queuing and Buffer Management Overview” on page 17.

9. Attach the QoS profile to one or more interfaces, or specify the profile as a QoS

port-type profile for a given interface type.

See “Queuing and Buffer Management Overview” on page 17.

QoS References

For more information about QoS, see the following resources:

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JunosE 11.3.x Quality of Service Configuration Guide

•

RFC 2474—Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers (December 1998)

•

RFC 2475—An Architecture for Differentiated Services (December 1998)

•

RFC 2597—Assured Forwarding PHB Group (June 1999)

•

RFC 2598—An Expedited Forwarding PHB (June 1999)

•

RFC 2698—A Two Rate Three Color Marker (September 1999)

•

RFC 2990—Next Steps for the IP QoS Architecture (November 2000)

•

RFC 2998—A Framework for Integrated Services Operation over Diffserv Networks (November 2000)

•

RFC 3246—An Expedited Forwarding PHB (Per-Hop Behavior) (March 2002)

•

RFC 3260—New Terminology and Clarifications for Diffserv (April 2002)

•

DSL Forum Technical Report (TR)-059—DSL Evolution - Architecture Requirements for the Support of QoS-Enabled IP Services

•

Floyd, S., andJacobson, V. RandomEarlyDetectionfor Congestion Avoidance. IEEE/ACM Transactions on Networking 1(4), August 1993

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PART 2

Classifying, Queuing, and Dropping Traffic

•

Defining Service Levels with Traffic Classes and Traffic-Class Groups on page 13

•

Configuring Queue Profiles for Buffer Management on page 17

•

Configuring Dropping Behavior with RED and WRED on page 25

•

Gathering Statistics for Rates and Events in the Queue on page 37

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JunosE 11.3.x Quality of Service Configuration Guide

Page 43

CHAPTER 2

Defining Service Levels with Traffic Classes and Traffic-Class Groups

This chapter provides information for configuring traffic classes and traffic-class groups on the E Series router.

QoS topics are discussed in the following sections:

•

Traffic Class and Traffic-Class Groups Overview on page 13

•

Configuring Traffic Classes That Define Service Levels on page 14

•

Configuring Traffic-Class Groups That Define Service Levels on page 15

•

Monitoring Traffic Classes and Traffic-Class Groups for Defined Levels of Service on page 16

Traffic Class and Traffic-Class Groups Overview

A traffic class is a systemwide collection of buffers, queues, and bandwidth that you can allocate to provide a defined level of service to packets in the traffic class.

A traffic class corresponds to what the IETF DiffServ working group calls a traffic class in RFC 2597—Assured Forwarding PHB Group (June 1999).

Traffic classes are global to the router. Packets are:

•

Best-Effort Forwarding

The router has a default traffic class called best-effort. You cannot delete this class. You can add the best-effort class to a traffic-class group. The router assigns packets to the best-effort class in each of the following cases:

•

Classified into a traffic class on ingress or egress by input policies

Queued on fabric queues that are specific to the traffic class

Queued on the egress line module on queues that are specific to the traffic class

Scheduled for transmission by the scheduler

You do not create any other traffic classes.

Packets are not classified into a traffic class.

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•

Packets arrive at an egress line module that has no queues allocated for their traffic class.

Traffic-Class Groups Overview

You can put traffic classes into a group to create a hierarchy of scheduler nodes and queues. Organizing traffic into multiple traffic-class groups enables you to manage and shape traffic—by service class, for example—when the traffic classes are distributed across different VCs. A traffic-class group contains one or more traffic classes, but a particular traffic class can belong only to a single group—either the default group or one named group.

You can configure an auto-strict group and up to three extended traffic-class groups. You must puttraffic classes that require strict-priority scheduling inthe auto-strict group. You can optionally put traffic classes that need a separate round robin (for example, video) in an extended group.

A traffic class that is not contained in any named group is considered to belong to the default group. Traffic classes are placed in the default traffic-class group when the classes are configured—you can then move a class to another traffic-class group. When you delete a traffic-class from a named group, the class is automatically moved to the defaulttraffic-class group. ATM VC nodesthat are configured inthe default group (which is the factory default configuration) receive backpressure from the segmentation and reassembly (SAR) feature in the default qos-mode-port node.

Traffic-class groups are global in scope by default. However, you might want to manage certain traffic classes through particular line modules. If you have already created a traffic-class group, youcan subsequently specify a slot number to create alocal instance of thegroup that is restricted to the module occupying that slot. Characteristicsconfigured for the local group on the line module override those of the global group, for only that line module. Traffic classes in a globally scoped traffic-class group cannot belong to any other group. Traffic classes in alocaltraffic-class group cannot belong toany other group.

Documentation

Configuring Traffic Classes That Define Service Levels on page 14•

• Configuring Traffic-Class Groups That Define Service Levels on page 15

Configuring Traffic Classes That Define Service Levels

The router supports up to eight global traffic classes. Each traffic class can appear in only one traffic-class group. If not explicitly added to a traffic-class group, the traffic class is considered to be ungrouped.

To configure a traffic class:

1. Createa traffic class by assigninga name that represents the typeof serviceand enter

Traffic Class Configuration mode.

host1(config)#traffic-class low-loss1 host1(config-traffic-class)#

The traffic class name can be up to 31 characters. It cannot include spaces.

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Chapter 2: Defining Service Levels with Traffic Classes and Traffic-Class Groups

2. (Optional) Specify strict-priority scheduling across the fabric for queues in the traffic

class.

host1(config-traffic-class)#fabric-strict-priority

3. (Optional) For Juniper Networks ERX1440, E120 , and E320 Broadband Services

Routers, specify the relative weight for queues in the traffic class in the fabric.

host1(config-traffic-class)#fabric-weight 12

Fabric weight controls the bandwidth of fabric queues associated with the traffic class. It does not control theweight of egress queues associated with the traffic class. If multiple traffic classes are strict priority, the fabric weight determines which class gets more bandwidth.

The weight value is in the range 1–63. The default is 8. Zero is not a valid weight.

Documentation

Monitoring Traffic Classes and Traffic-Class Groups for Defined Levels of Service on

•

page 16

• fabric-strict-priority

• fabric-weight

• traffic-class

Configuring Traffic-Class Groups That Define Service Levels

You can configure atraffic-class group andenter Traffic Class Group Configurationmode, from which you can add classes to or delete classes from the group.

Each traffic class can appear in only one traffic-class group. If not explicitly added to a traffic-class group, the traffic class is considered to be ungrouped.

To configure a traffic-class group:

1. Create a traffic-class group by assigning a name that represents the type of service

and enter Traffic Class Group Configuration mode.

host1(config)#traffic-class-group assured slot 9 extended host1(config-traffic-class-group)#

The traffic class name can be up to 31 characters. It cannot include spaces.

If you do not specify a keyword, the group is strict-priority by default.

You can usethe auto-strict-priority keyword to explicitly configure asingle traffic-class group with strict-priority scheduling, regardless of the scheduler profile associated with the group node.

You can use the extended keyword to configure up to three extended traffic-class groups. Scheduling for these groups is determined bythe scheduler profile associated with thegroup node.If anexplicitlyconfigured strict-priority groupexists, the scheduler for the extended groups may not specify strict-priority scheduling.

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Use the slot slotNumber option to associate a pre-existing global traffic-class group with the module occupying that slot. Characteristics configured for the local group on the line module override those of the global group.

2. Add traffic classes to the traffic-class group.

host1(config-traffic-class-group)#traffic-class low-latency-traffic-class

Documentation

Configuring Traffic Classes That Define Service Levels on page 14•

• Monitoring Traffic Classes and Traffic-Class Groups for Defined Levels of Service on

page 16

• traffic-class

• traffic-class-group

Monitoring Traffic Classes and Traffic-Class Groups for Defined Levels of Service

To monitor traffic classes and traffic-class groups:

•

Monitoring Service Levels with Traffic Classes on page 296

•

Monitoring Service Levels with Traffic-Class Groups on page 297

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CHAPTER 3

Configuring Queue Profiles for Buffer Management

This chapter provides information for configuring queue profiles for buffer management on the E Series router.

QoS topics are discussed in the following sections:

•

Queuing and Buffer Management Overview on page 17

•

Memory Requirements for Queue and Buffers on page 19

•

Guidelines for Managing Queue Thresholds on page 19

•

Guidelines for Managing Buffers on page 20

•

Configuring Queue Profiles to Manage Buffers and Thresholds on page 22

•

Monitoring Queues and Buffers on page 24

Queuing and Buffer Management Overview

A queue is a set of first-in, first-out (FIFO) buffers that buffer packets on the data path. QoS associates queueswith atrafficclass/interface pair. For example,if you create4000 IP interfaces and configure each interface with four traffic classes, then 16,000 queues are created. For specific information about the maximum number of QoS queues supported, see JunosE Release Notes, Appendix A, System Maximums.

The E Series router dynamically manages the shared memory on egress line modules to provide a good balance between sharing the memory among queues and protecting an individual queue’s claim on its fair share of the egress memory.

When egress packet memory is in high demand and aggregate utilization of the packet memory is high, queue lengths are set to lengths that strictly partition egress memory into per-queue memory sections. This conservativebuffer-managementstrategy reserves a fair share of buffers for each queue, so that high bandwidth consumers cannot starve out moderate traffic consumers by allocating all the shared memory resource for themselves.

When egress packet memory is in low demand, amore liberal buffer management strategy is used to provide active queues with more access to the shared memory resource.

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The router dynamically varies queue lengths for all queues as the real-time demand on the egress packet memory changes. You can configure limits to prevent the router from setting queue lengths too low or too high.

Static Oversubscription

The router uses static oversubscription to vary queue thresholds based on the number of queues currently configured, which is relatively static. Static oversubscription is based on the assumption that,when a few queues are configured, many of thequeues arelikely to be active at the same time. When a large number of queues are configured, fewer queues are likely to be active at the same time.

When few queues are configured, buffer memory is strictly partitioned between queues to ensure that buffers are available for all queues. As the number of configured queues increases, buffer memory is increasingly oversubscribed to allow more buffer sharing. Reserving buffer space for all queues when many are expected to be idle is unnecessary and wasteful.

Dynamic Oversubscription

The router uses dynamicoversubscriptionto vary queuethresholdsbased on the amount of egress buffer memory in use. Therouterdivides egress buffer memory intoeight regions.

The size of the region depends on the ASIC type. For more information, see “Memory Requirements for Queue and Buffers” on page 19.

When buffer memory isin low demand, queuesare given large amounts of buffer memory. As the demand for buffer memory increases, queues are given progressively smaller amounts of buffer memory.

Color-Based Thresholding

Packets within the router are tagged with a drop precedence:

•

Committed—Green

•

Conformed—Yellow

•

Exceeded—Red

When the queue fills above the exceeded threshold, the router drops red packets, but still queues yellow and green packets. When the queue fills above the conformed drop threshold, the router queues only green packets.

NOTE: All color-based thresholds vary in proportion to the dynamic queue

length.

Documentation

Configuring Queue Profiles to Manage Buffers and Thresholds on page 22•

• Guidelines for Managing Queue Thresholds on page 19

• Guidelines for Managing Buffers on page 20

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• RED and WRED Overview on page 26

Memory Requirements for Queue and Buffers

JunosE Software uses 128-byte buffers.

The egress memory available for queues available depends on the ASIC and the line module. Table 5 on page 19 lists the egress memory.

Table 5: Egress Memory and Region Size on ASIC Line Modules

Chapter 3: Configuring Queue Profiles for Buffer Management

Documentation

To identify the type of ASIC used by a line module, see the ERX Module Guide and the

•

E120 and E320 Module Guide

• Guidelines for Managing Queue Thresholds on page 19

• Guidelines for Managing Buffers on page 20

Guidelines for Managing Queue Thresholds

To prevent the router from setting queue thresholds too low or too high, you can specify minimum and maximum queue thresholds. You can also specify the conformed length and exceeded length as percentages of the committed length.

Egress Memory (MB)Line ModuleASIC

Region Size (MB)

432All EFA line modulesEFA

864GE-2 and GE-HDEFFA

16128OC48

16128ES2 4G LM

1296ES2 10G LMTFA

Guidelines for Configuring a Maximum Threshold

We recommend that you constrain queue thresholds using committed or conformed threshold settings; any unused memory is redistributed to queues whose thresholds are not constrained. This use of thresholds is analogous to the way that shaping rates constrain bandwidth and cause bandwidth redistribution to unconstrained queues.

For example, voice queues are scheduled at strict priority; therefore, they require very little buffering. Configuring a maximum queue threshold enables the system to allocate more buffers to other queues in the system. Video queues are similar but because they are higher bandwidth, they might require higher maximum committed thresholds.

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You might want to limit latency of your multicast traffic by bounding the queue length using a maximum committed threshold. The following example configures the multicast queues so that the committed threshold never exceeds 20 KB, even when the egress memory is lightly loaded. The forfeited buffers are allocated to other queues.

host1(config)#queue-profile multicast host1(config-queue)#committed-length 0 20000 host1(config-queue)#exit

Be sure to include 0 in the syntax, or you will configure a minimum threshold.

Guidelines for Configuring a Minimum Threshold

Configuring a minimum threshold does not guarantee that a queue always obtains the minimum buffer allocation. You can configure 1000 queues with a minimum of 1 MB each, but the buffer memory is 32 MB or 128 MB, not 1 GB. In this case, the system moves into higher operating regions (global utilization) if all these queues buffer traffic, until it reaches 90 percent utilization. At that point, the thresholds must reduce to the reserved percentages, and the queue thresholds drop from a high threshold to a very low one. Queues arenot guaranteed to obtain any buffering, and are buffered in the orderin which they are received.

You can configure a minimum committed threshold by specifying a value such as 1000 with the committed-length command:

host1(config)#queue-profile multicast host1(config-queue)#committed-length 1000 20000 host1(config-queue)#exit

Documentation

Memory Requirements for Queue and Buffers on page 19•

• Configuring Queue Profiles to Manage Buffers and Thresholds on page 22

Guidelines for Managing Buffers

Queue profiles enable you to manage queue thresholds and buffers to manage the following common problems:

•

Queues that back up and consume too many buffers

•

Queues that cannot obtain buffers when they need them (called buffer starvation)

You can set the buffer weight to ensure that some sets of queues get higher thresholds than others. Buffer weight is analogous to weight in a scheduler profile. It directs the router to set the queue thresholds proportionately.

This feature provides graceful buffer allocation as the global utilization goes higher; queues with more buffer weight always obtain more buffers, but they do not undergo a dramatic drop in threshold when the system moves from region to region.

JunosE Software uses 128-byte buffers. When setting very small queue thresholds, keep the following guidelines in mind:

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Chapter 3: Configuring Queue Profiles for Buffer Management

•

Specifying a maximum queue length of 0 bytes disables queuing of packets on the queue.

•

Specifying a maximum queue length of 1–128 bytes creates a single 128-byte buffer for the queue.

•

Specifying a maximum queue length of 129–256 bytes creates two 128-byte buffers for the queue.

•

Packets and cells consume at least one buffer.

For example, a 64-byte packet consumes a single 128-byte buffer. If you specify a maximum queue lengthof 256 bytes, theneither two packetsof 64–128 bytesin length or a single packet of 129–256 bytes can be queued.

For example, suppose a line module with 4000 IP interfaces is configured with four queues per IP interface, corresponding to four traffic classes. Suppose that queues in two of the traffic classes are configured with a buffer weight of 24 to increase burst tolerance. The following example configures the video queue:

host1(config)#queue-profile video host1(config-queue)#buffer-weight 24 host1(config-queue)#exit host1(config)#

When the egress memory is fully loaded, dynamic oversubscription is 0 percent, and the 8000 queues with the default buffer weight strictly partition 25 percent of the 32-MB memory, leaving 75 percent of the memory for the queues weighted 24 (corresponding to the ratio 75 percent:25 percent, or 24:8). Therefore, these queues have committed thresholds of 1 KB each, and queues with the buffer weight of 24 have committed thresholds of 3 KB each. As the egress memory becomes progressively less loaded, all the queue thresholds increase proportionally, based on dynamic oversubscription, but the queues with buffer weight 24 are always set with thresholds three times larger than the default thresholds.

Guidelines for Managing Buffer Starvation

Buffer starvation most commonly occurs when queues or nodes exist in a large round robin, usually in thedefaulttraffic-class group. When the round robincongests,the queues back up and require more buffers. The traffic in the round robin starts to burst based on a single node or queue. After a packet is dequeued, the node or queue can wait for thousands of other queues to dequeue a packet before it can dequeue again. During this time, the queue backs up.

If you configure different scheduler profile weights or assured rates for nodes in a large and congestedround robin, the buffer starvation becomes apparent. Theproblemoccurs when the heavy weighted nodes wait theirturn in the round robin and thousands of other nodes dequeue. While the heavily weightednodes wait, the system needs tobuffer them. However, all queues receive the same buffer allocation by default. If the system goes to higher buffer regions, it starts dropping packets for all queues. When the heavy weight node finally transmits, it dequeues all buffers, but it cannot dequeue the packets that were dropped. You do not achieve the expected bandwidth based on scheduler profile weights.

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To manage buffer starvation, configure buffer weights on queues so they are in the same ratioas theexpected bandwidthfor the queues.For example, if twoqueues have scheduler weight (or assured-rate) in the ratio of 2:1, then set the buffer weights to the same ratio.

To manage buffer starvation, set the maximum-committed-threshold on queues that do not need buffering, and increase the buffer-weight for the heavily weighted queues in the round robin.

The system calculates the correct ratio for you. Issue the show egress queue rates command to see the ratio:

host1# show egress-queue rates brief interface fastEthernet 9/0.2 traffic forwarded aggregate minimum maximum interface class rate drop rate rate rate

---------------------- ----------------------- --------- --------- ------- ------ip FastEthernet9/0.2 best-effort 0 0 25000 1000000 videoTrafficClass 0 0 375000 1000000 multicastTrafficClass 0 0 925000 1000000 internetTrafficClass 0 0 50000 1000000 Total: 0 0

Queues reported: 4 Queues filtered (under threshold): 0 Queues disabled (no rate period): 0 Queues disabled (no resources): 0 Total queues: 4

The minimum rate for each queue is the approximate rate the queue achieves if all configured queues in the line module run infinite traffic. Configure the buffer weights in proportion to the minimum rate displayed by the system.

Documentation

Memory Requirements for Queue and Buffers on page 19•

• Configuring Queue Profiles to Manage Buffers and Thresholds on page 22

• Monitoring Forwarding and Drop Rates on the Egress Queue on page 314

Configuring Queue Profiles to Manage Buffers and Thresholds

A queue profile controls the buffering and dropping behavior of a set of egress queues by enabling you to set the buffer weight of the queue, the drop thresholds, and the constraints on queue lengths.

Set the queue lengths as follows:

•

To oversubscribe buffer memory, set a minimum queue length.

NOTE: If the sum of the queue minimum lengths is greater than the amount

of egress buffer memory, then the egress buffer memory is oversubscribed.

•

To configure a minimal level of buffering or to limit the buffering in queues, set a maximum queue length. For example, if you want to control latency by configuring

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Chapter 3: Configuring Queue Profiles for Buffer Management

very small queues, set the maximum queue length to 256 bytes. The system queues no more than 256 bytes.

If you do not set the queue lengths, the router varies the queue length dynamically in the range 1 KB–7 MB.

1. Create a queue profile and enter Queue Configuration mode.

host1(config)#queue-profile video host1(config-queue)# You can configure 16 queue profiles on an E Series router.

2. (Optional) Set the buffer weight of the queue.

host1(config-queue)#buffer-weight 16 Queues with a buffer weight of 16 are twice as long as queues with a buffer weight of

8. The range is 1–63; the default is 8.

3. (Optional) Set a minimum or maximum queue length for committed packets.

host1(config-queue)#committed-length 11000 15000 The range of minimum and maximum lengths is 0–1 GB. By default, there is no minimum

or maximum length. The color for committed packets is green.

Documentation

4. (Optional) Set a minimum or maximum queue length for conformed packets.

host1(config-queue)#conformed-length 10000 14000 The range of minimum and maximum lengths is 0–1 GB. By default, there is no minimum

or maximum length. The color for conformed packets is yellow.

5. (Optional) Set a minimum or maximum queue length for exceeded packets.

host1(config-queue)#exceeded-length 9000 10000 The range of minimum and maximum lengths is 0–1 GB. By default, there is no minimum

or maximum length. The color for exceeded packets is red.

6. (Optional) Set the conformed drop threshold as a percentage of the committed

threshold.

host1(config-queue)#conformed-fraction 60

The range is 0–100 percent; the default is 50.

7. (Optional) Set the exceeded drop threshold as a percentage of the committed

threshold.

host1(config-queue)#exceeded-fraction 40

The range is 0–100 percent; the default is 25.

Queuing and Buffer Management Overview on page 17•

• Guidelines for Managing Queue Thresholds on page 19

• Guidelines for Managing Buffers on page 20

• Memory Requirements for Queue and Buffers on page 19

• buffer-weight

• committed-length

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JunosE 11.3.x Quality of Service Configuration Guide

• conformed-fraction

• conformed-length

• exceeded-fraction

• exceeded-length

• queue-profile

Monitoring Queues and Buffers

To monitor queues and buffers, see:

•

Monitoring Queue Thresholds on page 298

•

Monitoring Queue Profiles on page 301

Page 55

CHAPTER 4

Configuring Dropping Behavior with RED and WRED

This chapter provides information for configuring dropping behavior using RED and WRED on the E Series router.

QoS topics are discussed in the following sections:

•

Dropping Behavior Overview on page 25

•

RED and WRED Overview on page 26

•

Configuring RED on page 27

•

Example: Configuring Average Queue Length for RED on page 28

•

Example: Configuring Dropping Thresholds for RED on page 28

•

Example: Configuring Color-Blind RED on page 29

•

Configuring WRED on page 30

•

Example: Configuring Different Treatment of Colored Packets for WRED on page 32

•

Example: Defining Different Drop Behavior for Each Traffic Class for WRED on page 32

•

Example: Configuring WRED and Dynamic Queue Thresholds on page 33

•

Monitoring RED and WRED on page 35

Dropping Behavior Overview

Drop profiles control the dropping behavior of a set of egress queues. They define the range within the queue where random early detection (RED) operates, the maximum percentage of packets to drop, and sensitivity to bursts of packets. Weighted random early detection (WRED) is an extension to RED that enables you to assign different RED drop profiles to each color of traffic.

The purpose of RED and WRED is to signal end-to-end protocols, such as TCP, that the router is becoming congested along a particular egress path. The intent is to trigger TCP congestion avoidance in a random set of TCP flows before congestion becomes severe and causes tail dropping on a large number of flows. Tail dropping can lead to TCP slow-starts,and taildropping on a large number of flows results inglobal synchronization.

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JunosE 11.3.x Quality of Service Configuration Guide

By default, tail dropping occurs when the length of a queue exceeds a threshold. Drop profiles allow you to employ active queue management by specifying RED and WRED parameters to be applied to an egress queue.

Congestion of an egress queue occurs when the rate of traffic destined for the queue exceeds the rate of traffic draining from the queue; the queue fills to its limit, and any further traffic destined to it must be discarded until there is room in the queue. RED and WRED monitor average queue length over time to detect incipient congestion.

You can combine drop profiles and queue profiles within a queue rule of a QoS profile to specify up to 256 unique queuing behaviors within the router. You can then associate these queuing behaviors in any combination with any of the egress queues.

Queuing and Buffer Management Overview on page 17•

Documentation

RED and WRED Overview

The scheduler maintains an average queue length for each queue configured for RED. When a packet is enqueued, the current queue length is weighted into the averagequeue length based on the average-length exponent in the drop profile.

•

Small exponent values weight the current queue length heavily, so the average queue length is more responsive to transient bursts.

•

Large exponent values weight the current queue length lightly, so the average queue length is less responsive to bursts.

When the average queue length exceeds the minimum threshold, RED begins randomly dropping packets. While the average queue length increases toward the maximum threshold, RED drops packets with increasing frequency, up to the maximum drop probability. When the average queue length exceeds the maximum drop threshold, all packets are dropped. Figure 2 on page 26 shows this behavior.

Figure 2: Packets Dropped as Queue Length Increases

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Chapter 4: Configuring Dropping Behavior with RED and WRED

WRED is an extension of RED that allows you to assign different RED drop thresholds to each color of traffic. The router assigns a color to each packet. Committed means green, conformed means yellow, and exceeded means red. When the queue fills above the exceeded threshold, the router drops red packets, but still queues yellow and green packets. When the queue fills above the conformed drop threshold, the router queues only green packets.

Documentation

Configuring RED

Configuring RED on page 27•

• Configuring WRED on page 30

Each line module supports a default drop profile and 15 configurable drop profiles. You can configure the default drop profile on all E Series line modules except for the ES2 10G LM.

To configure RED:

1. Create a drop profile and enter Drop Profile Configuration mode.

host1(config)#drop-profile internetDropProfile host1(config-drop-profile)#

You can configure up to 16 drop profiles.

2. Set the average-length exponent, which specifies the exponent used to weight the

average queue length over time, controlling WRED responsiveness.

host1(config-drop-profile)#average-length-exponent 9

•

Specifying an average-length exponent enables the RED average queue length computation.

•

A higher value smooths out the average and slows WRED reaction to congestion and decongestion,accommodatingshort bursts without dropping.Too large a value can smooth the average to the point that WRED does not react at all.

•

A lower value speeds up WRED reaction. Too low a value can cause overreaction to short bursts, dropping packets unnecessarily.

3. (Optional) Set the minimum and maximum threshold for committed traffic.

host1(config-drop-profile)#committed-threshold percent 30 90 4

4. (Optional) Set the minimum and maximum threshold for conformed traffic.

host1(config-drop-profile)#conformed-threshold percent 25 90 5

5. (Optional) Set the minimum and maximum threshold for exceeded traffic.

host1(config-drop-profile)#exceeded-threshold percent 20 90 6

The thresholds specify a linear relationship between average queue length and drop probability.

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JunosE 11.3.x Quality of Service Configuration Guide

You can express thresholds as eitherpercentages of maximum queue size by including the keyword percent, or as absolute byte values by omitting the keyword.

Documentation

Configuring WRED on page 30•

• Monitoring RED and WRED on page 35

• average-length-exponent

• committed-threshold

• conformed-threshold

• drop-profile

• exceeded-threshold

Example: Configuring Average Queue Length for RED

To enable calculation of average queue length, create a drop profile with a nonzero average-length exponent, reference the drop profile within a QoS profile, and attach the QoS profile to an interface.

The following drop profile enables the average queue length calculation, but does not initiate RED dropping behavior:

host1(config)#drop-profile averageOnly host1(config-drop-profile)#average-length-exponent 10

Documentation

Configuring RED on page 27•

• Dropping Behavior Overview on page 25

• RED and WRED Overview on page 26

Example: Configuring Dropping Thresholds for RED

You can specify different dropping behavior for committed (green), conformed (yellow), and exceeded (red) packets by specifying a minimum queuethreshold, maximum queue threshold, and maximum drop probability for each color of traffic.

By default, conformed threshold and exceeded threshold take the same values as the committed threshold. Therefore, if you specify only a committed threshold, conformed and exceededtrafficis treated like committed traffic. Similarly, if youspecify aconformed threshold without an exceeded threshold, exceeded traffic is treated like committed traffic.

The following drop profiles result in identical behavior:

host1(config)#drop-profile colorblind1 host1(config-drop-profile)#committed-threshold percent 30 90 5 host1(config-drop-profile)#exit host1(config)#drop-profile colorblind2 host1(config-drop-profile)#committed-threshold percent 30 90 5

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Chapter 4: Configuring Dropping Behavior with RED and WRED

host1(config-drop-profile)#conformed-threshold percent 30 90 5 host1(config-drop-profile)#exit host1(config)#drop-profile colorblind3 host1(config-drop-profile)#committed-threshold percent 30 90 5 host1(config-drop-profile)#conformed-threshold percent 30 90 5 host1(config-drop-profile)#exceeded-threshold percent 30 90 5

Documentation

Configuring RED on page 27•

• Dropping Behavior Overview on page 25

• RED and WRED Overview on page 26

Example: Configuring Color-Blind RED

You can configure RED so that packets are dropped without regard to color. To do so, you combine a drop profile that has a committed threshold configured with a queue profile that specifies the same queue length for committed, conformed, and exceeded packets, as shown in Figure 3 on page 29.

Figure 3: Color-Blind RED Drop Profile with Colorless Queue Profile

In the following example, the drop profile and queue profile combine to specify the following:

•

When the average queue length is between 30 percent full (30 KB) and 90 percent full (90 KB), up to 5 percent of the packets are randomly dropped regardless of their color.

•

When the average queue length is greater than 90 percent, all packets are dropped regardless of color.

host1(config)#drop-profile nocolor host1(config-drop-profile)#c ommitted-threshold percent 30 90 5 host1(config-drop-profile)#exit host1(config)#queue-profile colorless host1(config-queue)#committed-length 100000 100000 host1(config-queue)#conformed-fraction 100 host1(config-queue)#exceeded-fraction 100

To achieve the same drop treatment for each color, you can specify color-blind RED in combination with a color-sensitive queue profile, as shown in Figure 4 on page 30.

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Figure 4: Color-Blind RED Drop Profile with Color-Sensitive Queue Profile

In the following example, the drop profile and queue profile combine to specify the following:

•

When the average queue length is between 30 percent full (30 KB) and 90 percent full (90 KB), up to 5 percent of the packets are dropped randomly. In this case, the maximum queue length is 100 KB for green packets, 50 KB for yellow packets, and 25 KB for red packets. Therefore, the router randomly drops:

•

Red packets when the average queue length is between 7.5 KB and 22.5 KB

•

Yellow packets when the average queue length is between 15 KB and 45 KB

•

Green packets when the average queue length is between 30 KB and 90 KB

Documentation

Configuring WRED

•

When the average queue length is greater than 90 percent of the maximum queue length, all packets are dropped. Therefore, the router drops:

•

Red packets when the average queue length is greater than 22.5 KB

•

Yellow packets when the average queue length is greater than 45 KB

•

Green packets when the average queue length is greater than 90 KB

host1(config)#drop-profile colorblindRed host1(config-drop-profile)#committed-threshold percent 30 90 5 host1(config-drop-profile)#exit host1(config)#queue-profile colorSensitive host1(config-queue)#committed-length 100000 100000

Configuring RED on page 27•

• Dropping Behavior Overview on page 25

• RED and WRED Overview on page 26

The main difference between RED and WRED is that WRED deals with different colored packets. The router assigns a color to each packet. Committed means green, conformed means yellow, and exceeded means red.

Each line module supports a default drop profile and 15 configurable drop profiles.

WRED isnot supported onthe ES2 10GUplink LM. On the ES210G LM, youmust configure WRED in one of the 15 configurable drop profiles; you cannot configure its default drop profile.

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To enable support for 32,000 subscribers with 128,000 QoS queues on ES2 10G ADV LMs, scheduler memory enhancements have reduced the number of QoS rate counters that are supported per egress queue rom 7 to 5:

•

1 is used for forwarding events

•

3 are used for tail dropping behavior

•

1 is used for WRED functionality (an aggregate of all colors)

Each line module supports a default drop profile and 15 configurable drop profiles. On the ES210G ADV LM, youmust configure WRED inone ofthe 15configurable drop profiles; you cannot configure itsdefaultdrop profile. Queue rate statistics measure the forwarding and drop rates of each queue in bits per second. Queue event statistics configure the E Series router to count the number of times that forwarding or drop rates exceed a specific threshold. To display information about the number of committed packets and bytes dropped by WRED for ES2 10G ADV LMs, see the number displayed in the Dropped by WREDcommittedfield inthe output of the show ip interface command. The Dropped by WRED confirmed and Dropped by WRED exceeded fields always display a value of zero because of the single counter being used for WRED functionality being calculated and displayed in the Dropped by WRED committed field of the output.

To configure WRED:

1. Create a drop profile and enter Drop Profile Configuration mode.

host1(config)#drop-profile internetDropProfile host1(config-drop-profile)#

You can configure up to 16 drop profiles.

2. Set the average-length exponent, which specifies the exponent used to weight the

average queue length over time, controlling WRED responsiveness.

host1(config-drop-profile)#average-length-exponent 9

•

Specifying an average-length exponent enables the RED average queue length computation.

•

A lower value speeds up WRED reaction. Too low a value can cause overreaction to short bursts, dropping packets unnecessarily.

3. (Optional) Set the minimum and maximum threshold for committed traffic.

host1(config-drop-profile)#committed-threshold percent 30 90 4

4. (Optional) Set the minimum and maximum threshold for conformed traffic.

host1(config-drop-profile)#conformed-threshold percent 25 90 5

5. (Optional) Set the minimum and maximum threshold for exceeded traffic.

host1(config-drop-profile)#exceeded-threshold percent 20 90 6

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The thresholds specify a linear relationship between average queue length and drop probability.

You can express thresholds as eitherpercentages of maximum queue size by including the keyword percent, or as absolute byte values by omitting the keyword.

Documentation

Configuring RED on page 27•

• Monitoring RED and WRED on page 35

• average-length-exponent

• committed-threshold

• conformed-threshold

• drop-profile

• exceeded-threshold

Example: Configuring Different Treatment of Colored Packets for WRED

Figure 5 on page 32 shows a WRED drop profile that yields progressively more aggressive drop treatment for each color. Exceeded traffic is dropped over a wider range and with greater maximum drop probability than conformed or committed traffic. Conformed traffic is dropped over a wider range and with greater maximum drop probability than committed traffic.

The commands to configure this example are:

host1(config)#drop-profile wredColored host1(config-drop-profile)#committed-threshold percent 30 90 3 host1(config-drop-profile)#conformed-threshold percent 25 90 5 host1(config-drop-profile)#exceeded-threshold percent 20 90 10

Figure 5: Different Treatment of Colored Packets

Documentation

Configuring WRED on page 30•

• Dropping Behavior Overview on page 25

• RED and WRED Overview on page 26

Example: Defining Different Drop Behavior for Each Traffic Class for WRED

You can define different dropping behaviors for each traffic class in the router. By doing so, you can assign less aggressive drop profiles to higher-priority queues and more aggressive drop profiles to lower-priority queues. Figure 6 on page 33 shows an example

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Chapter 4: Configuring Dropping Behavior with RED and WRED

that classifies packets into one of four traffic classes. Each traffic class has a different queueing behavior, drop treatment, and scheduler treatment.

Figure 6: Defining Different Drop Behavior for Each Queue

Documentation

Configuring WRED on page 30•

• Dropping Behavior Overview on page 25

• RED and WRED Overview on page 26

Example: Configuring WRED and Dynamic Queue Thresholds

RED typically operates on fixed-size queues, and you can configure the router to use fixed-size queues. However, by default, the router employs dynamic queue thresholds to provide a good balance between sharing the egress buffer memory between queues and protecting an individual queue’s claim on its fair share of the egress memory. Fixed-size queues become problematic as the number of configured queues scales into the thousands, because allocating disjointed partitions of buffer memory to each queue means the allocations become quite small, and most likely not all queues are simultaneously active.

In general, you use queues as follows:

•

Fixed-size queues on core routers and core-facing interfaces where the number of queues is relatively small (tens or hundreds, but not thousands).

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•

Dynamic queues on edge-facing interfaces where the number of queues is relatively large (thousands).

As shown in Figure 7 on page 35, queue lengths extend to oversubscribe memory when aggregate memory utilization is low, and contract to strictly partition memory when memory utilization is high. Dynamic thresholding enforces fairness when free buffers are scarce and promotes sharing when buffers are plentiful. Dynamic queue thresholds are discussed in “Queuing andBuffer Management Overview” on page 17. Figure7 onpage 35 illustrates WRED behavior with dynamic queue thresholding.

To configure WRED to run on queues whose limits dynamically expand and contract, use the percent keyword when you configure thresholds in a drop profile. For example:

host1(config)#drop-profile internetDropProfile host1(config-drop-profile)#average-length-exponent 9 host1(config-drop-profile)#committed-threshold percent 30 90 4 host1(config-drop-profile)#conformed-threshold percent 25 90 5 host1(config-drop-profile)#exceeded-threshold percent 20 90 6

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Figure 7: WRED and Dynamic Queue Thresholding

Chapter 4: Configuring Dropping Behavior with RED and WRED

Documentation

Configuring WRED on page 30•

• Dropping Behavior Overview on page 25

• RED and WRED Overview on page 26

Monitoring RED and WRED

To monitor drop profiles, see:

•

Monitoring Drop Profiles for RED and WRED on page 302

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CHAPTER 5

Gathering Statistics for Rates and Events in the Queue

This chapter provides information for configuringstatistics profiles on the E Seriesrouter.

QoS topics are discussed in the following sections:

•

QoS Statistics Overview on page 37

•

Configuring Statistic Profiles for QoS on page 39

•

Configuring Rate Statistics on page 39

•

Configuring Event Statistics on page 40

•

Clearing QoS Statistics on the Egress Queue on page 41

•

Clearing QoS Statistics on the Fabric Queue on page 42

•

Monitoring QoS Statistics for Rates and Events on page 42

QoS Statistics Overview

Statistics profiles enable you to gather statistics for the rate at which packets are forwarded out of a queue and for the rate at which committed, conformed, or exceeded packets are dropped. Statistics profiles also enable you to use events to monitor the rate statistics.You can thenuse show commands to view theresultsof thestatistics gathering.

You can create up to 250 statistics profiles on the E Series Broadband Services Routers. The profiles are referenced by a queue rule within a QoS profile.

Statistics cannot be collected on failover queues.

When you create a statistics profile, you specify the time period over which statistics are gathered. To gather event statistics, you configure the thresholdsfor triggering rate-event reporting.

•

Rate period—Time period, in seconds, over which statistics are gathered. For example, a 30-second rate period results in rate statistics being gathered over 30-second time segments.

•

Forwarding rate threshold—Threshold for forwarding rate events. A forwarding-rate event is counted whenever the forwarding rate exceeds the specified threshold.

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•

Committed drop threshold—Threshold above which committed drop rate events are counted.

•

Conformed drop threshold—Threshold above which conformed drop rate events are counted.

•

Exceeded drop threshold—Threshold above which exceeded drop rate events are counted.

Rate Statistics

You can configure the E Series router to gather statistics for the rate at which queues forward and drop packets.

Queue rate statistics measure the forwarding and drop rates of each queue in bits per second. All bytes in the Layer 2 encapsulation are included in the rate calculation. For example, rates for a queue on Ethernet include the Ethernet and VLAN encapsulations.

For ATM modules, you can optionally configure queue statistics and queue rates to include the cell encapsulation and padding. Cell encapsulation and padding are referred to as the cell tax. The QoS shaping mode that you set on ATM line modules determines whether queue rate statistics include cell tax.

•

If the interface is configured with frame-based QoS shaping mode, the egress queue measures frame rate statistics; an ATM cell tax is not included.

•

If the interface is configured with cell-based QoS shaping mode, the egress queue measures cell rate statistics; cell rates include ATM Adaptation Layer 5 (AAL5) encapsulation and cell padding.

•

If the interface is configured with byte adjustment, the egress queue measures rate statistics that are adjusted to the byte adjustment value.

NOTE: If you change the QoS shaping mode value in the middle of a rate

period, the gathered rates are a mixture of cell- and frame-based rates for that one rate period. The next rate period uses a rate based on the new QoS shaping mode setting.

Event Statistics

You can configure the E Series router to count the number of times that forwarding or drop rates exceed a specific threshold. Events can be useful when you are monitoring service level agreements. For example, you might count the number of times that the drop rate of a queue is nonzero.

Bulk Statistics Support for QoS Statistics

You can obtain queue-level QoS statistics for each logical interface by queryingthe SNMP MIB. However, using SNMP to obtain queue-level statisticsconsumes significant network bandwidth because SNMP polls large volumes of data frequently. As an alternative to using the SNMP MIB, you can use the bulkstats statistics application.

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The bulk statistics application provides components to configure and organize network accountingdata in a flexiblemanner.The application reducesthe consumption ofnetwork bandwidth by collecting queue-level statistics and periodically transferring the data to a remote server. You can configure the bulk statistics schemas to export network accounting data. In particular, the QoS schema supports the export of queue-level QoS statistics on egress queues for various interface types.

Configuring QoS schemas helps service providers monitor their network and report congestion and oversubscription by obtaining queue-level statistics and configuration information for each logical interface.

For information about schemas and configuring a bulk statistics schema to export queue-level QoS statistics for egress queues on the router, see JunosE System Basics Configuration Guide, Chapter 4, Configuring SNMP.

Configuring Statistic Profiles for QoS

To begin to configure a statistics profile, enter Statistics Profile Configuration mode.

Chapter 5: Gathering Statistics for Rates and Events in the Queue

•

Issue the statistics-profile command from Global Configuration mode:

host1(config)#statistics-profile statpro-1 host1(config-statistics-profile)#

The router supports up to 250 statistics profiles.

Documentation

Configuring Rate Statistics on page 39•

• Configuring Event Statistics on page 40

• Monitoring QoS Statistics for Rates and Events on page 42

• statistics-profile

Configuring Rate Statistics

To gather rate statistics:

1. Create the statistics profile.

host1(config)#statistics-profile statpro-5

2. Set the length of time during which statistics are counted.

host1(config-statistics-profile)#rate-period 45 Rate period range is 1–43200 seconds.

3. Reference the statistics profile by a QoS profile.

host1(config)#qos-profile qospro-3 host1(config-qos-profile)#ip queue traffic-class tc1 scheduler-profile sp1

4. Attach the QoS profile to the appropriate interface.

host1(config)#interface gigabitEthernet 1/0 host1(config-subif)#qos-profile qospro-3

statistics-profile statpro-5

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host1(config-subif)#exit

5. (Optional) Display the rate statistics.

host1#show egress-queue rates interface gigabitEthernet 1/0

Documentation

Configuring Statistic Profiles for QoS on page 39•

• Configuring a QoS Profile on page 126

• Monitoring QoS Statistics for Rates and Events on page 42

• interface

• qos-profile

• queue

• rate-period

• statistics-profile

Configuring Event Statistics

To configure the router to count events on a queue, you configure the threshold above which forwarding or drop events are counted.

A forwarding rate event occurs each time the forwarding rate exceeds the threshold during the specified rate period.

A drop event occurs each time the number of packets dropped exceeds the threshold during the specified rate period.

To gather event statistics:

1. Create the statistics profile.

host1(config)#statistics-profile statpro-1

2. Set the length of time during which statistics are counted.

host1(config-statistics-profile)#rate-period 30 Rate period range is 1–43200 seconds.

3. (Optional) Set the threshold above which forwarding rate events are counted.

host1(config-statistics-profile)#forwarding-rate-threshold 10000000 Forwarding rate threshold range is 0–1073741824 bps; default is no threshold.

4. (Optional) Set a threshold for committed (green) packets.

host1(config-statistics-profile)#committed-drop-threshold 2000000 Drop rate threshold range is 0–1073741824 bps; default is no threshold.

5. (Optional) Set a threshold for conformed (yellow) packets.

host1(config-statistics-profile)#conformed-drop-threshold 4000000 Drop rate threshold range is 0–1073741824 bps; default is no threshold.

6. (Optional) Set a threshold for exceeded (red) packets.

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host1(config-statistics-profile)#exceeded-drop-threshold 6000000 Drop rate threshold range is 0–1073741824 bps; default is no threshold.

7. Reference the statistics profile in a QoS profile.

host1(config)#qos-profile qospro-1 host1(config-qos-profile)#ip queue traffic-class tc1 scheduler-profile sp1

statistics-profile statpro-1

8. Attach the QoS profile to the appropriate interface.

host1(config)#interface gigabitEthernet 1/0 host1(config-subif)#qos-profile qospro-1 host1(config-subif)#exit

9. (Optional) Display the event statistics.

host1#show egress-queue events interface gigabitEthernet 1/0

Documentation

Configuring Statistic Profiles for QoS on page 39•

• Configuring a QoS Profile on page 126

• Monitoring QoS Statistics for Rates and Events on page 42

• committed-drop-threshold

• conformed-drop-threshold

• exceeded-drop-threshold

• forwarding-rate-threshold

• qos-profile

• queue

• rate-period

• statistics-profile

Clearing QoS Statistics on the Egress Queue

To clear statistics from the egress queue for the specified interface and traffic class:

•

Issue the clear egress-queue command.

host1#clear egress-queue atm 3/0 explicit traffic-class class15

Use theexplicit keywordto clear queues onlyon the specifiedinterfaceand not queues stacked above the interface.

Documentation

Monitoring QoS Statistics for Rates and Events on page 42•

• clear egress-queue

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Clearing QoS Statistics on the Fabric Queue

To clear statistics from the fabric queue for the specified traffic class and egress slot:

•

Issue the clear fabric-queue command.

host1#clear fabric-queue traffic-class class15 egress-slot 3

By default, statistics for all traffic classes and all slots are cleared.

Documentation

Monitoring QoS Statistics for Rates and Events on page 42•

• clear fabric-queue

Monitoring QoS Statistics for Rates and Events

To monitor statistics for rates and events in the queue:

•

Monitoring Forwarding and Drop Events on the Egress Queue on page 313

•

Monitoring Forwarding and Drop Rates on the Egress Queue on page 314

•

Monitoring Queue Statistics for the Fabric on page 318

•

Monitoring the Configuration of Statistics Profiles on page 319

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PART 3

Scheduling and Shaping Traffic

•

QoS Scheduler Hierarchy Overview on page 45

•

Configuring Rates and Weights in the Scheduler Hierarchy on page 51

•

Configuring Strict-Priority Scheduling on page 57

•

Shared Shaping Overview on page 67

•

Configuring Simple Shared Shaping of Traffic on page 75

•

Configuring Variables in the Simple Shared Shaping Algorithm on page 85

•

Configuring Compound Shared Shaping of Traffic on page 95

•

Configuring Implicit and Explicit Constituent Selection for Shaping on page 103

•

Monitoring a QoS Scheduler Hierarchy on page 117

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Page 75

CHAPTER 6

QoS Scheduler Hierarchy Overview

This chapter provides information for configuring the QoS scheduler hierarchy using scheduler profiles on the E Series router.

QoS topics are discussed in the following sections:

•

Scheduler Hierarchy Overview on page 45

•

Configuring a Scheduler Hierarchy on page 47

•

Configuring a Scheduler Profile for a Scheduler Node or Queue on page 48

•

Using Expressions for Bandwidth and Burst Values in a Scheduler Profile on page 48

Scheduler Hierarchy Overview

The egress line module scheduler is an HRR scheduler. Figure 8 on page 46 is an example of a QoS scheduler’s hierarchy.

As shown in Figure 8 on page 46, the queues feeding a physical port are organized in a hierarchy. At each level in the hierarchy, the scheduler uses shaping rates, hierarchical or assured rates, and relative weights to determine the allocated bandwidth:

•

The scheduler selects a first-level node based on the allocated bandwidth.

•

The scheduler then selects a second-level node from the group of nodes that are stackedabove the selected first-levelnode. This selection isalso based on the allocated bandwidth.

•

Finally, the scheduler selects a queue from the group of queues stacked above the second-level node.

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Figure 8: QoS Scheduler Hierarchy

Shaping Rates, Assured Rates, and Relative Weights in a Scheduler Hierarchy

The scheduler supportshierarchicaland static assured rates,relative weights, andshaping rates on all three levels of the hierarchy: first-level node, second-level node, and queue. The bandwidth delivered from a given node or queue is a function of the shaping rate and either the assured rate or relative weight:

•

When thescheduleris notcongested, the shapingratesdetermine which node or queue can claim the bandwidth. The shaping rate specifies the maximum bandwidth to the node or queue.

•

When the scheduler is congested, either the hierarchical or static assured rate or the weight specifies the minimum bandwidth.

•

If the scheduler is configured to use a static assured rate and the assured rate is other than none (the default), it is used to determine the allocated bandwidth, and the weight setting is ignored. If the assured rate is zero, the weight setting is used to determine the bandwidth.

The static assured rate specifies the desired bandwidth. This rate is guaranteed until the bandwidth becomes oversubscribed.

•

If the scheduler is configured to use hierarchical assured rate, the scheduler dynamically adjusts the amount of allocated bandwidth for service delivery based on the sum of the assured rates of all child nodes and queues.

•

The assured rate also specifies that if bandwidth is over- or undersubscribed, all adjustments are made in proportion to the original assured-rate specification.

For example, if Node A is configured to receive 40 Mbps and Node B receives 20 Mbps, any available bandwidth above the subscribed total of 60 Mbps would be allocated to the two nodes at the same 2-to-1 ratio. Similarly, if the bandwidth were oversubscribedand only 30 Mbpswere available, thisamount would also be allocated to thetwo nodes atthe 2-to-1ratio, with Node A getting 20 Mbps andNode B getting 10 Mbps.

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NOTE: For E Series ASIC modules, strict priority is supported only for a

single first-level scheduler node.

When determining the shaping rate, the system includes all bytes in Layer 2 encapsulations. The packets that are included in the rate depend on the Layer 2 node that is specified in the QoS profile. For example, the shaping rate for an Ethernet node includes bytes from the Ethernet and VLAN encapsulations.

Documentation

Static and Hierarchical Assured Rate Overview on page 53•

• Rate Shaping and Port Shaping Overview on page 51

• Shared Shaping Overview on page 67

• Configuring a Scheduler Hierarchy on page 47

Configuring a Scheduler Hierarchy

When you configure a scheduler hierarchy, you configure the scheduler profile and assign attributes.

To configure a scheduler hierarchy:

1. Configure a scheduler profile.

See “Configuring a Scheduler Profile for a Scheduler Node or Queue” on page 48.

2. (Optional) Configure attributes in the scheduler profile.

•

Configure a shaping rate for rate shaping or port shaping.

See “Configuring Rate Shaping for a Scheduler Node or Queue” on page 52 or “Configuring Port Shaping” on page 52.

•

Configure an assured rate.

See “Configuring an Assured Rate for a Scheduler Node or Queue” on page 54.

•

Configure the HRR weight.

See “Configuring the HRR Weight for a Scheduler Node or Queue” on page 56.

•

Configure shared shaping.

See “Configuring Simple Shared Shaping” on page 77 and “Configuring Compound Shared Shaping” on page 96.

•

Configure implicit and explicit constituent selection.

See “Configuring Implicit Constituents for Simple or Compound Shared Shaping” on page 110 and “Configuring Explicit Constituents for Simple or Compound Shared Shaping” on page 115.

3. Reference the scheduler profile in a QoS profile and apply to an interface.

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See “Configuring a QoS Profile” on page 126 and “Attaching a QoS Profile to an Interface” on page 128.

Documentation

Scheduler Hierarchy Overview on page 45•

• For information about configuring a scheduling hierarchy with QoS parameters, see

Parameter Definition Attributes for QoS Administrators Overview on page 215

Configuring a Scheduler Profile for a Scheduler Node or Queue

To create a scheduler profile for a scheduler hierarchy:

•

Create a scheduler profile by assigning a name that represents the type of service and enter Scheduler Profile Configuration mode.

host1(config)#scheduler-profile sp-1mbs host1(config-scheduler-profile)#

The router supports up to 1000 scheduler profiles.

Documentation

Configuring Rate Shaping for a Scheduler Node or Queue on page 52•

• Configuring Port Shaping on page 52

• Configuring an Assured Rate for a Scheduler Node or Queue on page 54

• Configuring the HRR Weight for a Scheduler Node or Queue on page 56

• Configuring Simple Shared Shaping on page 77

• Configuring Compound Shared Shaping on page 96

Using Expressions for Bandwidth and Burst Values in a Scheduler Profile

Expressions are combinations of constants andoperators. You can specify somescheduler profile attributes using an expression, such as the shaping rate. All operations within expressions are performed using64 bit unsigned math,resultingis a 32 bit, signed integer value.

Expressions consist of both operators and operand values. Operators are mathematical functions, and operand values are the inputs for the mathematical function. Operand values can be an integer. You specify an expression consisting of an operand, followed by zero or more [ operator, operand ] pairs.

You can specify bandwidth as a percentage and burst in milliseconds or bytes by using expressions with the shaping-rate, shared-shaping-rate, assured-rate, and weight commands.

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When calculating constant shaping rates, use the following formula to translate burst values from bytes to milliseconds (ms):

Using this formula, a 2 Mbps service with a 500 KB burst yields:

The shaping rate is calculated when the QoS profile is attached based on the parameter instance. For example:

host1(config)# scheduler-profile sp-1mbs (config-scheduler-profile)# shaping-ratevideo-bandwidth % 100 burst 500 milliseconds

Documentation

When the shaping rate for video-bandwidth is 2 Mbps, theburst value is calculated using the following formula:

The burst value in bits is calculated as:

The burst value in bytes is calculated as:

• For more information about using expressions within scheduler profiles that are used

for QoS parameters, see Scheduler Profiles and Parameter Expressions for QoS Administrators on page 221

• Configuring Rate Shaping for a Scheduler Node or Queue on page 52

• Configuring Port Shaping on page 52

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• Configuring an Assured Rate for a Scheduler Node or Queue on page 54

• Configuring the HRR Weight for a Scheduler Node or Queue on page 56

• Configuring Simple Shared Shaping on page 77

• Configuring Compound Shared Shaping on page 96

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CHAPTER 7

Configuring Rates and Weights in the Scheduler Hierarchy

This chapter provides information for configuring shapingrates, assured rates, andweights in the QoS scheduler hierarchy using scheduler profiles.

QoS topics are discussed in the following sections:

•

Rate Shaping and Port Shaping Overview on page 51

•

Configuring Rate Shaping for a Scheduler Node or Queue on page 52

•

Configuring Port Shaping on page 52

•

Static and Hierarchical Assured Rate Overview on page 53

•

Configuring an Assured Rate for a Scheduler Node or Queue on page 54

•

Configuring the HRR Weight for a Scheduler Node or Queue on page 56

Rate Shaping and Port Shaping Overview

Rate shaping throttles the rate at which queues transmit packets. Rate shaping is TCP friendly; that is, it buffers packets that are above the rate, rather than dropping them.

Port shaping enables you to shape the aggregate traffic through a port or channel to a rate that is less than the line or port rate. With port shaping, you can configure scheduler nodes at the port level, as shown in Figure 9 on page 51.

Figure 9: Port Shaping on an Ethernet Module

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The per-port shaping feature provides the ability to shape the output of a port.

Documentation

Configuring Rate Shaping for a Scheduler Node or Queue on page 52•

• Configuring Port Shaping on page 52

Configuring Rate Shaping for a Scheduler Node or Queue

The router supports 64,000 rate shapers per line module. Shaping rates are multiples of 1 Kbps.

To configure a shaping rate for a scheduler node or queue:

1. Create a scheduler profile.

host1(config)#scheduler-profile video host1(config-scheduler-profile)#

2. Specify a shaping rate in the scheduler profile.

host1(config-scheduler-profile)#shaping-rate 128000 burst 32767 milliseconds host1(config-scheduler-profile)#shaping-rate 5000 x 90

The range for the shared-shaping rate is 1000–1000000000 bps (1Kbps–1000Kbps); the default is the minimum shaping rate (1 Kbps). The router rounds the rate to the next higher 8 Kbps.

Use the operator and operandValue variables to configure a shaping rate with an expression.

You can use the bps or kbps keywords to specify the unit of the shaping rate. By default, the shaping rate is configured in bps.

Use the burst keyword to specify the catch-up number associated with the shaper; the range is0–522240. Specifying 0 enables therouter to select an applicable default value.

Use the milliseconds or bytes keywords to specify the unit of the burst size.

Documentation

Rate Shaping and Port Shaping Overview on page 51•

• Configuring a Scheduler Profile for a Scheduler Node or Queue on page 48

• scheduler-profile

• shaping-rate

Configuring Port Shaping

To configure port-shaping:

1. Configure the scheduler profile and the shaping rate.

host1(config)#scheduler-profile 80mbps host1(config-scheduler-profile)#shaping-rate 80000000 host1(config-scheduler-profile)#exit

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Chapter 7: Configuring Rates and Weights in the Scheduler Hierarchy

2. Configure a QoS profile, specify the node command, and reference the

scheduler-profile.

host1(config)#qos-profile 80mbps host1(config-qos-profile)#ethernet node scheduler-profile 80mbps host1(config-qos-profile)#exit

3. Attach the QoS profile to the port.

host1(config)#interface fastethernet 2/0 host1(config-if)#qos-profile 80mbps

The sample configurationshapes Fast Ethernet port2/0 to a rate no higherthan 80Mbps.

Using the following configuration, you can shape the corresponding HDLC channel down to 20 Mbps:

host1(config)#scheduler-profile 20mbps host1(config-scheduler-profile)#shaping-rate 20000000 host1(config-scheduler-profile)#exit host1(config)#qos-profile 20mbps host1(config-qos-profile)#serial node scheduler-profile 20mbps host1(config-qos-profile)#exit host1(config)#interface serial 2/0:1/1 host1(config-if)#qos-profile 20mbps

Documentation

Rate Shaping and Port Shaping Overview on page 51•

• Configuring a Scheduler Profile for a Scheduler Node or Queue on page 48

• For more information about specifying an expression that you can reference within a

scheduler profile, see Using Expressions for Bandwidth andBurst Values ina Scheduler Profile on page 48

• node

• qos-profile

• scheduler-profile

• shaping-rate

Static and Hierarchical Assured Rate Overview

You can configure the effective weight of the scheduler node or queue by configuring a static assured rate or a hierarchical assured rate (HAR). The JunosE hierarchical assured rate(HAR) feature provides amore powerful andefficient method ofconfiguring assured rates than static assured rates.

When you use static assured rates, a queue is guaranteed to receive its assured rate only when its parent node is configured with an assured rate that equals the sum of all its child assured rates. Therefore, to ensure that a queue receives its specified assured rate, you must frequently recalculate the assured rates on all parent nodes in the queue’s hierarchy. This recalculation is necessary because of the number of scheduler nodes and queues that may be dynamically created or deleted through applications such as

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bandwidth-on-demand. Eventually, this complicated manual recalculation process becomes unreasonable and virtually impossible.

HAR replaces the manual recalculation process by directing the router to dynamically calculate the assured rate for a scheduler node based on the sum of the assured rates of allits child nodesand queues. Forexample,you mightuse HARto increase the effective weight of an ATM-VC scheduler node when a video queue is created, and to later restore the effective rate of the node when the video queue is deleted.

HAR is applicable only to level 1 and level 2 scheduler nodes, and is not applicable to queues or ports. When you configure HAR, the changes take place immediately. When you disable HAR, the scheduler node’s previous weight is restored.

Figure 10 on page 54 shows an application of HAR for VC nodes. In the example, VCs, which are configured for HAR, are stacked over virtual path (VP) nodes. The VP nodes are in turn stacked over an OC-3 ATM port. Each VC has a best-effort data queue, which currently has an assured rate of 20 Kbps. The VCs share equal portions of their parent VP's bandwidth. However, when the video queue is added to VC2, HAR enables VC2's share of the VP bandwidth to increase in proportion to the 1-Mbps video queue that was created. The bandwidth of sibling VC nodes, which have only a data queue, is decreased in equal proportions.

Figure 10: Hierarchical Assured Rate

Documentation

Configuring an Assured Rate for a Scheduler Node or Queue on page 54•

• Configuring the HRR Weight for a Scheduler Node or Queue on page 56

Configuring an Assured Rate for a Scheduler Node or Queue

You can configure the effective weight of the scheduler node or queue by configuring a static assured rate or a hierarchical assured rate (HAR). HAR dynamically adjusts the available bandwidth for a scheduler node based on the creation and deletion of other scheduler nodes.

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By default, the HRR weight is configured for the scheduler profile. If the assured rate setting is other than none (the default), then the assured rate is used instead of the HRR weight setting for the scheduler node or queue.

Tasks to configure an assured rate are:

•

Configuring a Static Assured Rate on page 55

•

Configuring a Hierarchical Assured Rate on page 55

•

Changing the Assured Rate to an HRR Weight on page 55

Configuring a Static Assured Rate

To configure a static assured rate:

1. Create a scheduler profile.

host1(config)#scheduler-profile static host1(config-scheduler-profile)#

2. Specify a numeric rate with the assured-rate command in the scheduler profile.

Chapter 7: Configuring Rates and Weights in the Scheduler Hierarchy

host1(config-scheduler-profile)#assured-rate 56000 host1(config-scheduler-profile)#assured-rate 50000 - 31000

For a static assured rate, specify the bits per second value in the range 25000–1000000000 bps (25 Kbps to 1 Gbps); the default is none (no assured rate).

Use the operator and operandValue variables to configure an assured rate with an expression.

Configuring a Hierarchical Assured Rate

To specify that theHAR isused for scheduler nodes (HAR is notused for queues orports):

1. Create a scheduler profile.

host1(config)#scheduler-profile har host1(config-scheduler-profile)#

2. Specify the hierarchical keyword with the assured-rate command in the scheduler

profile.

host1(config-scheduler-profile)#assured-rate hierarchical

Changing the Assured Rate to an HRR Weight

To change an assured rate to an HRR weight:

1. Create a scheduler profile.

host1(config)#scheduler-profile static host1(config-scheduler-profile)#

2. Delete the configured assured rate.

host1(config-scheduler-profile)#no assured-rate

The assured ratein the scheduler profile reverts to using the HRRweight specification.

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Documentation

Static and Hierarchical Assured Rate Overview on page 53•

• Configuring a Scheduler Profile for a Scheduler Node or Queue on page 48

• Configuring the HRR Weight for a Scheduler Node or Queue on page 56

• For more information about specifying an expression that you can reference within a

scheduler profile, see Using Expressions for Bandwidth andBurst Values ina Scheduler Profile on page 48

• assured-rate

• scheduler-profile

Configuring the HRR Weight for a Scheduler Node or Queue

By default, the HRR weight is configured for the scheduler profile. You can set a specific HRR weight of the scheduler node or queue. The weight value is used when no assured rate is set.

To configure a static weight:

1. Create a scheduler profile.

host1(config)#scheduler-profile relative host1(config-scheduler-profile)#

Documentation

2. Specify the weight value.

host1(config-scheduler-profile)#weight 10 host1(config-scheduler-profile)#weight 800 - 200

The weight value is in the range 0–4080. The default weight is 8. Weight 0 (zero) is a special weight that is used for relative strict-priority scheduling.

Use theoperatorand operandValue variables to configure a weightwith anexpression.

• Static and Hierarchical Assured Rate Overview on page 53

• For more information about specifying an expression that you can reference within a

scheduler profile, see Using Expressions for Bandwidth andBurst Values ina Scheduler Profile on page 48

• Relative Strict-Priority Scheduling Overview on page 58

• scheduler-profile

• weight

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CHAPTER 8

Configuring Strict-Priority Scheduling

This chapter provides information for configuring strict-priority scheduling.

QoS topics are discussed in the following sections:

•

Strict-Priority and Relative Strict-Priority Scheduling Overview on page 57

•

Comparison of True Strict Priority with Relative Strict Priority Scheduling on page 59

•

Configuring Strict-Priority Scheduling on page 63

•

Configuring Relative Strict-PriorityScheduling for AggregateShaping Rates on page 65

Strict-Priority and Relative Strict-Priority Scheduling Overview

You can configure one or more strict-priorityqueues perinterface. Strict-priority scheduling is implemented with a special strict-priority scheduler node that isstackeddirectlyabove the port.Queues stacked on topof thestrict-priority scheduler nodealways get bandwidth before other queues.

You can configure only one node at the first scheduler level as strict priority. If any node or queueabove the strict-prioritynode haspackets,it isscheduled next. Ifmultiplequeues above the strict-prioritynode have packets,the HRR algorithm selects which strict-priority queue is scheduled next.

Figure 11 on page 58 illustrates an example of a QoS scheduler’s hierarchy.

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Figure 11: Sample Strict-Priority Scheduling Hierarchy

One strictpriority traffic-class groupis called the auto-strict-priority group. The scheduler nodes and queues in the auto-strict-priority group receive strict-priority scheduling. If multiple queues above the strict-priority node have packets, the HRR algorithm selects which strict-priority queue is scheduled next.

NOTE: If you configured traffic shaping through traffic shape profiles in JunosE

releases before Release 4.0, traffic shaping is replaced with the rate-shaping feature, which is configured when you configure a scheduler profile.

Relative Strict-Priority Scheduling Overview

Relative strict-priority scheduling provides strict-priority scheduling within a shaped aggregate rate. For example, it allows you to provide 1 Mbps of aggregate bandwidth to a subscriber, with up to 500 Kbps of the bandwidth for low-latency traffic. If there is no strict-priority traffic, the low-latency traffic can use up to the full aggregate rate of 1 Mbps.

Relative strict prioritydiffers from true strict priorityin thatit can implement theaggregate shaping rate for both strict and nonstrict traffic. With true strict priority, you can shape the nonstrict or the strict traffic separately, but you cannot shape the aggregate to a single rate.

The best application of relative strict priority is on Ethernet, where you can shape the aggregate for each VLAN to a specified rate, and provision a strict and nonstrict queue for each VLAN above the shaped VLAN node.

To use relative strict priority, you configure strict-priority queues above the VC or VLAN scheduler node, thereby providing for strict-priority scheduling of the queues within the VC or VLAN. You configure relative strict priority without using QoS traffic-class groups, which causes strict-priority queues to appear in the same scheduler hierarchy as the nonstrict queues.

Relative strictpriority provides low latency only if you undersubscribe the port by shaping all VCs on the port so that the sum of the shaping rates is less than the port rate. The

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port will not become congested, and the latency caused by the round-robin behavior of both the HRR and cell schedulers is nominal. In these undersubscribed conditions, the latency of a strict-priority queue within each VC is calculated as if the VC were draining onto a wire with bandwidth equal to the shaped rate.

Relative strict priority is carried out in the HRR scheduler on E Series ASIC line modules.

Documentation

Comparison of True Strict Priority with Relative Strict Priority Scheduling on page 59•

• Configuring Strict-Priority Scheduling on page 63

• Configuring Relative Strict-Priority Schedulingfor AggregateShaping Rates on page 65

Comparison of True Strict Priority with Relative Strict Priority Scheduling

This section explains how the HRR and SAR schedulers handle true strict-priority and relative strict-priority configurations.

Schedulers and True Strict Priority

In the strict-priority configuration in Figure 12 on page 59, the queues stacked above the single strict priority scheduler node make up a round-robin separate from the nonstrict queues. All strict queues are drained to completion first, and any residual bandwidth is allocated to the nonstrict round-robin.

Figure 12: True Strict-Priority Configuration

This configuration provides low latency for the strict-priority queues, irrespective of the state of the nonstrict queues. The worst-case latency for a strict packet caused by a

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nonstrict packet is the propagation delay of a single large packet at the port rate. For a 1500 byte frame at OC3 rate, that latency is less than 100 microseconds.

Because the strict and nonstrictpackets for a VC are scheduled in separate round robins, the scheduler cannot enforce an aggregate rate for both of them.

Schedulers and Relative Strict Priority

In the relative strict-priority configuration in Figure 13 on page 60, the scheduler provides relative strict-priority scheduling relative to the VC. If the port is not oversubscribed, the VC round robin does not cause significant latency.

Figure 13: Relative Strict-Priority Configuration

This configuration provides a latency bound for the relative strict-priority queues. The worst-case latency caused by a nonstrict packet is the propagation delay of a single large packet at the VC rate. For a 1500 byte frame at a 2 Mbps rate, that delay is about 6 milliseconds.

This configuration provides for shaping the aggregate of nonstrict and relative strict packets to a single rate, and it is consistent with the traditional ATM model. It does not scale as well as true strictpriority,because the nonstrict and relative strict traffic together must not oversubscribe the port rate.

Relative Strict Priority on ATM Modules

You can use relative strict priority on any type of E Series line module; however, on ATM line modules you have an alternative. On ATM line modules you can configure true strict-priority queues in the HRR scheduler and shape the aggregate for the VC in the SAR scheduler. VC backpressure affects only the nonstrict traffic for the VC. For this type of configuration, you should shape the relative strict traffic for each VC in the HRR

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scheduler to a rate that is less than the aggregate VC rate. This shaping prevents the VC queue in the SAR scheduler from being congested with strict-priority traffic.

The major difference between relative and true strict priority on ATM line modules is that relative strict priority shapes the aggregate for the VC to a pre–cell tax rate, whereas true strict priority shapesthe aggregate for theVC to a post–cell tax rate. For example, shaping the VC to 1 Mbps in the HRR scheduler allows 1 Mbps of frame data, but cell tax adds anywhere from 100 Kbps to 1 Mbps additional bandwidth, depending on packet size. Shaping the VC to 1 Mbps in the SAR scheduler allows just 1 Mbps of cell bytes regardless of packet size.

Oversubscribing ATM Ports

You cannot oversubscribe ATM ports and still achieve low latency with relative strict-priority scheduling. There are several ways to ensure that ports are not oversubscribed. The most common is to use a per-VC scheduler by configuring the HRR scheduler with either ATM VP or VC node shaping (using the atm-vp node or atm-vc node commands), and setting the sum of the shaping rates less than the port rate. In these scenarios, the cell residency in the SAR scheduler is minimal, and cell scheduling does not interfere with relative strict priority.

Minimizing Latency on the SAR Scheduler

There are two methods you can use to control latency on the SAR scheduler. In the first method, you set the ATM QoS port mode to low-latency mode. In low-latency mode, the HRR scheduler controls scheduling, buffering in the SAR scheduler is limited, and latency caused by the SAR scheduler is minimized.

You can also use the default no qos-mode-port mode of SAR operation to minimize the latency induced by the SAR. In this method, you set qos shaping-mode cell and shape an OC-3 ATM port to 149 Mbps, or an OC-12 ATM port to 600 Mbps. By throttling the rate at which the HRR scheduler delivers packets to the SAR, you bound SAR buffering and latency. This approach retains the flexibility to configure different ATM QoS in the SAR, including shaped VP tunnels, UBR+PCR, nrtVBR, and CBR services.

To set the SAR mode, use the qos-mode-port command. For more information about operational modes on ATM interfaces, see “ATM Integrated Scheduler Overview” on page 151.

NOTE: Controllinglatencyis not normally required. If you undersubscribe the

port rate in the HRR scheduler, you can obtain latency bounds without modifying the SAR mode of operation.

HRR Scheduler Behavior and Strict-Priority Scheduling

The HRR schedulerdoes notoffer native strict-priority schedulingabove the firstscheduler level in the hardware; however, you can configure very large weights in the round robin in the HRR scheduler to obtain approximate strict-priority scheduling. Note that under conditions of lowVC bandwidth and large packet sizes, latency and jitter increase because of theinherent propagationdelay of large packets over a smallshaping rate.The following

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sections describe additional configuration steps that will ensure that no more than a single nonstrict packet can precede a strict-priority packet on the VC.

Zero-Weight Queues

To reduce latency and jitter, you can configure the relative strict-priority queue with a weight of 0 (zero), which gives the queue a weight of 4080. When a packet arrives at a zero-weighted queue, the queue remainsin the active WRR until it is exhausted, whereas competing queues must leavethe active WRR becausetheir weight credits are exhausted. To completely drain the queue, configure the maximum burst size. The zero-weighted queue is eventually alone in the active round robin and is effectively drained at strict priority.

To configure more than one relative strict queue or node, simply configure a maximum weight, and the two relative strict queues or nodes will share bandwidth fairly. You can shape the nonstrict queue, as described in the next section, to keep latency bounded.

Also, configure only a few nonstrict nodes or queues to prevent additional latency and jitter of the relative strict-priority traffic when the nodes or queues are in the round robin and a packet arrives in the zero-weighted queue. The number of nonstrict frames that precede a relative strict frame equals the number of nonzero weighted queues among the sibling scheduler nodes.

Nonstrict queues muststill exhaust theirweight credits before they leavethe active round robin. The result is thatoccasionally more thanone nonstrictframe may precede a relative strict frame, causing more jitter than may be acceptable. You can eliminate this source of latency by shaping the nonstrict queue to the aggregate rate with a burst size of 1.

Setting the Burst Size in a Shaping Rate

The burst value in a shaping rate determines the number of rate credits that can accrue when the queue or scheduler node is held in the inactive round robin. When the queue is back on the active list, the accrued credits allow the queue or node to catch up to the configured rate, up to the burst value.

Normally, the burst size is several packet lengths to allow a queue deprived of bandwidth because of congestion to catch up to its rate. Larger burst sizes allow more bursting to allow the queue to attain its shaped rate under bursty congestion scenarios.

Special Shaping Rate for Nonstrict Queues

To remove additional jitter, you can configure the nonstrict queue with a special shaping rate that causes the hardware to temporarily eject the queue from the active round robin whenever it sends a frame. The result is that at most one nonstrict frame can precede a relative strict-priority frame. The special shaping rate is the same rate as the aggregate rate, but with a configured burst size of 1.

You can still configure a shaping rate for the zero-weighted queue or node. This is useful for limiting starvation of the nonstrict traffic in the aggregate.

In Figure 14 on page 63, the VC node is shaped in the HRR scheduler to 1 Mbps to limit the aggregate traffic for the subscriber. The relative strict traffic is shaped to 500 Kbps.

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Chapter 8: Configuring Strict-Priority Scheduling

This shapinglimits relative stricttraffic to 500Kbps, andpreventsthe relativestrict-priority traffic from starving out the nonstrict traffic.

The third shaper, on the nonstrict queue, is subtle. The rate is 1 Mbps, which allows the nonstrict traffic to consume up to the full aggregate rate of the VC. But the burst size is 1, which causes the nonstrict queue to always yield to the relative strict-priority queue after sending a packet. This burst size limits the number of nonstrict packets that can precede a relative strict-priority packet to the minimum, one packet.

Figure 14: Tuning Latency on Strict-Priority Queues

Documentation

Strict-Priority and Relative Strict-Priority Scheduling Overview on page 57•

• Configuring Strict-Priority Scheduling on page 63

• Relative Strict-Priority Scheduling Overview on page 58

Configuring Strict-Priority Scheduling

To configure strict-priority scheduling:

1. Configure the traffic classes.

host1(config)#traffic-class Low-loss-1 host1(config-traffic-class)#exit host1(config)#traffic-class Low-latency-1 host1(config-traffic-class)#exit host1(config)#traffic-class Low-latency-2 host1(config-traffic-class)#exit

2. Configure the auto-strict-priority traffic-class group, and add the traffic classes that

must receive strict-priority scheduling to the group.

host1(config)#traffic-class-group Strict-priority auto-strict-priority host1(config-traffic-class-group)#traffic-class Low-latency-1 host1(config-traffic-class-group)#traffic-class Low-latency-2 host1(config-traffic-class-group)#exit

3. Create a scheduler profile for strict-priority traffic and configure the shaping rate.

host1(config)#scheduler-profile strictPriorityBandwidth host1(config-scheduler-profile)#shaping-rate 20000000 host1(config-scheduler-profile)#exit

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4. Configure a QoS profile.

host1(config)#qos-profile Example-qos-profile host1(config-qos-profile)#atm group default host1(config-qos-profile)#atm group Strict-priority scheduler-profile

strictPriorityBandwidth

host1(config-qos-profile)#atm-vc node group default host1(config-qos-profile)#atm-vc node group Strict-priority host1(config-qos-profile)#atm-vc queue traffic-class best-effort host1(config-qos-profile)#atm-vc queue traffic-class Low-loss-1 host1(config-qos-profile)#atm-vc queue traffic-class Low-latency-1 host1(config-qos-profile)#atm-vc queue traffic-class Low-latency-2 host1(config-qos-profile)#exit

5. Attach the QoS profile to an interface.

host1(config)#interface atm 2/0 host1(config-if)#qos-profile Example-qos-profile host1(config-if)#exit host1(config)#

This configuration creates the hierarchy shown in Figure 15 on page 64.

Figure 15: Sample Strict-Priority Scheduling Hierarchy

Documentation

Strict-Priority and Relative Strict-Priority Scheduling Overview on page 57•

• For more information about specifying an expression that you can reference within a

scheduler profile, see Using Expressions for Bandwidth andBurst Values ina Scheduler Profile on page 48

• group

• node

• qos-profile

• queue

• scheduler-profile

• shaping-rate

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Chapter 8: Configuring Strict-Priority Scheduling

• strict-priority

• traffic-class

• traffic-class-group

Configuring Relative Strict-Priority Scheduling for Aggregate Shaping Rates

To configure relative strict priority scheduling for aggregate shaping rates:

1. Create a scheduler profile for the strict-priority queue.

host1(config)# scheduler-profile relativeStrict host1(config-scheduler-profile)# shaping-rate 500000 host1(config-scheduler-profile)# weight 0 host1(config-scheduler-profile)# exit

Configuring the weight of 0 reduces latency and jitter.

2. Create a scheduler profile for the nonstrict best-effort queue.

host1(config)# scheduler-profile be host1(config-scheduler-profile)# shaping-rate 1000000 burst 1 host1(config-scheduler-profile)# weight 8 host1(config-scheduler-profile)# exit

TIP: If you need to impose a shaping rate on the nonstrict queues to meet a functional requirement, you can specify a rate less than the aggregate rate. The key is that the burst size must be one, or small. The burst size determines the maximum-sized packet that can squeeze in front of a relative strict-priority packet in the round robin.

3. Create a scheduler profile for the aggregate bandwidth.

host1(config)#scheduler-profile vcAggregate host1(config-scheduler-profile)#shaping-rate 1000000 host1(config-scheduler-profile)#exit

4. Create a QoS profile, configure node shaping for each queue, and add each of the

queues to the QoS profile.

host1(config)# qos-profile relative-strict-aggregate host1(config-qos-profile)# atm-vc node scheduler-profile vcAggregate host1(config-qos-profile)# atm-vc queue traffic-class best-effort

scheduler-profile be

host1(config-qos-profile)# atm-vc queue traffic-class voice scheduler-profile

relativeStrict host1(config-qos-profile)# exit host1(config)#

This configuration creates the hierarchy shown in Figure 16 on page 66.

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Figure 16: Sample Relative Strict-Priority Scheduler Hierarchy

Documentation

• Strict-Priority and Relative Strict-Priority Scheduling Overview on page 57

• For more information about specifying an expression that you can reference within a

scheduler profile, see Using Expressions for Bandwidth andBurst Values ina Scheduler Profile on page 48

• node

• qos-profile

• scheduler-profile

• shaping-rate

• weight

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CHAPTER 9

Shared Shaping Overview

This chapter providesinformationfor configuring shared shapingof traffic on theE Series router.

QoS topics are discussed in the following sections:

•

Shared Shaping Overview on page 67

•

Shared Shaper Terms on page 68

•

How Shared Shaping Works on page 69

•

Guidelines for Configuring Simple and Compound Shared Shaping on page 70

Shared Shaping Overview

In theJunosE Software QoS implementation, you configure a traffic-classgroup to create a separate scheduler hierarchy. Traffic classes in a traffic-class groupare queuedthrough a scheduler hierarchy dedicatedto that group. QoSsupports upto five user-configurable, named traffic-classgroups. Traffic classes that donot belong to any namedgroup belong to the default traffic-class group. With the factory default configuration, the best-effort traffic class is in the default traffic-class group.

Shared shaping is a mechanism for shaping a logical interface's aggregate traffic to a ratewhen the traffic for thatlogical interface is queued through morethan one scheduler hierarchy. For example, a service provider can configure QoS for voice, video, and data traffic on a single ATM VC. The video traffic and the voice traffic are placed in separate scheduler hierarchies from the data traffic to provision the low latency that is required for voice traffic and the higher bandwidth that is required for video traffic.

In this scenario, the data traffic needs to be dynamically shaped so that its rate matches the bandwidth available after the voice and video bandwidth requirements are met. When less voice and video traffic is being forwarded, then the data traffic can expand to fill the line rate.

When determining a shared shaping rate, the system includes all bytes in Layer 2 encapsulations. The packets that are included in the rate depend on the node specified. For example, rates for an Ethernet node include the Ethernet and VLAN encapsulations.

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Shared shaping is typically enabled on theaccess-facing linemodule, but you can enable the feature for any interface type recognized by QoS, on any linemodule and any E Series Broadband Services Routers.

Documentation

• Compound Shared Shaping Overview on page 95

Shared Shaper Terms

Table 6 on page 68 defines terms used in this discussion of shared shaping.

Table 6: Shared Shaper Terminology Used in This Chapter

Simple Shared Shaping Overview on page 75•

Constituent

Active constituent

Inactive constituent

Shared Shaping

DescriptionTerm

Scheduler node or queue associated with a logical interface. A sharedshaper is configured for a logical interface; all queues and scheduler nodes associated with that logicalinterface are constituents of the shared shaper.

Constituent that is monitored or controlled by the shared shaper mechanism.

Constituent that is ignored by the shared shaper mechanism. Inactive constituents canbe indirectly controlled; for example, queues stacked above a node that is an active constituent.

Mechanism for shaping a logical interface's aggregate traffic to a rate when the traffic for that logical interface is queued through more than one scheduler hierarchy.

Documentation

Implicit shared shaper

Explicit shared shaper

Compound shared shaping

Simple shared shaping

For definitions of other common QoS terms, see QoS Terms on page 5•

Shared shaper where the system automatically selects the active constituents. The system selects scheduler nodes as active; queues above nodes remain inactive.

Shared shaper where you select the active constituents by issuing the shared-shaping-constituent command in a scheduler profile.

Hardware-assisted mechanism that controls bandwidth for all active constituents.

Software-assisted mechanism thatmeasures therateof active constituents, and shapes the rate of the best-effort node or queue to the residual shared-shaping rate.

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How Shared Shaping Works

You can configure the shared-shaping rate on either the best-effort scheduler node or the best-effort queue for the logical interface. The router also locates the queues in named traffic-class groups that are associated with the logical interface and shapes that set of queues to the shared rate. The shared-shaping rate is the total bandwidth for the logical interface.

A typical configuration places the low-latency voice traffic in the auto-strict-priority traffic-class group and video traffic in a separate extended traffic-class group. The data traffic is usually queued in the best-effort traffic class in the default traffic-class group.

The constraints of both the legacy hierarchical scheduler and the shared shaper affect the bandwidth of scheduler objects. The shared shaper limits the bandwidth even when the port or VP is not congested. When the port or VP is congested, the legacy scheduler is dominant. For example, when a heavily oversubscribed VP becomes congested, the legacy hierarchical scheduler may limit the VP bandwidth to a lower rate, so that shared shaping of excess bandwidth does not apply.

Chapter 9: Shared Shaping Overview

When determining the shared-shaping rate, the system includes all bytes in Layer 2 encapsulations. The packets that are included in the rate depend on the Layer 2 node that is specified in the QoS profile. For example, the shaping rate for an Ethernet node includes bytes from the Ethernet and VLAN encapsulations.

Two types of shared shaping are available, depending on your hardware. Simple shared shaping can shape the best-effort node or queue associated with a logical interface to a shared rate. Compound shared shaping is a hardware-assisted mode that controls bandwidth for all scheduler objects associated with the subscriber logical interface.

Table 7 on page 69 compares the two types of shared shaping that are available.

Table 7: Comparison of Simple and Compound Shared Shaping

AdvantagesShared Shaper

•

Simple

Compound

Simple shared shapingis useful fortriple-play configurations, because it manages voice and video queues in addition to data queues so that the shared rate cannot be exceeded.

•

You can use line modules that have any ASIC hardware.

•

Compound shared shaping is useful for triple-play configurations, because it manages voice and video queues in addition to data queues so that the shared rate cannot be exceeded.

•

Compound shared shaping responds to changes in traffic rates more rapidly than simple shared shaping, in the order of milliseconds.

•

You can useline modules with theEFA2ASIC or theTFA ASIC.

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Active Constituents for Shared Shaping

When you specify a shared-shaping rate on a best-effort node or queue, QoS shapes the aggregate of traffic for the logical interface that owns the best-effort queue or node. QoS locatesthe queues andnodes owned by thatlogicalinterfaceand applies theshared shaper to them. The nodes andqueues owned bythe interface are called the constituents of the shared-shaper instance. For example, if the logical interface type is VC, the constituents are all VC objects: VC nodes and VC queues. A shared-shaping rule in a profile can apply to up to eight constituents.

Active constituents are actively controlled by the shared-shaper mechanism. Inactive constituents are indirectly controlled. For example, when ATM VC queues are stacked above an ATM VC node, the ATM VC node might be an active constituent. In this case, the queues stacked above the node are shaped to the shared rate indirectly by the hierarchical scheduler. If the ATM VC queues are the active constituents, then the ATM VC node is inactive.

Documentation

Simple Shared Shaping Overview on page 75•

• Compound Shared Shaping Overview on page 95

• Constituent Selection for Shared Shaping Overview on page 103

Guidelines for Configuring Simple and Compound Shared Shaping

When you configure shared shaping, be sure to consider the following behaviors.

Shared Shaping and Individual Shaping

You can use both the shared-shaping-rate command and the shaping-rate command in a single scheduler profile. For example, you can shape the best-effort node or queue to accept less than the remainder of the shared-shaping rate as in the following commands:

(config)#scheduler-profile shared-1mbps (config-scheduler-profile)#shared-shaping-rate 1000000 simple (config-scheduler-profile)#shaping-rate 500000

If you configure a shaping rate higher than the shared-shaping rate, the rate never exceeds the shared rate, so the router issues the following error message:

% shaping-rate cannot be greater than the shared-shaping-rate

Although you can configure a shared-shaping rate and a shaping rate in the same scheduler profile, the shaping rate mustnot exceed the shared-shaping rate. A scheduler profile that includesa shaping rate must not contain a shared-shaping rate that specifies a constituent as weighted.

Shared Shaping and Best-Effort Queues and Nodes

A scheduler profile that includes a shared-shaping rate cannot be associated with a queue other than the best-effort queue or a node other than the best-effort node.

Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - QUALITY OF SERVICE CONFIGURATION GUIDE 2010-09-22, JUNOSE 11.3 Configuration Manual

Specifications and Main Features

Frequently Asked Questions

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