Page 1
Promina® Series
Multiservice Access Platform
ATM Modules
Page 2
Part Number: 037035-405 Rev A
Copyright © 2009 Network Equipment Technologies, Inc. All rights reserved.
NETWORK EQUIPMENT TECHNOLOGIES, INC. (hereinafter referred to as "N.E.T."), PROVIDES THIS
DOCUMENT AS IS, WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPO SE.
No part of this publication may be stored in a retrieval system, transmitted or reproduced in any way, including photocopy, photograph, magnetic, or other record, without the prior written permission of N.E.T. Unpublished-rights
reserved under the copyright laws of the United States.
Trademarks
The N.E.T. logo, PanaVue, PrimeSwitch, Promina, SCREAM, Service Creation Manager, and SHOUTIP are
registered trademarks, and CellXpress, FrameXpress, Frame Relay Exchange, IPNX, LAN/WAN Exchange, Network
Equipment Technologies, N.E.T., the net.com logo, net.com, netMS, PortExtender, PrimeVoice, SCREAMvue, and
SHOUT are trademarks of Network Equipment Technologies, Inc.
SunOS and Solaris software copyright is held by Sun Microsystems, Inc. Sun Microsystems is a registered trademark
and Sun, SunOS, OpenWindows, Solaris, and Ultra are trademarks of Sun Microsystems, Inc. UNIX is a registered
trademark of The Open Group.
All other trademarks and registered trademarks are the sole property of their respective owners.
This document constitutes the sole Specifications referred to in N.E.T.'s Product W arranty for the products or services
described herein. N.E.T.’s Product Warranty is subject to all the cond itions, restrictions, and limitations contained
herein and in the applicable contract. N.E.T. has made reasonable efforts to verify that the information in this document is accurate, but N.E.T. reserves the right to correct typographical errors or technical inaccuracies. N.E.T.
assumes no responsibility for any use of the information contained in this document or for any infringement of patents or other rights of third parties that may result from the use of this document. Networking products cannot be
tested in all possible uses, configurations or implementations, and interoperability with other products cannot be
guaranteed. The customer is solely responsible for verifying the suitability of N.E.T.'s products for use in its network.
Local market variations may apply. This document is subject to change by N.E.T. without notice as additional information is incorporated by N.E.T. or as changes are made by N.E.T. to hardware or software.
U.S. Government Rights, Government Users
The software accompanying this documentation is furnished under a license and may only be used in accordance with
the terms of such license. This documentation is "commercial computer software documentation" as that term is used
in 48 CFR 12.212. Unless otherwise agreed, use, duplication, or disclosure of this documentation and any related
software by U.S. Government civilian agencies is subject to restrictions as set forth in 48 CFR 52.227-14 (ALT III)
and 48 CFR 52.227-19, and use, duplication, or disclosure by the U.S. Department of Defense is subject to restrictions as set forth in 48 CFR 227.7202-1(a) and 48 CFR 227.7202-3(a) or, if applicable, 48 CFR 252.2277013(c)(1)(ii) (OCT 1988).
Released
November 2009
Network Equipment Technologies, Inc.
6900 Paseo Padre Parkway
Fremont, CA 94555 U.S.A.
http://www.net.com
ii ATM Modules
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Contents
About This Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Document Organization.....................................................................................................xv
Document Conventions.................................................................................................... xvi
Related Documents........................................................................................................ xviii
Reader Feedback.............................................................................................................. xix
Technical Assistance........................................................................................................ xix
Chapter 1 Technology Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
ATM Basics..........................................................................................................................2
Access Devices ..........................................................................................................................2
V irtual Ci rcuits........................................................................... ................................................2
ATM Traffic Concepts ...............................................................................................................4
HDLC Basics.......................................................................................................................8
Frame Relay Basics .............................................................................................................9
CellXpress Features...........................................................................................................10
Inverse Multiplexing (IMA).....................................................................................................10
LAN Internetworking...............................................................................................................10
Frame Relay to ATM Network Interworking...........................................................................10
Port Side Connectivity.............................................................................................................11
SCLX Features...................................................................................................................15
Async or Sync mode................................................................................................................15
Structured or Unstructured mode..................................................................... ..... ...................15
CBR or VBR port side connectivity ........................................................................................15
Proprietary or non-proprietary mode .......................................................................................15
Port Side Connectivity.............................................................................................................16
Recommended Additional Documentation........................................................................18
Books .......................................................................................................................................18
Internet Resources....................................................................................................................18
Chapter 2 CellXpress Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Description.........................................................................................................................20
Features....................................................................................................................................21
System Requirements...............................................................................................................21
FRF.5 Compliance ................................................................................................................... 21
CellXpress Bundle Types.......................................................................................... ..... ..... .....21
CellXpress Span Types .................................................................................... ..... .... ............... 26
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Clock Priority Overview..........................................................................................................27
TBus Bandwidth Overview................................................................................... ...................27
SCLP Overview .......................................................................................................................29
Redundancy Overview.............................................................................................................29
Traffic Shaping Overview........................................................................................................29
VBR Port Bundle Traffic Shaping.....................................................................................30
Cellification of Frames.............................................................................................................3 0
Frame Size....................................................... .... ..... ................................................................30
Shaping Options.......................................................................................................................31
Frame Relay FRF.5 Overview ...........................................................................................33
LMI Protocol ...........................................................................................................................33
Frame Relay FRF.8 Overview ...........................................................................................39
Basic Features.............................................................. ..... .......................................................39
Protocol Encapsulation ............................................................................................................39
Configuration Parameters ........................................................................................................40
Cellrate Calculations for CBR Circuits .............................................................................41
Cellrate Calculations for VBR Circuits .............................................................................42
Chapter 3 SCLX Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Description.........................................................................................................................44
Features....................................................................................................................................44
Feature Key..............................................................................................................................45
System Requirements...............................................................................................................45
SCLX Bundle Types ................................................................................................................45
SCLX Logical Span.................................................................................................................49
SCLX Physical Link ................................................................................................................49
Clock Reference Overview......................................................................................................50
TBus Bandwidth Overview................................................................................... ...................50
Bundle TBus Allocation...........................................................................................................50
SCLP Overview .......................................................................................................................50
Redundancy Overview.............................................................................................................51
Traffic Shaping Overview..................................................................................................52
Cellrate Calculations for CBR DVT Circuits ..........................................................................52
Cellrate Calculations for CBR Port Circuits............................................................................56
Reassembly Buffer Calculations for CBR Circuits..................................................................65
Cellrate Calculations for VBR Port Circuits............................................................................65
SCLX Compatibility Feature...................................................................................................66
Chapter 4 Hardware Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Hardware Components ......................................................................................................68
Interface Modules ....................................................................................................................68
Shelf Types...............................................................................................................................68
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CellXpress Front Card .......................................................................................................69
CX Front Panel.........................................................................................................................70
CellXpress Interface Cards................................................................................................71
T1 Interface Card.....................................................................................................................71
E1 Interface Card.....................................................................................................................74
T3 Interface Card.....................................................................................................................77
E3 Interface Card.....................................................................................................................79
CXI-S Interface Card...............................................................................................................80
OC-3/STM-1 Interface Card...................................................... ..............................................81
SCLX Front Card...............................................................................................................82
SCLX Front Panel....................................................................................................................83
SCLX Interface Card .........................................................................................................84
OC-3c/STM-1 Interface Card .................................................................................................. 84
Chapter 5 Hardware Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
CellXpress Installation Requirements ...............................................................................88
Load Units................................................................................................................................88
Logical Slots ............................................................................................................................88
Power Consumption.................................................................................................................88
CellXpress Module Installation .........................................................................................89
SCLX Installation Requirements.......................................................................................93
Load Units................................................................................................................................93
Logical Slots ............................................................................................................................93
Power Consumption.................................................................................................................93
SCLX Module Installation.................................................................................................94
Module Replacement.........................................................................................................99
Chapter 6 CellXpress Software Configuration . . . . . . . . . . . . . . . . . . . . . . . . . 101
Configuration Overview ..................................................................................................102
Card Installation...............................................................................................................102
Card Parameters...............................................................................................................103
Configurable Card Parameters............................................................................................... 103
OC-3 Card Installation.............................................................................................. ..... ........ 105
Query Card Fields..................................................................................................................105
Span Installation ..............................................................................................................113
Span Parameters...............................................................................................................114
Configurable Span Parameters...............................................................................................114
OC-3 Card Install / Modify Span........................................................................................... 116
OC-3 Test Card ................................................................................................ ..... ................. 116
OC-3 Loop Span ....................................................................................................... ............. 117
Query Span Fields..................................................................................................................117
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OC-3c Alarms........................................................................................................................128
Bundle Installation...........................................................................................................129
CBR Virtual Trunk Bundles.............................................................................................131
Installation Notes ...................................................................................................................131
Configurable Bundle Parameters...........................................................................................132
Query Bundle Fields ..............................................................................................................136
CBR Port Bundles............................................................................................................142
CBR Port Bundle Parameters.................................................................................................148
Query Bundle Fields ..............................................................................................................153
VBR Port Bundles ...........................................................................................................158
Configurable Bundle Parameters...........................................................................................160
Query Bundle Fields ..............................................................................................................169
CBR Direct Virtual Trunk Bundles..................................................................................176
Configurable Bundle Parameters...........................................................................................176
Query Bundle Fields ..............................................................................................................179
Local Management Interface (LMI) Processing..............................................................184
Configurable LMI Interface Parameters................................................................................ 186
Chapter 7 SCLX Software Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
SCLX Configuration Overview.......................................................................................188
SCLX Card Installation..........................................................................................................188
SCLX Card Parameters....................................................................................................189
Configurable Card Parameters............................................................................................... 189
Query Card Fields..................................................................................................................190
Logical Span Installation .................................................................................................196
Logical Span Parameters .................................................................................................196
Configurable Logical Span Parameters..................................................................................196
SCLX Test Card.....................................................................................................................197
SCLX Loop Span...................................................................................................................199
Query Logical Span Fields............................................................................... ..... .... ............. 199
Logical Span Alarms..............................................................................................................204
Bundle Installation...........................................................................................................206
CBR Direct Virtual Trunk Bundles..................................................................................207
Configurable Bundle Parameters...........................................................................................207
Query Bundle Fields .............................................................................................................. 211
CBR Port Bundles............................................................................................................218
CBR Port Bundle Parameters.................................................................................................224
Query Bundle Fields ..............................................................................................................228
VBR Port Bundles ...........................................................................................................234
Configurable Bundle Parameters...........................................................................................235
Query Bundle Fields ..............................................................................................................240
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Chapter 8 Operator Interface Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
Expert Mode Command Summary ..................................................................................248
Appendix A CellXpress Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
CellXpress Loops.............................................................................................................307
Line Loop-in ..........................................................................................................................308
Line Loop-out ........................................................................................................................309
TI/E1Cell Payload Loop ........................................................................................................310
HDLC Loopback.................................................................................................................... 311
AAL5 Loopback ................................................................... ..... .... ........................................312
CellXpress Tests...............................................................................................................313
Self Test..................................................................................................................................313
TBus Test ....................................................................................... ..... .... ...............................313
Send OAM Cell......................................................................................................................315
Appendix B CellXpress Card Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Connecting to the CellXpress Module Shell....................................................................318
General Information.........................................................................................................318
shellPromptSet.......................................................................................................................318
trace........................................................................................................................................319
AAL1 (CBR) Information ...............................................................................................320
aal1_cnts.................................................................................................................................320
aal1Show................................................................................................................................320
AAL5/FRMP (VBR) Information ...................................................................................322
aal5Show <vcci>....................................................................................................................322
frmpShow...............................................................................................................................322
frmp_query_dlci <port id>.................................................................................... .... ..... ........ 324
frmpClear...............................................................................................................................325
frmp_clear_status <port id>...................................................................................................325
poolShow 8 .............................................................. ..............................................................325
tsShow <pkt size>..................................................................................................................325
Alarms Information..........................................................................................................327
alarms.....................................................................................................................................327
counts.....................................................................................................................................329
HDLC Information ..........................................................................................................330
hdlc_tx_dcb_free_bdr_count <port id> .................................................................................330
IMA Information..............................................................................................................331
aimShow.................................................................................................................................331
imaShow.................................................................................................................................332
LMI Information..............................................................................................................334
lmiShowAll............................................................................................................................334
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lmiShow <port id>.................................................................................................................334
lmiShowAllIWF.....................................................................................................................335
lmiShowIWF <port id> , <vcci>............................................................................................335
MAPPER Information .....................................................................................................336
maprShow ..............................................................................................................................336
OC-3c Information...........................................................................................................336
oc3alarms...............................................................................................................................336
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Figures
Access Devices and Edge Node using CX ...................................................................................................2
Access Devices and Edge Node using SCLX or CX ....................................................................................2
Virtual Channel Connections (VCCs) ..........................................................................................................3
Virtual Path Connections (VPCs) .................................................................................................................4
Multiple DLCIs to One VCC – Tunneling .................................................................................................10
Multiple DLCIs to Multiple VCCs – DLCI Mapping ................................................................................11
Basic CellXpress Network Configuration ..................................................................................................11
CellXpress Transferring ATM Traffic to Promina Network ......................................................................12
ATM Across a Promina Network ...............................................................................................................13
Promina Network as an ATM Switch .........................................................................................................14
Promina Network as an ATM Switch .........................................................................................................15
Basic SCLX Network Configuration .......................................................................................................... 16
SCLX Transferring ATM Traffic to Promina Network .............................................................................16
Promina Network as an ATM Switch .........................................................................................................17
CellXpress Overview .................................................................................................................................. 20
CBR Virtual Trunk Bundles .......................................................................................................................23
CBR Direct Virtual Trunk Bundles ............................................................................................................24
CBR Port Bundles ....................................................................................................................................... 24
VBR Port Bundles ......................................................................................................................................25
Normal Spans ..............................................................................................................................................26
IMA Span (Inverse Multiplexing) ..............................................................................................................27
TBus Allocation for CBR Bundles .............................................................................................................28
Cellification of Frames ...............................................................................................................................30
LMI Protocol .............................................................................................................................................. 34
IWF — Frame Relay & IWF — IWF Configuration .................................................................................35
LMI Example Session ................................................................................................................................. 37
CBR Direct Virtual Trunk Bundles ............................................................................................................46
CBR Port Bundles ....................................................................................................................................... 47
VBR Port Bundles ......................................................................................................................................48
Logical Spans and Physical Link from Promina to SCREAM ...................................................................49
CX Front Panel ................................................................................................................
CXI-T1 Interface Card ...................................................................................... ..........................................71
CXI-E1B (Balanced) Interface Card ..........................................................................................................74
CXI-E1U (Unbalanced) Interface Card ......................................................................................................75
CXI-T3 Interface Card ...................................................................................... ..........................................77
CXI-E3 Interface Card ...................................................................................... ..........................................79
Splitter Card (CXI-S) ..................................................................................................................................80
CX OC-3 Multi-Mode and OC-3 Single-Mode I/F Cards ..........................................................................81
SCLX Front Panel ....................................................................................................................................... 83
SCLX OC-3c Single-Mode Multi-Mode Card ...........................................................................................84
CX Interface Card Installation ....................................................................................................................90
CX Front Card Installation .........................................................................................................................91
Nonredundant CXI T3/E3 Cabling to SX-2 ...............................................................................................92
SCLX Interface Card Installation ...............................................................................................................95
...........................70
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SCLX Front Card Installation .....................................................................................................................96
HSS-2 Shelf - SCLX Cabling to SXI-2, Span 0 .........................................................................................97
HSS-2 Shelf - SCLX Cabling to SXI-2, Span 0 and Span 1 ......................................................................98
CBR Virtual Trunk Bundle Installation ....................................................................................................131
CBR Port Bundle Installation ................................................................................................................... 142
VBR Port Bundle/FrameXpress Installation ............................................................................................158
VBR Port Bundle/LWX Installation .........................................................................................................159
CBR Direct Virtual Trunk Bundle Installation .........................................................................................176
SCLX Card Parameters .............................................................................................................................189
CBR Direct Virtual Trunk Bundle Installation .........................................................................................207
SCLX CBR Direct Virtual Trunk Bundle Parameters ..............................................................................207
CBR Port Bundle Installation ................................................................................................................... 218
CBR Port Bundle Parameters ...................................................................................................................224
VBR Port Bundle/LWX Installation .........................................................................................................234
VBR Port Bundle Parameters ...................................................................................................................235
T1/E1 Line Loop-in ...................................................... ..... .... ...................................................................308
Line Loop-out ........................................................................................................................................... 309
T1/E1Frame Loop .....................................................................................................................................310
HDLC Loopback ......................................................................................................................................311
AAL5 Loopback .................................................. ..... .... ............................................................................312
CellXpress Module TBus Test (Local) ......................................................... ............................................314
CellXpress Module TBus Test (Remote) ........................................................................... ..... .... .............315
OAM Cell Test .........................................................................................................................................316
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Tables
Typographical Conventions .......................................................................................................................xvi
Informational Icons ....................................................................................................................................xvi
ATM Traffic Concepts ........................................................................ .........................................................4
Maximum bundles of each type. .................................................................................................................23
Timers and Counters ..................................................................................................................................38
ATM Bandwidth Conversions ............................................................................... .... ..... .... ........................41
Async Mode Bandwidth to PCR Conversions ............................................................................................52
Sync Mode Bandwidth to PCR Conversions .............................................................................................. 54
Structured Mode Bandwidth to PCR Conversions .....................................................................................56
Unstructured Mode Bandwidth to PCR Conversions .................................................................................60
CXI-T1 DB-15M (Male) Pinouts ................................................................................................ .. ............. 73
CXI-E1U (Unbalanced) Jumper Settings ...................................................................................................76
CXI-T3 Crypto Re-Sync DB-9 Pinouts ......................................................................................................78
SCLX Power ...............................................................................................................................................85
TBus Allocation for CellXpress Bundles ...................................................................................................88
T1 Alarms .................................................................................................................................................119
E1 Alarms ................................................................................................................................................. 120
T3 Alarms ................................................................................................................................................. 120
E3 Alarms ................................................................................................................................................. 121
OC-3c Alarms ...........................................................................................................................................121
OC-3c/STS-1 Alarms ................................................................................................................................128
SCLP Rate Guidelines for CBR Bundles .................................................................................................133
OC-3c Alarms ...........................................................................................................................................204
Command Shortcuts ..................................................................................................................................248
T1 Alarms ................................................................................................................................................. 327
E1 Alarms ................................................................................................................................................. 328
T3 Alarms ................................................................................................................................................. 328
E3 Alarms ................................................................................................................................................. 328
OC-3c Alarms ...........................................................................................................................................329
Promina Series xi
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Procedures
Activating a VBR Port for LMI Processing .............................................................................................184
Cabling Logical Span 0 ..............................................................................................................................96
Cabling Logical Span 1 ..............................................................................................................................96
Cancelling a Test ......................................................................................................................................253
Configuring an HSD-2B Connection ........................................................................................................218
Configuring the FrameXpress (FRX) Connection .............................................................. ..... .... ..... ........ 158
Configuring the HSD-2 Connection .........................................................................................................142
Configuring the LWX Connection (HDLC) .............................................................................................159
Configuring the LWX Connection (HDLC) .............................................................................................234
Connecting to a CX Module .....................................................................................................................318
Deactivating a Bundle ...............................................................................................................................255
Deactivating a Card ............................................................................................... ...................................256
Deleting a Bundle .....................................................................................................................................259
Deleting a Card .........................................................................................................................................261
Deleting a Span .........................................................................................................................................263
Disabling a Bundle ...................................................................................................................................265
Disabling a Card .......................................................................................................................................266
Disabling a Span .......................................................................................................................................268
Disconnecting from a CX Module ............................................................................................................318
Enabling a Card ........................................................................................................................................270
Enabling a Span ........................................................................................................................................271
Installing a Bundle ............................................................. .... ...................................................................272
Installing a Bundle on an SCLX Module .................................................................................................206
Installing a Card ..................................................................... ...................................................................276
Installing a CellXpress Bundle .............................................. ..... ..............................................................129
Installing a CellXpress Card ................................................................ .... .................................................102
Installing a CellXpress Span .....................................................................................................................113
Installing a Front Card ...................................................................................... ..... .....................................90
Installing a Front Card ...................................................................................... ..... .....................................95
Installing a Logical Span ................................................................ ..... .....................................................196
Installing a Span ....................................................... .... ............................................................................ 278
Installing an Interface Card ................................................................. .......................................................89
Installing an Interface Card ................................................................. .......................................................94
Installing an SCLX Card ..........................................................................................................................188
Modifying a Card ......................................................................................................................................286
Modifying a Span .....................................................................................................................................288
Performing a Code Load ...........................................................................................................................301
Performing a Span Loop ...........................................................................................................................282
Querying Card Information ......................................................................................................................293
Querying Trunk Information ....................................................................................................................298
Replacing an ATM (CX or SCLX) Module ...............................................................................................99
Testing a Card ...........................................................................................................................................303
Promina Series xiii
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xiv ATM Modules
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About This Document
This document provides information about the SCLX and CellXpress modules. This document is
for use in the installation and management of the Promina Series of multiservice access platforms.
This document assumes that the user has a working knowledge of data communications, ATM, and
basic trunking and transmission concepts. The user also needs to be aware of the hazards associated
with electronic equipment and electricity, detail of which is beyond the scope of this document.
This document provides screen displays as examples of output. Because the displayed information
is dependent on each node’s configuration, the examples shown in this document may not
correspond exactly to the information displayed by another node. Differences in software releases
can also account for differences in displayed information.
Preface
Document Organization
The document contains the following sections:
• Chapter 1 Technology Basics
This chapter provides an overview of ATM and frame relay concepts.
• Chapter 2 CellXpress Overview
This chapter provides an overview of CellXpress.
• Chapter 3 SCLX Overview
This chapter provides an overview of SCLX.
• Chapter 4 Hardware Description
This chapter describes the front card and interface cards.
• Chapter 5 Hardware Installation
This chapter describes the installation and configuration of the CellXpress card, spans, and
bundles in the system database.
• Chapter 6 CellXpress Software Configuration
This chapter describes the installation and configuration of the CellXpress card, spans, and
bundles in the system database.
• Chapter 7 SCLX Software Configuration
This chapter describes the installation and configuration of the SCLX card, logical spans, and
bundles in the system database.
Promina Series Release 4.x4 xv
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• Chapter 8 Operator Interface Commands
This chapter contains the Operator Interface commands used for the configuration of modules
along with descriptions and examples.
• Appendix A CellXpress Diagnostics
This appendix describes loops and tests for CellXpress
.
• Appendix B CellXpress Card Statistics
This appendix describes how to display cell statistics of CellXpress.
Document Conventions
Table 1 shows the typographical conventions used in this docum ent.
Table 1 Typographical Conventions
Convention Description Example
boldface Names of buttons or keys you should press Enter or Alt.
Names of items on screens Select the View menu.
Text to enter into a field or dialog box In the Search field, enter 408*.
boldface courier
font
Italics Names of manuals, directories, or files SCREAM100/50 User Guide
Angle brackets Names of variables for which you must enter a
+ Press non-printing keys on the keyboard
Text to enter in a command line <hostname>:LOI> show vpi
*.*
Names of uniform resource locators (URLs) www.net.com
First use of term that is defined in the Terminology
Reference
specific value
simultaneously.
Use breakers rated for fast trip on supply
circuits.
<portId>, <circuitId>
Press Shift+F1.
Table 2 shows the icons used in this document to highligh t imp ortant information.
Table 2 Informational Icons
Icon Meaning
Highlights usage or other important information that might otherwise be overlooked.
Cautions user about potentially hazardous non-electrical situation that may result in loss
of data, or damage to files or equipment.
xvi ATM Modules
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Table 2 Informational Icons (continued)
Icon Meaning
Warns user about a potentially hazardous electrical situation that could result in serious
injury or death.
Warns user about a potentially hazardous laser or LED radiation emission that could
damage a user’s eyes.
Identifies the Safety Ground Connection on the SCREAM100 chassis.
Indicates the ESD Ground Connection on the SCREAM100 chassis.
Provides an application tip or short cut.
Indicates where to find more information about the specified topic.
The following icons are used in this document to provide important information:
Icon Description Definition
Note Directs the r ea der’s attention to important information.
Caution Provides information on how to avoid possible loss of
packet traffic or damage to files or equipment. Also, provides information on how to avoid a potentially hazardous
non-electrical situation.
Caution Provides information about how to protect against fire haz-
ards.
Warning Provides information on how to avoid a potentially hazard-
ous electrical situation that, if not avoided, could result in
serious injury or death.
W arning Provides information on how to avoid potentially hazardou s
laser or LED radiation emission that, if not avoided, can
damage your eyes.
Promina Series xvii
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Icon Description Definition
Related Documents
The following manuals in the Promina Series documentation set provide additional information.
Promina Series Manuals
Safety
System Hardware
Safety Ground Symbol
ESD Ground Symbol This symbol represents the ESD Ground Connection on the
Compliance and Safety
Promina 800 Installation
and Maintenance
NX1000 Installation and
Maintenance
This symbol represents the Safety Ground Connection connection on the Promina Series chassis. This symbol has a
circle around the outside of the icon.
Promina Series chassis. This symbol does not have a circle
around the outside of the icon.
Promina 200/400 Installation
and Maintenance
NX1000 Quick Installation
Promina 100 Installation and
Maintenance
Trunk Modules
Feature Modules
Management
Reference
Channelized Trunk
Modules
IP Modules
Port Extender Data Modules Packet Modules
Analog Voice Modules Digital Voice Modules Quad Basic Rate Interface
Node Management
Terminology Reference Quick Reference Alarms and Events
Trunk Modules ATM Modules
xviii ATM Modules
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Reader Feedback
Please send comments regarding the content of this document by Email or U.S. mail to:
tech_pubs@net.com
or
Technical Publications
N.E.T.
6900 Paseo Padre Parkway
Fremont, California 94555
N.E.T. may use or distribute any informati on s upp lied in any way it believes appropriate, without
incurring obligation to the provider of the information.
Technical Assistance
If there is a problem installing or using N.E.T. products, call N.E.T. Technical Assistance Center
(TAC) at the following numbers:
In North America, call 1.800.800.4638
For International collect calls, use 1.703.948.7999
TAC engineers are available by telephone 24 hours a day, seven days a week. Warranty and
contract customers receive first consideration in the scheduling of technical resources.
Before contacting TAC for help, review and verify the provisions contained in your warranty or
contract, as there may be a charge for service.
When authorized, TAC engineers can diagnose most network problems remotely, using dial-up
connections. When a service technician is required, TAC will dispatch the nearest N.E.T. or thirdparty service engineer.
T echnical pr oblems can be diagnosed and resolved mor e quickly if you have remote
access, such as a dial-in modem. Use a modem rated at 9600bps or greater, or an
ISDN connection, for dial-in N.E.T. TAC support and incoming PPP connections.
For other remote access methods, contact N.E.T. TAC for details.
Promina Series xix
Page 20
xx ATM Modules
Page 21
Technology Basics
The Technology Basics chapter in the ATM Modules manual describes Asynchronous Transfer
Mode (ATM) and frame relay concepts and terminology related to the ATM modules: CellXpress
(CX) and SCLX.
This chapter includes the following sections:
• “ATM Basics” in the next section
• “HDLC Basics” on page 8
• “Frame Relay Basics” on page 9
• “CellXpress Features” on page 10
• “SCLX Features” on page 15
• “Recommended Additional Documentation” on page 18
Chapter 1
This document is intended to provide SCLX and CellXpress-specific det ails
only, rather than a general explanation of ATM, frame relay, and
internetworking principles. Users unfamiliar with the protocols and
standards associated with these technologies should see “Recommended
Additional Documentation” on page 18
Promina Series 1
Page 22
ATM Basics
Promina Series
ATM Switch
CX Module
ATM Access Device
Edge Node
ATM
Network
Off-Net to any
FRF.5 Compliant
Device
ATM Access Device
Edge Node
ATM
Network
SCLX or CX Module
Promina Series
SCLX or CX Module
Promina Series
SCREAM
Switch
SCREAM
Switch
ATM Basics
This section describes basic ATM concepts that are integral to the implementation of ATM
modules.
Access Devices
The ATM modules, SCLX and CellXpress, are ATM access devices that enable the Promina Series
family of Multiservice Access Platforms (MAP) to connect to an ATM edge nod e. An ATM
module accepts diverse traffic types, such as voice, video, Frame Relay, LAN and HDLC, and
adapts and aggregates the traffic for transport across an ATM network.
Figure 1 Access Devices and Edge Node using CX
Virtual Circuits
Figure 2 Access Devices and Edge Node using SCLX or CX
ATM connections are established using Permanent Virtual Circuits (PVC) or Switched Virtual
Circuits (SVC). With a PVC, cells are routed through a predetermined path that is established when
the service is provisioned and left up indefinitely. With a SVC, the path is dynamically established
and taken down, via a signaling protocol between the access device and the ATM network. A soft
PVC is handled like a PVC by the access system used a pre-configured VPI/VCI address, but the
path of the VCC is established dynamically upon use like a SVC.
The ATM modules currently support only PVCs.
2 ATM Modules
Page 23
ATM Basics
SCLX or CX
SCLX or CX
ATM
UNI
ATM
UNI
ATM Network
VPI=112
VCI=115
VPI=124
VCI=123
VPI=122
VCI=126
VPI=117
VCI=119
VPI=118
VCI=116
VPI=113
VCI=111
VPI/VCI
An ATM cell is identified by a two-part address label consisting of a Virtual Path Identifier (VPI)
and a Virtual Channel Identifier (VCI). The VPI/VCI uniquely identifies the virtual connection
with which the cell is associated across an ATM interface.
The VPI/VCI is like the frame relay Data Link Connection Identifier (DLCI). It has local
significance only; as the circuit traverses the network, the incoming VPI/VCI is translated at each
transmission device according to the type of connection, either a Virtual Channel Connection
(VCC) or a Virtual Path Connection (VPC).
The VPI/VCI for each connection used for the ATM modules is specified as part of the software
configuration. This is explained in detail in the “CellXpress Software Configuration” on page 101.
VCCs and VPCs
Traffic is routed through an ATM network using two typ es of connection s:
• VCC. A virtual channel connection.
The end-to-end transmission path between two access devices in an AT M network. The VCI
part of the VPI/VCI identifies the individual virtual channel links, from one physical interface
to another, that comprise the VCC’ s path through the ATM network. The VCC is switched at
each ATM network device based on the VPI and VCI, so the VPI/VCI is usually different at
each transmission point. This is the type of connection used by the ATM modules.
Figure 3 Virtual Channel Connections (VCCs)
• VPC. A virtual path connection.
A collection of virtual channels routed together over the same path through the ATM
network.
A VPI is assigned to the VPC by the carrier at each physical interface. All cells tagged with
the same VPI are routed over the same path. The VPC is switched in the ATM network based
on the VPI value only; the VCI part of the cell address is ignored. This means that any VCIs
assigned by the user arrive unchanged at the destination end node. The ATM modules do not
currently support VPCs.
Promina Series
3
Page 24
ATM Basics
VCI=115
ATM
UNI
ATM
UNI
ATM Network
VCI=120
VPI=85 VPI=60
VCI=120
VCI=115
Figure 4 Virtual Path Connections (VPCs)
ATM Traffic Concepts
This section describes additional ATM concepts related to traffic management. A basic
understanding of these concepts is necessary to configure and operate the ATM modules.
Supported ATM Traffic Concepts
The ATM modules support specific ATM traffic concepts, as follows:
Table 1 ATM Traffic Concepts
ATM Feature CellXpress SCLX
Shelf STS/EXS HSS-2
P800 Series Support Models P100/P200/P400/
P800
SX-2 Connectivity Two (one redundant pair
plus shelf bandwidth)
CBR QoS Yes Yes
Maximum CBR DVT bundle size 2 Mbps 32 Mbps
Minimum CBR DVT bundle size 64 Kbps 64 Kbps
Call Type TS TS, TA (transports TBus
CBR DVT call size Restricted to Nx64 Kbps. all sizes in async mode;
CBR ATM overhead Standard AAL-1 cell
overhead
Copper interfaces 4 x T1/E1, 1 x T3/E3 not applicable
P800
Two (Two pair, but does
not use shelf bandwidth)
valid bit)
sync mode restricted to
Nx16 Kbps.
AAL-1 plus 12.5% valid
bit overhead
Optical interfaces 1 x OC-3c/STM-1;
Single-mode and Multi-
mode supported.
4 ATM Modules
2 x OC-3c/STM-1 (for
redundancy only).
Single-mode and Multimode supported.
Page 25
Table 1 ATM Traffic Concepts
ATM Feature CellXpress SCLX
ATM Basics
Bundle to Span Routing All bundles on single
optical interface
ATM UNI ILMI Yes Yes + OAM perf stats
CBR Port Bundle Yes Yes
VBR Ports Yes Yes
Maximum VBR bundle size 4 Mbps VBR 8 Mbps VBR
Minimum VBR bundle size 64 Kbps VBR 64 Kbps VBR
Frame Relay Network Interworking Yes No
Frame Relay Service Interworking Yes No
All bundles on primary
optical interface
Descriptions of ATM traffic concept features are listed below.
Constant Bit Rate (CBR)
CBR traffic is generally defined as digital information that is represented by a continuous stream of
bits, i.e., isochronous transmission where the bit rate does not change. This includes digitized
voice, video, and some serial data applications, all of which are characterized by the requirement
for guaranteed throughput rates and service levels. The ATM modules support AAL1 for CBR
traffic.
Variable Bit Rate (VBR)
VBR traffic is generally defined as information that can be represented digitally by groups of bits
rather than a single stream of bits. The bit rate changes over the duration of the circuit, as
characterized by the Sustainable Cell Rate (SCR) and Peak Cell Rate (PCR). Most data
applications, including routers (LWX) and Frame Relay (FrameXpress), generate VBR traffic.
There are two VBR service types: VBR-Real Time (VBR-RT) in which timing is required between
the source and destination, and VBR-non real time (VBR-nrt) where timing is not required.
CellXpress supports AAL5 for VBR-nrt.
Promina Series
ATM Adaption Layers (AAL)
The AAL is a collection of protocol standards for adapting the original source traffic into ATM
cells. There are five adaptation layers that support different service classes. The ATM modules
support AAL1 for CBR traffic. CellXpress also supports AAL5 for VBR traffic.
SCLX supports both structured and unstructured AAL1 cell formats. The structured cell format has
additional information to align the cell data with the Promina TBus data. Certain Promina modules
(for example: PRC, TMCP) or call types require structured support to function properly. Other
modules (for example: HSD-2B) will function properly in either mode.
CellXpress only supports structured cell formats.
Service Classes
There are four ATM classes of service; A, B, C, and D. The protocols for these different service
classes define the timing requirements between the source and destination, the bit rate (constant or
variable) and whether the service is connection-oriented or connectionless. The ATM modules
support class A for CBR traffic. CellXpress also supports class C for VBR traffic.
5
Page 26
ATM Basics
QoS Classes
Quality of Service (QoS) classes are specified in the traffic contract for a VCC or VPC, measured
from the originating end to the destination end. The traffic contract is an agreement between the
end user and the ATM network provider that defines the set of performance standards. QoS classes
are defined by measurement parameters such as cell loss rate (CLR) and cell delay variation
(CDV). Each service class supports a different QoS class to meet the needs of different
applications. Typically, the network provider guarantees a certain QoS for user traffic conforming
to the traffic contract.
Traffic Parameters
Traffic parameters are measurable characteristics that are monitored to determine whether the user
traffic conforms to the traffic contract. T raffic parameters include such items as the Peak Cell Rate
(PCR), Sustainable Cell Rate (SCR), and maximum burst size (MBS). If the user traffic does not
conform to the traffic parameters agreed upon in the traffic contract, the network provider does not
guarantee the QoS performance. Through a method called traffic shaping, users can control how
cells are processed to make them conform to the traffic parameters. CellXpress allows you to
designate up to 16 traffic shaping levels, one for each VBR virtual channel connection.
Cell Loss Priority (CLP)
The CLP bit in the ATM cell header specifies the discard priority of the cell. When this bit is set to
0, the cell priority is high. When this bit is set to 1, the cell priority is low. If the network
experiences congestion, low-priority cells are eligible for discard. CellXpress allows you to tag all
cells for a particular VC as CLP=1.
The function of the CLP bit in the ATM cell header is comparable to the Discard Eligibility (DE)
bit in the frame relay header. CellXpress supports the network interworking function that enables
the frame relay DE bit to map to the ATM CLP bit. See “Frame Relay to ATM Network
Interworking” on page 10.
User-to-Network Interface (UNI)
The User-to-Network Interface (UNI) defines the protocols required for connections between ATM
access devices and the ATM network. The ATM modules support the ATM Forum’s Specification
UNI 3.1. This term is used to describe the Customer Premises Equipment (CPE) interface to Frame
Relay networks, ATM networks, and ISDN.
Network Node Interface (NNI)
The interface between two network switches as defined by ITU-T for ATM and Broadband ISDN.
This could be two switches of two different carriers; for example between LEC ATM network and
an IEC ATM network. The ATM NNI is also designed to be efficient enough to be an interface
between ATM switches manufactured by a single vendor used in a single network. This definition
is not to be confused with the Frame Relay NNI protocol. The ATM modules do not support NNI.
Inter Working Function (IWF)
A function which determines how user data is reformatted (plus Operations Administration
Maintenance (OAM) functions) Specifically, IWF is an interface between two or more networks
using different technologies (for example, a Frame Relay network and an ATM network). In the
ATM environment, it is the functions required at the interface between the ATM network and the
other network. IWFs are standardized for internetworking with Frame Relay, Switched Multi
megabit Digital Service (SMDS), and circuit-switched networks.
6 ATM Modules
Page 27
ATM Basics
Cell Delay Variation (CDV)
One of the ATM QoS traffic parameters is the Cell Delay Variation (CDV). Constant bit rate traffic
is especially sensitive to the CDV value. SCLX and CellXpress assign an appropriate CDV value
according to the cell rate of the circuit and is not user configurable.
OAM Cells
OAM cells are injected onto a PVC to provide for circuit testing and error indications. The
maximum number of OAM cells per second is typically very small compared to the data cells for
the PVC.
SCLX allows for the OAM Cell rate to be configurable. This allows for the Peak Cell Rate (PCR)
for very high speed CBR circuits to be calculated more precisely and is configurable on a PVC
basis.
CellXpress supports a fixed OAM value.
Proprietary Cells
The SCLX has been designed to use some proprietary ATM cells to facilitate enhanced features
with N.E.T . SCREAM nodes. The Promina supports a compatability feature for use with third party
ATM nodes. When the Promina SCLX Compatibility feature key is enabled by authorized N.E.T.
service representatives, the proprietary ATM cells are not used and any standards based ATM
switch may be used with SCLX.
Reassembly Buffer
The SCLX has been designed with a storage area on the module where the CBR ATM cells are
received from the OC-3 facility. This buffer exists to accommodate expected Cell Delay Variation
(CDV). To allow for flexibility between CDV tolerance and reassembly delay, the reassembly
buffer is configurable. See “Reassembly Buffer Calculations for CBR Circuits” on page 65.
Promina Series
7
Page 28
HDLC Basics
HDLC Basics
Data Communications devices such as routers and frame switches use a layered set of protocols to
process the data they manage. In the ISO/OSI reference model, the data link layer provides a basic
packet transport mechanism between two entities exchanging data. The data link layer may be
divided into several sublayers such as the logical link control (LLC) sublayer and the media access
control (MAC) sublayer. For the purposes of understanding the way CellXpress handles transport
of the “HDLC family” of protocols, the user does not need to be concerned with these sublayers.
Other instances of HDLC like protocols include SDLC, PPP, V.120, LAPB, LAPD, Q.921, etc.
Note that the suite of Frame Relay protocols operate on a data link layer entity called a frame rather
than a packet. They are basically the same.
A summary of functions in the data link layer are as follows:
• Link establishment and termination.
• Transmits/Receives a serial bit stream to/from the physical layer
• Defers transmission when a medium is busy
• Recognizes valid packet/frames (i.e. packet/frame delineation and recovery from the serial bit
• Performs a data integrity check (e.g. CRC) on the frame.
Many integrated circuit chips available these days directly provide hardware support for the HDLC
family of protocol processing. N.E.T. PX Platform and CellXpress modules have hardware
components to process both HDLC and Frame Relay encapsulated packet traffic.
The frame usually consists of five fields:
• Flag fields
• Address field
• Control field
• Information field
• Frame Check Sequence field
There are many fine references that can provide extensive background information about HDLC
(for example, Data Link Protocols by Uyless Black, Prentice Hall, 1993).
stream)
8 ATM Modules
Page 29
Frame Relay Basics
One of the key features of CellXpress is its ability to efficiently transport frame relay traffic across
an ATM network. This section briefly describes some basic principles of frame relay technology,
including specific aspects of the FrameXpress frame relay network, that affect how CellXpress is
configured for frame relay traffic. SCLX does not support frame relay traffic.
For detailed information about the FrameXpress system, see the Frame Relay Exchange (FRX)
User’s Guide.
User-to-Network Interface (UNI)
FrameXpress access ports can be configured as UNI ports, supporting the ANSI, CCITT, or LMI
protocols. These ports are the entry and exit points for user and network equipment.
Network-to-Network Interface (NNI)
A FrameXpress access port can be configured as an NNI port, supporting the ANSI, and CCITT
protocols. The NNI allows for standards-based connectivity to other public or private frame relay
networks.
Data Link Connection Identifier (DLCI)
The DLCI is the address that a Frame Relay device reads to determine where to send a particular
frame. The DLCI uniquely identifies a Frame Relay PVC in the same way that the VPI/VCI
identifies an ATM PVC.
It is possible to have many DLCIs per physical port, each representing one virtual circuit. DLCIs
have local significance only, so the DLCI must be unique within the same port, but not unique
across ports.
Frame Relay Basics
The FrameXpress network uses physical addresses (node-card-port) to set up virtual connections. A
request for a new connection is always in terms of a source node-card-port to a destination nodecard-port. The user assigns DLCIs at each originating access port, while the DLCIs at internodal
ports are automatically assigned along the designated PVC.
Discard Eligibility (DE) Bit
The DE bit in the frame header is used to mark frames that are discarded first during congested
periods. When using CellXpress to map frame relay connections to ATM VCCs, the DE bit is
mapped to the ATM cell CLP bit. For more information, see “[24] CLP Mode” on page 135.
Promina Series
9
Page 30
CellXpress Features
VCC
ATM Network
CellXpress
FrameXpress
Data Module
Router
CellXpress Features
This section briefly describes the basic features available in CellXpress.
Inverse Multiplexing (IMA)
For CellXpress, the Inverse Multiplexing for A TM (IMA) feature allows up to four T1 or E1 spans
to be grouped together to provide a higher bandwidth aggregate span. It provides a cost-effective
and flexible method of transporting ATM traffic at rates greater than T1/E1, without requiring a T3/
E3. CellXpress currently supports the ATM inverse multiplexing specification developed by
StrataCom, Inc™ as well as ATM Forum compli ant IMA.
For more information about the IMA feature, see “IMA Spans” on page 26.
LAN Internetworking
CellXpress encapsulates the HDLC frames into cells for transport across the ATM network.
For information on transporting HDLC traffic, see “VBR Port Bundles” on page 25 .
Frame Relay to ATM Network Interworking
Frame Relay to ATM Network Interworking is the integration of frame relay and ATM networks.
CellXpress supports the Network Interworking Function (IWF) as defined in the Frame Relay
Forum FRF.5 and FRF.8 standards.
The FRF .5 feature provides two methods for transporting frame relay traffic transparently across an
ATM network:
• Many to One or Tunneling—multiple frame relay connections from FrameXpress UNI or
NNI ports (or any FRF.5 compliant device) are mapped to a single VCC and sent through the
ATM network to CellXpress (or a FRF.5 compliant device) at the far end. The individual
frame relay DLCIs are ignored. This feature is implemented using VBR port bundles. For
more information, see “VBR Port Bundles” on page 25.
Figure 5 Multiple DLCIs to One VCC – Tunneling
10 ATM Modules
Page 31
CellXpress Features
CellXpress
FrameXpress
Data Module
CellXpress
FrameXpress
Data Module
FRAD
DLCI
VCC
ATM Network
DLCI
DLCI 16
DLCI 25
16
25
Router
Router
Router
CellXpress
CellXpress
ATM Network
PX-3
PX-3
• Many to Many or DLCI Mapping—multiple frame relay connections, as identified by the
DLCIs, are mapped to multiple VCCs on the CellXpress and sent through the ATM network
to CellXpress modules (or any FRF.5 compliant device) at the remote end.
Figure 6 Multiple DLCIs to Multiple VCCs – DLCI Mapping
The FRF.8 feature provides for transporting frame relay traffic across an ATM network and
terminating on a ATM device (i.e. not a Frame Relay device). This Frame Relay to ATM protocol
translation is supported by CellXpress.
Port Side Connectivity
Before the introduction of CellXpress port side connectivity, CellXpress could function only as an
access device onto an ATM network. The most common configuration is to take IP traffic from a
PX card and put it onto an ATM network, as shown in Figure 12:
Figure 7 Basic CellXpress Network Configuration
Port side connectivity enables CellXpress to function in the opposite direction. The CellXpress is
able to aggregate ATM traffic and transfer it to a Promina network. In essence, a Promina network
Promina Series
11
Page 32
CellXpress Features
CellXpress
CellXpress
Promina
Network
ATM
Network
ATM
Network
can be part of the ATM cloud. Several new network configurations are possible; Figure 8 shows
one example:
Figure 8 CellXpress Transferring ATM Traffic to Promina Network
Supported Configurations
The following configurations are supported by CellXpress port side connectivity:
• VBR Port Bundle to VBR Port Bundle Calls
• CBR Port Bundle to CBR Port Bundle Calls
VBR Port Bundle to VBR Port Bundle Calls
To set up a call between two CellXpress VBR Port Bundles acro ss a Promina cloud, one bundle
must be configured as Ans-Only, and the other one as Orig-Only. The originating port bundle uses
the NxCyPz nomenclature to refer to the destination bundle. This is consistent with the way the
HSD-2/PRC/TMCP ports communicate with any other destination port. For example, when
connecting to bundle N200C18B13, the originating bundle will use N200C18P13 as the destination
port.
In order for a call to come up between two VBR Port bundles, the following parameters must
match:
• Peak Data Rate
• Port Mode (HDLC or Frame Relay)
If the VBR port bundle is in Frame Relay mode, the user must ensure that Frame relay Local
Management Interface (LMI) is set up correctly and the FR DLCIs are mapped correctly between
the two bundles. The Promina software does not do any DLCI-level checking for mapped VBR
Port Bundles in Frame Relay mode.
CBR Port Bundle to CBR Port Bundle Calls
Calls between two CBR Port Bundles follow the NxCyPz nomenclature as well. The only
parameter of interest is the Peak Data Rate. It has to be the same on both bundles.
12 ATM Modules
Page 33
CellXpress Features
Trunk E3
Trunk E3
Promina
Network
ATM
Network
ATM
Network
CellXpress
CellXpress
Node 200Node 100
RouterRouter
VBR Bundle
VBR Bundle
Sample Network Configurations
ATM across a Promina network
Figure 9 shows ATM traffic passing through a Promina network. The Promina network consists of
regular E3 trunks. A VBR Port Bundle on Node 100 is connected to another VBR Port Bundle on
node 200. The call is going across a regular Promina T3 interface.
If the span is broken, OAM data is sent in both directions to inform the rest of the
network that the route is broken. However, OAM data is terminated at the
CellXpress card and not passed onward.
Figure 9 ATM Across a Promina Network
Promina Series
ATM traffic is terminated at the CellXpress card; both the backplane and Promina
network traffic is SNMP data, not ATM.
Promina as a “switch”
When CellXpress port bundles can connect to one another, this opens up the possibility of using the
Promina as an ATM switch. Cell traffic going into one CellXpress can go out of another CellXpress.
This is a basic “switch.” The connection between the two CellXpress’ is held constant at the peak
13
Page 34
CellXpress Features
ATM
Network
ATM
Network
ATM
Network
CellXpress
CellXpress
Node 200Node 100
RouterRouter
CellXpress
CellXpress
data rate. This configuration is useful for a customer who has a large Promina network and wants to
leverage it to do minimum ATM switching. Figure 14 shows an example of such a network:
Figure 10 Promina Network as an ATM Switch
14 ATM Modules
Page 35
SCLX Features
ATM
Network
ATM
Network
SCLX
CX
Node 200Node 100
RouterRouter
SCLX
SCLX
ATM
Network
SCREAM
SCREAM
This section briefly describes the basic features unique to SCLX.
Async or Sync mode
CBR traffic from Promina voice and data modules, such as a PRC/TMCP or HSD-2B, can be
passed to SCLX which multiplexes the calls into bundles. All call speeds can be supported
(including non-Nx64 Kbps) if async mode is selected. TBus valid bits are transported in async
mode taking additional bandwidth on the ATM facility. If sync mode is selected, the calls are
limited to trunk synchronous calls that are Nx16 Kbps. No TBus valid bits are transported in sync
mode thereby saving bandwidth.
Structured or Unstructured mode
CBR traffic can be formatted in two different ways in the ATM cell. Structured mode takes a small
amount of ATM cell bandwidth to include an additional pointer in the ATM cell. This aids in
alignment to the Promina TBus data which is required for certain types of calls or call types. It is
required for TMCP or PRC calls. For HSD-2B calls either value would be acceptable. Selection in
that case may depend on the destination port requirements.
SCLX Features
CBR or VBR port side connectivity
Port side connectivity is enabled using either AAL1 (CBR) or AAL5 (VBR) traffic characteristics.
SCLX only supports HDLC encoded packet traffic. Frame Relay internetwork ing is not supported.
Proprietary or non-proprietary mode
SCLX may be set to proprietary or Compatibility mode by a Promina node feature key. In
proprietary mode, SCLX may only be used to connect to N.E.T. SCREAM nodes. Special ATM
control cells are used for successful connections. In non-proprietary mode, the proprietary ATM
cells are not used and connections may be made to third party ATM switches.
An example of the Promina network using SCLX is shown in Figure 11.
Figure 11 Promina Network as an ATM Switch
Promina Series
15
Page 36
SCLX Features
SCLX
SCLX
ATM Network
HSD-2B
HSD-2B
SCLX
SCLX
Promina
Network
ATM
Network
ATM
Network
Port Side Connectivity
Without the functionality afforded by SCLX port side connectivity, the SCLX can act only as an
internodal trunk over an A TM network. The most common configuration is to take IP traffic from a
HSD-2B module and put it onto an ATM network, as shown in Figure 12:
Figure 12 Basic SCLX Network Configuration
The addition of port side connectivity enables a CX or SCLX to function in the opposite direction.
The SCLX is able to aggregate ATM traffic and transfer it to a Promina network. In essence, a
Promina network can be part of the ATM cloud. Several network configurations are possible;
Figure 13 shows one example:
Figure 13 SCLX Transferring ATM Traffic to Promina Network
16 ATM Modules
Page 37
SCLX Features
ATM
Network
ATM
Network
ATM
Network
Node 200Node 100
RouterRouter
SCLX
SCLX
SCLX
SCLX
Promina as a “switch”
When SCLX port bundles are connected to one another, you can use the Promina as an ATM switch.
Cell traffic going into one SCLX can go out of another SCLX. This is a basic “switch.” The
connection between the two SCLXs is held constant at the peak data rate. This configuration is
useful for a customer who has a large Promina network and wants to leverage it to do minimum
ATM switching. Figure 14 shows an exampl e of such a network:
Figure 14 Promina Network as an ATM Switch
Promina Series
17
Page 38
Recommended Additional Documentation
Recommended Additional Documentation
Books
There are many good books on the basics of ATM and frame relay. Here are just a few:
• ATM Networks by Othmar Kyas, International Thom son Publishing, Boston, MA 1995
(ISBN 1-850-32128-0)—a comprehensive guide to ATM networks with practical
explanations and illustrations
• ATM, Theory and Application by David McDysan and Darren Spohn, McGraw-Hill, Inc.
1995 (ISBN 0-07-060362-6)—a thorough introduction to ATM theory and practice, including
case examples
• Frame Relay Networks, Specifications and Implementations by Uyless Black, McGraw-Hill,
Inc. 1996 (ISBN 0-07-005590-4)—a thorough introduction to frame rela y theory and
practice, including associated technologies
Internet Resources
The internet contains hundreds of sites that contain documentation on ATM and frame relay; the
following are good starting places to discover them:
• http://www.atmforum.com — contains technical information on the standards adopted by the
ATM Forum, newsletter, and links to other resources.
• http://www.frforum.com— contains technical information on the standards adopted by the
Frame Relay Forum, white papers, newsletter, and links to other resources.
18 ATM Modules
Page 39
CellXpress Overview
This chapter provides an overview of the CellXpress module and describes how it functions within
the Promina Series network. This chapter contains the following sections:
• “Description” in the next section
• “VBR Port Bundle Traffic Shaping” on page 30
• “Frame Relay FRF.5 Overview” on page 33
• “Frame Relay FRF.8 Overview” on page 39
• “Cellrate Calculations for CBR Circuits” on page 41
• “Cellrate Calculations for VBR Circuits” on page 42
Chapter 2
Promina Series 19
Page 40
Description
Promina Series
Promina Series
Non-ATM
Traffic
Non-ATM
Traffic
ATM Switch
ATM Switch
CellXpress
CellXpress
(Any off-net FRF.5 or
FRF.8 compliant
device)
TRK-3
TRK-3
Description
CellXpress is a Promina ATM access module that interconnects Promina Series nodes (or other
compatible equipment) across an ATM network, including:
• CellXpress provides intranodal connections to PX family modules, such as FrameXpress
(FRX) and LAN/WAN Exchange (LWX), or any external Frame Relay or HDLC traffic
through an HSD-2B, allowing these applications to directly utilize ATM variable bit rate
(VBR) virtual circuits.
• CellXpress can transfer data to any off-net FRF.5 compliant device as well (see “FRF.5
Compliance” on page 21 for more information).
• CellXpress can transfer CBR data to many off-net AAL1-compliant devices as well. See
“CBR Port Bundles” on page 24. Other Promina applications utilize constant bit rate (CBR)
virtual circuits through the tandem-mode TRK-3 module.
• CellXpress can multiplex different sources of Promina traffic (voice, video, and data) onto a
single ATM connection, making it possible to:
– Utilize Promina as a common broadband service access platform
– Migrate from a circuit based network to an ATM based network
– Transpor t all Promina-supported traffic types across an ATM network (see Figure 1)
Figure 1 CellXpress Overview
20 ATM Modules
Page 41
Features
Description
CellXpress provides the following major features:
• ATM User-to-Network Interface (UNI) 3.1 support.
• Constant Bit Rate (CBR), Variable Bit Rate (VBR), and Undefined Bit Rate (UBR) support
(see Note below).
• Traffic management parameters and traffic shaping.
• Quality of Service (QoS) classes.
• Conversion of CBR traffic to ATM cells using AAL1.
• Conversion of VBR Frame Relay and HDLC-family traffic to ATM cells using AAL5.
• Different types of traffic multiplexed into a single ATM stream.
• Inverse Multiplexing of one to four T1 or E1 links.
• Frame Relay to ATM network interworking (including LMI support).
• SNMP and Interim Local Management Interface (ILMI) support.
This is a general description of the interface. Refer to the pinout diagrams There is
nothing preventing the user from connecting to a UBR class of service.
System Requirements
The CellXpress module, CX, can be installed in any standard shelf of a Promina Series node. The
Promina supports up to eight non-redundant CellXpress modules, or four pairs if redundant. The
Promina 100, 200, and 400 support two non-redundant CellXpress modules, or one pair if
redundant. Redundant CellXpress modules are to be supported in a future release.
CellXpress does not perform any local ATM switching. All traffic received from the ATM
interfaces is routed across the backplane to the appropriate Promina Series modules, and all traffic
received from Promina Series modules is routed to the appropriate ATM interface using the Virtual
Channel Identifier (VCI) and the Virtual Path Identifier (VPI).
FRF.5 Compliance
CellXpress is compliant with the Frame Relay Forum FRF.5 Implementation Agreement, including
LMI. The CellXpress module supports one-to-one multiplexing whereby the user can specify how
different frame relay logical connections on the same port can be mapped to different VCCs. Also
available is many-to-one multiplexing (an extension of one-to-one multiplexing) which allows fo r
sets of frame relay logical connections to map to different VCCs.
Finally, all-to-one multiplexing is implemented, whereby all frame relay logical connections
(DLCIs) from a given port are mapped to a single VCC.
CellXpress Bundle Types
CellXpress supports ATM access through the use of virtual objects called bundles. These bundles
are implemented via Permanent Virtual Circuits (PVCs). Switched Virtual Circuits (SVCs) are not
supported at this time.
There are several types of CellXpress bundles:
Promina Series
21
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Description
• CBR Virtual Trunk Bundles—a logical trunk that multiplexes multiple Promina circuits into
one ATM virtual channel connection (VCC).
• CBR Direct VT—a logical trunk that multiplexes trunk synchronous (at 64 Kbps each)
Promina circuits into one ATM virtual channel connection (VCC) without the need for a
TRK3 module as an aggregator.
On PLM-based systems depending on the configuration of other trunks up to 5
CBR Direct Virtual trunks are supported.
• CBR Port Bundles—a direct connection between an originating PX platform, PRC and
TMCP cards, or an HSD-2B port, and a destination CellXpress port mapped to an A TM VCC.
VBR Port Bundles can be both originating and answering a call from a PX, HSD-2B, PRC
and TMCP cards.
• VBR Port Bundles—a direct connection between voice and/or data ports and a CellXpress
port. VBR Port Bundles can be both originating and answering a call from a PX, HSD-2B,
PRC and TMCP cards.
The total number of installed bundles can not exceed 32. For example, if four VBR port bundles are
defined, and four CBR port bundles are defined, then a maximum of 24 additional bundles can be
installed (for a total number of bundles equal to 32).
CBR Virtual Trunk Bundles
CBR traffic from Promina voice and data modules, such as the PRC or QASD, can be passed to the
CellXpress module through the TRK-3 tandem-mode card, which multiplexes the calls into Nx64
Kbps bundles. Each bundle is mapped to one ATM VCC. An SCLP circuit is part of this bundle.
See Chapter 1 Trunk Modules Overview of the Trunk Modules manual for a discussion of Trunk
processing and an overview of SCLP. The CellXpress module supports up to 32 CBR virtual trunk
bundles (Figure 2 ). The VCC for this CBR Vi rtual Trunk bundle must terminate on another
Promina series node.
22 ATM Modules
Page 43
PRC
HSD-2B
TRK-3
CellXpress
CellXpress
Promina Series
VCC 1
VCC 2
Promina Series
VCC 1
VCC 2
TRK-3
ATM
Network
Table 1 Maximum bundles of each type.
Number of Max Bundles Bundle Type
32 CBR Port
32 CBR VT
32 CBR DVT*
8 VBR Port Bundle
8 VBR VT
* On PLM-based systems depending on the configuration of other trunks, up to 5 CBR
Direct Virtual Trunks are supported.
Figure 2 CBR Virtual Trunk Bundles
Description
Promina Series
CBR Direct Virtual Trunk Bundles
CBR traffic from Promina voice and data modules, such as the PRC or HSD, can be passed to
CellXpress which multiplexes the calls into Nx64 Kbps bundles. Each bundle is mapped to one
ATM VCC. An SCLP circuit is part of this bundle. No TRK-3 tandem-mode card is required for
this configuration. Only trunk synchronous (Nx64 Kbps) calls can be supported. In addition, due to
the nature of ATM structured AAL1, calls which are not an integral number of DS0s cannot be
transported through the ATM network across a CBR Direct VT. SCLP is fixed at 64 Kbps.
23
Page 44
Description
PRC
HSD-2B
CellXpress
CellXpress
Promina Series
HSD-2B
PRC
CellXpress
VCC 1
VCC 2
Promina Series
VCC 1
VCC 2
ATM
Network
VCC
CellXpress
PRC
ATM Network
Bundle
AAL1
Compliant
Device
See Chapter 1 Trunk Modules Overview of the Trunk Modules manual for a discussion of Trunk
processing and an overview of SCLP. CellXpress supports up to 32 CBR direct virtual trunk
bundles (Figure 3 ).
Figure 3 CBR Direct Virtual Trunk Bundles
CBR Port Bundles
A CBR port bundle provides an ATM access path for an originating data or voice port. The
origination port can be a PX platform, HSD-2B, PRC, or TMCP module. The CBR traffic from the
Promina voice or data module is passed to CellXpress, then mapped to a VCC for transport to an
ATM network.
Unlike CBR virtual trunk bundles, CBR port bundles do not use the SCLP. CellXpress supports up
to 32 CBR port bundles. CX port bundles can originate and terminate a call. Figure 4 shows an
example of a CBR port bundle application.
Figure 4 CBR Port Bundles
24 ATM Modules
Page 45
Description
PX Platform
CellXpress
Bundle
VCC
PX Platform
CellXpress
HSD-2B
HSD-2B
Router
Router
Bundle
Bundle
Bundle
AAL1
Compliant
Device
ATM Network
Workstation with
ATM NIC
T ermination on the remote end of the ATM network can be a variety of third party ATM devices or
another CellXpress-equipped Promina node. The CellXpress conversion of CBR traffic data to
ATM cells uses a ATM Forum compliant AAL1 structured data method. Note that SRTS or
adaptive timing methods are not supported by CellXpress. It is recommended that the Promina
node be synchronized to the same clock source as the remote ATM device.
See Setting Up Reference Clock Sources on the Node in Chapter 3 Promina Clocking in the Node
Management manual for more information on setting node clock references.
VBR Port Bundles
A VBR port bundle specifies a CellXpress TBus port that can handle HDLC or Frame Relay
encoded variable bit rate traffic. It provides ATM connectivity between the Promina Series node
and either another Promina Series node or any ATM third party device that supports a compatible
HDLC or Frame Relay interworking function such as FRF.5 or FRF.8. The CellXpress VBR port
bundle can be the originating or destination port for several Promina Series modules including
HSD-2, TMCP, PRC or FRX/LWX (on the PX platform).
VBR port bundles can terminate on non-Promina devices as no proprietary data such as the SCLP
is included in the VBR port bundle. The CellXpress module supports up to 8 VBR port bundles.
See section 2-4 for more information on configuration limits.
Figure 5 shows an example of a VBR port bundle application.
Figure 5 VBR Port Bundles
VBR port bundles can terminate on processor cards (e.g. PPM). This brings in IP
traffic over an ATM network to one of the IP applications running on the nodal
controller. See the P800 Installation and Maintenance manual for instructions on
configuring an HTC port.
Promina Series
25
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Description
CellXpress
ATM
Network
B0
B1
ATM Switch
ATM Switch
B2
Any off-net FRF.5
compliant device
S3
S2
S1
S0
Any off-net AAL1
compliant device
CellXpress Span Types
A span is the connection between the physical CellXpress interface and an ATM network.
CellXpress can support multiple spans depending on the type of interface card and the type of spans
installed. A CellXpress front card module can be installed with a variety of different rear card
interfaces. There are two types of spans:
• Normal
•IMA
Each CellXpress card is configured to support only one type of span. Normal and IMA spans
cannot both be active on the same card.
Normal Spans
A normal span is a direct physical connection between a CellXpress module and a single ATM
switch. A normal span can carry multiple bundles (VCCs), all over a single physical ATM
connection to an ATM switch.
The CellXpress T1 and E1 modules support up to four normal spans, each of which can have a
different destination edge node. The T3, E3 and OC-3c/STM-1 modules support one normal span.
Figure 6 shows an example of bundles being carried on normal spans.
Figure 6 Normal Spans
IMA Spans
An Inverse Multiplexing for ATM (IMA) span is a logical connection between the CellXpress
module and one ATM switch. Unlike on a normal span, a single bundle can be routed over multiple
physical spans. This provides increased bandwidth without requiring a T3, E3 or OC-3c/STM-1
span.
IMA spans are supported on the CellXpress T1 and E1 modules, and one IMA span per module is
supported. If a card is configured to carry IMA spans, all active spans on that card are included in
the IMA group. Any span that is enabled is not included in the IMA span and can be used for alarm
monitoring.
26 ATM Modules
Page 47
Figure 7 shows an example of a bundle being carried on an IMA span.
ATM
Network
ATM Switch
B0
CellXpress
S3
S2
S1
S0
Figure 7 IMA Span (Inverse Multiplexing)
Clock Priority Overview
Each span on the CellXpress module can be used as a reference clock source to provide clocking to
the Promina network. Because more than one span may be up at one time, a priority is configu red
to determine from which span the clock reference is derived. This priority ranges from 1 to 4, with
1 being the highest priority. The priority is configurable for each span using the Clock Priority
parameter. The software will choose between equal priority spans. For more information, see “[ 0]
Backcard” on page 103.
Description
Clock sources are monitored and if the span with the highest priority becomes unavailable, the span
with the next highest priority is used. If no span is available, the card is not used as a reference
clock source.
This Clock Priority parameter specified for the spans is different from the Clock Reference Select
parameter configured for the card. The clock reference select parameter determines whether the
card provides clocking. For more information, see “[ 1] Clock Reference Select” on page 103, and
“Clk Span” on page 108.
For more information about the clock status of a node, see the Node Management manual.
TBus Bandwidth Overview
The Promina Series platform uses an internal bus called the TBus to transport data between cards in
a node. The TBus provides bandwidth across the backplane on each shelf. It is the medium for
carrying intranodal bandwidth; either a TDM trunk module or CellXpress ATM access module is
the medium for carrying internodal bandwidth.
The CellXpress module consumes up to 32 Mbps from the backplane where it is installed. On the
Promina node, an additional 32 Mbps of bandwidth is available for T3, E3, and OC-3c/STM-1
modules through a direct connection to an SX-2 spigot. Circuits are built on the SX-2 direct
connection first if it is available. For information on connecting to an SX-2 spigot, see “Hardware
Installation” on page 87. For more information on SX-2 cards, see the P800 Installation and
Maintenance manual.
Promina Series
27
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Description
Up to 32 DS0s per port/1 logical slot per port
AAL1
SAR
CBR Traffic
4xDS0 8xDS0 16xDS0 4xDS0
CellXpress Module
Port 1
Port 2
Port 3
Port 8
TRK-3
B1
B2 B3 B4
B5 B6 B7
B8
8xDS0 8xDS0 12xDS0
8xDS0
TRK-3
. . . .
HSD-2
HSD-2
HSD-2
. . . .. . . .
Bundle TBus Allocation
For the CellXpress module, TBus bandwidth is allocated to bundles on a port-by-port basis. For
VBR calls, the TBus is dynamically configured on a per call basis, with a minimum allocation of
256 Kbps. For instance, a 128 Kbps VBR call consumes 256 Kbps of TBus bandwidth.
TBus allocation for CBR bundles is organized in groups of 32 DSOs. The ATM Segment and
Reassembly (SAR) device handling CBR traffic on the CellXpress module has eight internal ports.
Therefore for CBR traffic, 2 Mbps of TBus bandwidth (one logical slot) is allocated to each of the
eight (32 DSO-wide) SAR ports. Each SAR port may carry one or more bundles spread across the
32 DS0s; however, bundles cannot be split between ports. The bundles that fit in one logical slot
will share the logical slot space.
Figure 8 shows an example of how logical slots are allocated to a series of CBR virtual trunk
bundles.
Figure 8 TBus Allocation for CBR Bundles
Figure 8 shows eight CBR virtual trunk bundles of varying sizes (4xDS0, 8xDS0, etc.), labeled B1
through B8 being transmitted to the AAL1 SAR processor on the CellXpress module. Bundles B1
to B4 are carried on port 1 and use a total of 32 DS0s. B5 to B7 are carried on port 2, using a total
of 28 DS0s and leaving four DS0s available. Since bundles are not split between ports, B8 is sent
over port 3 because it requires eight DS0s.
28 ATM Modules
Page 49
SCLP Overview
The Signaling Channel Link Protocol (SCLP) is an internodal communications channel that is
present on all trunks and bundles, except port bundles. The SCLP carries data that allows users to
configure, query, and monitor all nodes from anywhere in the network (within the local domain if
the SuperWAN feature is enabled).
Call processing (building and tearing down calls) is the most taxing function performed by the
SCLP. If a trunk goes down, the SCLP carries numerous messages to reconnect calls, as all calls
traversing that trunk are rerouted through the network over different trunks.
CBR DVT and VT bundles on the CellXpress module are capable of supporting a variable number
of calls; therefore, the bandwidth allocated to the SCLP channel is configurable. The more calls
that are supported by the trunk, the more important it is that the SCLP channel be large enough to
build and tear down calls with acceptable response times. For more information, see “[ 4] SCLP
Bandwidth” on page 133.
Redundancy Overview
For CellXpress, domain and span level redundancy is supported, although card level redundancy is
not supported.
Description
T3, E3, OC-3/STM-1 Modules with SX-2 Connections
For CellXpress T3, E3, OC-3c/STM-1 modules that are connected to SX-2 modules, domain
redundancy is supported by cabling the A domain SX ports on the T3, E3 or OC-3c/STM-1
interface cards to one of the spigots on the SX-2A and cabling the B domain SX ports on the T3, E3
or OC-3c/STM-1 interface card to the corresponding spigot on the SX-2B. Using direct SX
connections are optional, and suggested if additional bandwidth is required. See “TBus Bandwidth
Overview” on page 27.
For more information about the SX-2 module, see the P800 Installation and
Maintenance manual.
Traffic Shaping Overview
Traffic shaping is a mechanism that alters the traffic characteristics of a stream of cells while
meeting the QoS objectives, or to ensure conformance of a traffic configuration (or contract) at a
subsequent interface.
Traffic shaping on the VBR Port Bundles provides several options to the user. All of these options
consume lower PCR/SCR values, but they require the user to know the characteristics of the frame
relay/HDLC traffic being sent through the bundle. If one of the added options is used, appropriate
use of the option is important, otherwise frames may be lost.
There are now four VBR Port Bundle traffic shaping options pertaining to the Generic Cell Rate
Algorithm:
• GCRA Maximum
• GCRA Basic
• GCRA Option 1
• GCRA Option 2
Promina Series
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VBR Port Bundle Traffic Shaping
Cell Payload (48 bytes)
[.. . ]
CPCS-UU
Padding
User Data
Cell Payload (48 bytes)
Cell Payload (48 bytes)
(1-n bytes)
(0-47 bytes)
(1 byte)
Length
CPI
(1 byte)
(2 bytes)
CRC-32
(4 bytes)
VBR Port Bundle Traffic Shaping
The ATM Forum’s definition of traffic shaping is shown below:
“Traffic Shaping is a mechanism that alters the traffic characteristics of a stream of cells on a
connection to achieve better network efficiency, while meeting the QoS objectives, or to ensure
conformance at a subsequent interface. Traffic shaping must maintain cell sequence integrity on a
connection.”
For more information on the available options see “Shaping Options” on page 31. The following
sections discuss how the cellification process and how frame size can play an important part in the
that process.
Cellification of Frames
The cellification of (frame relay/HDLC) frames essentially describes how the AAL-5 SAR breaks
frames into cells for ATM transport. As illustrated in Figure 9, the padding field is used to round
the CPCS-PDU length up to the nearest multiple of 48 bytes for cellification. The padded frame is
then broken into 48-byte segments for transport as ATM payload.
A significant factor in the amount of standard ATM overhead is the packet/frame size. Each packet/
frame must start at the beginning of a cell. Each succeeding cell is filled with the packet/frame
contents until the end of the packet/frame. This final cell in the set of cells used to convey the
packet/frame is filled with a ATM Forum compliant trailer fields to the end of this cell. If the
packet/frame ends in the first byte of the final cell, then the remaining 47 bytes are AT M overhead.
This is significant (approximately 50%) if the packet/frame is small (for example, 87 bytes), but far
less of a problem (approximately 3%) if the packet/frame is large (for example, 1500 bytes).
Frame Size
Figure 9 Cellification of Frames
Generally after the frame size increase, the efficiency increases as well; however, this increase is
not continuous.
When dealing with frame size issues there are two possible conditions which you may encounter:
Same Size Frames — In this case enter the size of the user data going to CellXpress.
Variable Size Frames — In this case the B-ICI specification recommends selecting the worst case
frame size. Also, depending upon how well you know the incoming traffic pattern, you may choose
to enter a higher frame size.
More information regarding frame sizes and how they relate to shaping options is discussed in the
next section.
30 ATM Modules
Page 51
Shaping Options
Generic Cell Rate Algorithm options are available for traffic shaping on the VBR Port Bundles. All
of these options consume lower PCR/SCR traffic values, but they do require you to know the
characteristics of the frame relay/HDLC traffic being sent through the bundle. If you use one of the
these options, be careful to make appropriate use of the option, otherwise frames may be lost.
When the CellXpress application first comes up, it converts all existing bundles to use GCRA
Maximum. This also occurs in cases where you are upgrading from a previous CellXpress release.
This corresponds to the current PCR/SCR values, and should result in the operation of the bundle
being unchanged.
GCRA Maximum, as well as the previously released CellXpress application, set PCR and SCR
values based upon a worst case for frames larger than 64 bytes. It turns out that this worst-case is 87
byte frames, because that’ s the point where a third cell per frame is required to transport one byte of
payload, resulting in the waste of 47 bytes, plus the cell header.
VBR Port Bundle Traffic Shaping
GCRA Option 1 and Option 2 use the equations specified in the ATM Forum’s BICI specification, v. 2.0.
If you are unsure of which other option you want, it is recommended that you
continue to use the GCRA Maximum option.
An additional attribute for VBR port bundles is frame size. This attribute is ignored in the case of
GCRA Maximum, and is used in the three other options. The permitted range is between 64 and
4000. For HDLC traffic, numbers above 1500 are not available.
GCRA Option 1 and Option 2 use the equations specified in the ATM Forum’s B-ICI Specification,
v . 2.0. These options both take the user-specified frame size, together with the PDR and SDR rates,
and use the appropriate equation to generate PCR and SCR values. Since GCRA Maximum
assumes a worst case, the other options always produce PCR and SCR values which are less than or
equal to (but only in the case of frame size = 87 bytes) those produced by GCRA Maximum.
The equations in the specification assume constant-sized frames. Where the traffic consists of
mixed-size frames, the specification recommends selecting the worst case as the frame size.
Unfortunately, while smaller frames are generally worse than larger frames, the pattern progresses
in a sawtooth rather than linear fashion.
GCRA Basic is intended to help you with this problem. It takes the frame size you entered (which,
we learned from the B-ICI spec, should be the worst case), calculates the number of cells required
to transport a frame of that size, then calculates the frame size which for that number of cells
represents the worst case, and finally uses the equation in Option 2 (the same used by GCRA
Maximum, which assumed a frame size of 87) to calculate the PCR and SCR values. If the entered
frame size is less than 87, this option will use 87 because it’s the worst case for all sizes greater than
64.
The four VBR Port Bundle traffic shaping options are described below:
Promina Series
GCRA Maximum
This option assumes a worst case frame size of 87 bytes and uses the same formula as Option 2. All
existing bundles are automatically converted to GCRA Maximum.
31
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VBR Port Bundle Traffic Shaping
GCRA Option 1
This option uses method 1 (1-1 mapping) from the B-ICI specification to calculate both the PCR
and SCR from the PDR and SDR. The frame size for this option is manually entered.
The only difference between Option 1 and Option 2 is in the calculation of the Peak
Cell Rate numbers. If you were to have PDR equal SDR, Option 1 would calculate
a slightly lower Peak Cell Rate than Sustainable Cell Rate.
GCRA Option 2
This option uses method 2 (1-1 mapping) from the B-ICI specification and also requires you to
manually enter the frame size (similar to the GCRA Option 1).
GCRA Basic
This option uses the same formula as GCRA Option 2. This option derives a worst case frame size
from the manually entered value by calculating the number of cells required for that frame and then
determines the worst case frame size for that number of cells. The GCRA basic option is the same
as GCRA Maximum, but allows the user to set the Average Frame Length parameter.
32 ATM Modules
Page 53
Frame Relay FRF.5 Overview
CellXpress supports the Local Management Interface (LMI) signalling protocol (within the Frame
Relay interworking function), which is used for controlling the connection between the user and the
network. The LMI protocol is responsible for the following:
• Ensuring that the data link between the user and the network is active (e.g., keep alive)
• Notifying the addition and deletion of Frame Relay-PVCs
• Delivering status messages regarding the availability of the circuits
For information on how to activate a VBR port for LMI processing, refer to “Cellrate Calculations
for VBR Circuits” on page 42. Any FRF.5 compliant device uses DLCI 0 channel for the LMI. If
you were to examine the frames every DLCI 0 would be the LMI channel (this is where the
signalling rides). For more information, see the FRF.5 standard (Frame Relay/ATM PVC Network
Implementation Agreement from the Frame Relay Forum specifications).
CellXpress can support communication between CellXpress and the destination FRF.5
interworking device in one of two ways:
• Standard LMI across the ATM network
• OAM cells
Frame Relay FRF.5 Overview
LMI Protocol
The LMI protocol provides a standardized procedure for users and networks to provision PVCs
from one end to the other end. The LMI protocol allows for standard-based connectivity to other
frame relay networks.
The primary messages used at the interface consist of status (S), full status (FS), and status enquiry
(SE) messages. The purpose of these messages is to communicate information regarding the
integrity of the link, as well as the existence and current state of each PVC on the link. A definition
of each type of status message is shown below:
• Status (S) A message that describes the status of a physical link. This message is sent in
• Full Status (FS) A message that describes the status of a physical link and additionally
• Status Enquiry (SE) A message that requests the status of a link. A Status or Full Status
A set of counters and timers defined in the specification control which detail the operation and
timing of the messages being exchanged at the UNI or NNI interface. Each message is sent with a
sequence number and by checking the sequence number the remote interface can determine if
messages are being lost. On a UNI interface, the DTE (User) side sends SE messages, and the DCE
(Network) side responds with either an S or FS message. If the User requests an FS message, a
status change has occurred with one or more PVCs. Refer to Figure 10 for an illustration describing
the LMI protocol.
response to a status enquiry message.
provides the current state of all PVCs on the link.
message may be sent in response to this request.
Promina Series
33
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Frame Relay FRF.5 Overview
Network (DCE)
User (DTE)
Status (link integrity)
Status Enquiry
Status Enquiry
Status Enquiry
Status Enquiry
Status (full status)
Status (link integrity)
Status (link integrity)
T391
T391
N391
In Figure 10 two LMI sessions exist with each session maintaining its own counters and timers.
Figure 10 LMI Protocol
The procedures at the user side must include support for T391, N391, N392, and N393. The
procedures at the network side must support T392, N392, and N393. Table 2 describes the LMI
parameters.
Network-to-network information is available in the FRF.5 standard.
Note that the values can differ depending on whether it is a Frame Relay-to-IWF or IWF-to-IWF
LMI connection (refer to Figure 11 for an example of this configuration). For example, every T391
seconds, the user side sends a status enquiry message to another network. Upon broadcasting this
message, it resets its T391 timer. On average, the status enquiry message only requests a link
integrity check. Every N391 polling cycles (i.e., the interval between the status and the status
enquiry messages), the user side asks for a full status (FS) of all the PVC segments with a full status
enquiry message. In turn, the network side responds to each status enquiry message with a status
message and also resets its T392 timer.
The data in the status message contains each PVCs DLCI status. The CellXpress module essentially
retrieves the N392 errors out of the N393 events, at which time the CellXpress module declares the
link down and PVCs inactive. An error counter, similar to the N392 counter is used by the
CellXpress module to indicate the number of errors occurring during the N393. Refer to Table 2 for
more information on timers and counters. Figure 11 illustrates VCC status management within an
IWF and Frame Relay network configuration.
34 ATM Modules
Page 55
Frame Relay FRF.5 Overview
Q.933
Annex A
Q.922
Core
PHY
Q.933
Annex A
FR-SSCS
CPCS
PHY
AAL5
SAR
ATM
AAL5
IWF
Q.933
Annex A
Q.922
Core
PHY
Q.933
Annex A
FR-SSCS
CPCS
PHY
AAL5
SAR
ATM
AAL5
IWF
FR-to-IWF
ATM
CellXpress
Frame Relay
Network
Q.933
Annex A
Q.922
Core
PHY
Q.933
Annex A
Q.922
Core
PHY
FR Status
Management
(per access port)
Q.933
Annex A
FR-SSCS
CPCS
PHY
AAL5
SAR
ATM
AAL5
Q.933
Annex A
Q.922
Core
PHY
Q.933
Annex A
FR-SSCS
CPCS
PHY
AAL5
SAR
ATM
AAL5
Network
IWF
IWF-to-IWF
IWF/CX
ATM Status
Management
(OAM)
Any off-net FRF .5
compliant device
Any off-net FRF .5
compliant device
Any off-net FRF .5
compliant device
Two scenarios are visible in this illustration.
• Frame Relay -to- IWF A CellXpress module acts as the DCE (Network) moving data back
and forth between a Frame Relay network and a CellXpress module (show in left half of
Figure 11 ). In essence, the CellXpress module acts as a DTE (User) or DCE (Network)
interface, depending upon how it is configured.
• IWF-to-IWF CellXpress module exists in an NNI configuration and acts both as the DTE
(User) and DCE (Network), sending and responding to Status Enquiry messages. The data is
sent either directly to another CellXpress module or via an ATM network (as shown in the
right half of Figure 11) which eventually leads to another CellXpress module or an FRF.5
compliant device.
Figure 11 IWF — Frame Relay & IWF — IWF Configuration
Promina Series
Link Integrity Verification
Link integrity verification is dependent upon the results from two information elements, which
consists of a send and receive sequence number and is present in every LMI message.
• Send number sequence—provided by the sender and is incremented before being sent
• Receive number sequence— the last send sequence number received from the far end.
When the recipient receives a link integrity information element, it compares the receive sequence
number with its own send sequence number. A mismatch indicates an error.
35
Page 56
Frame Relay FRF.5 Overview
PVC Status
The PVC status information element is provided by the Network in response to a request for full
status (FS) and consists of each Frame Relay-PVC’s DLCI and current status, indicated through the
use of the New and Active bits. For a newly-added Frame Relay-PVC, the Network initially sets
the new bit to 1 and the active bit to 0. Once the Network receives a correct receive sequence
number, the new bit is cleared in subsequent full status reports. After the Network is satisfied that
the Frame Relay-PVC path is fully established, the active bit is set to 1. A Frame Relay-PVC is
reported as active if all of the following criteria are met:
• The Frame Relay-PVC is configured in the network.
• If the user receives a PVC status information element for a Frame Relay-PVC not currently
defined and the new bit is set to 0, it is recorded as an error and the Frame Relay-PVC is
added to the active PVCs.
• The network considers the bearer channel to be operational.
• The Frame Relay-PVC is operational within the network (i.e. no service affecting condition
exists within the network or at the remote user-to-network interface).
• The remote user, in a bidirectional LMI relationship, reports that the Frame Relay-PVC is
active by setting the active bit to 1 in a PVC status information element.
If the user equipment receives a full status (FS) STATUS message that is missing a PVC status
information element for a Frame Relay-PVC that the user equipment is currently using, the user
equipment marks that Frame Relay-PVC inactive.
Figure 12 depicts an LMI session with several PVCs. In this example, every active port has an
active LMI session between the destination and the source. The second port contains two PVCs
(DLCI 16 and DLCI 17). One end is defined as the user and the other is defined as the network. The
B stands for bidirectional. The third port from the top, carrying two PVCs (DLCI 990 and DLCI
991) is defined as both user and network. Also, between the FRF.5 compliant device and the CX
module there is one LMI session per port; consequently, there is an LMI session for each VCC
connection on the ATM side as well.
Figure 12 also shows that there is a session for every VCC on the IWF-to-IWF side as well. On the
IWF side all LMI signalling is bidirectional. Note that DLCI values can be repeated across VBR
ports. This essentially means that port 0 and port 1 can have DLCIs that are identical, so when they
36 ATM Modules
Page 57
Frame Relay FRF.5 Overview
IWF
FR-to-IWF
FR Source
CellXpress
Frame Relay
Network
PVCs
16-1023
PVC 16
PVC 17
*PVC 990
LMI
B
N
ATM
IWF-to-IWF
IWF/CX
*PVC 991
U
IWF
IWF
IWF
VCC-W
LMI
B
P7
P0
P6
P1
P3
P4
P5
U
N
B
LMI
B
VCC-X
B
B
VCC-Y
VCC-Z
P2
B
LMI
B
B
UNI 0
B
VCC-W
VCC-X
VCC-Y
VCC-Z
P2K
LMI
LMI
Network
UNI 1
UNI 2
UNI 3
Legend:
U = User (DTE)
N = Network (DCE)
B = Bidirectional
*Note: 1-to-1 Connection Multiplexing feature
to be enabled in a future release
.
go into VCCs they should be kept separate. Frame Relay PVCs from different ports may not share
a VCC.
Figure 12 LMI Example Session
Error Detection and Handling
Both the User and the Network are capable of detecting and recording errors. Events that are
considered to be errors include:
• Receipt of an invalid receive sequence number (not equal to the last send sequence number).
• Non-receipt of a message within interval T391 (User) or T392 (Network).
• The loss of a frame at layer 2 (e.g. CRC error), sometimes detected by non-receipt of a
STATUS or STATUS ENQUIRY message
• Signalling link protocol errors
Promina Series
37
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Frame Relay FRF.5 Overview
However, an Frame Relay-PVC is not deemed inactive (for example, when the User ceases
transmission and the Network sets active bit to 0) just because one of the above events occurs. Both
sides maintain an error counter. For example, if N392 of the last N393 events are in error, the
Frame Relay-PVCs across the interface are marked inactive.
Table 2 contains the values of the various timers and counters. Note that the values can differ
depending on whether it is an Frame Relay-to-IWF or IWF-to-IWF LMI connection.
Table 2 Timers and Counters
Name Range Default Where Used Purpose
N391 1-255 Frame Relay-to-
IWF:6
IWF-to-IWF:1
N392 1-10 3 User & Netwo rk N392 errors out of N393
N393 1-10 4 User & Network It takes the N392 bad
T391 5-30 secs. 10 secs. User The “keepalive” interval
User & Network*
(*only when the
network is in a
bidirectional
configuration)
The total number of intervals (how many T391s)
the device counts before
asking for a status
enquiry with a full status
report rather than a status
report.
events describes the error
threshold.
events out of N393 events
to bring down a link.
Consequently, It takes
N392good events out of
N393 events to re-establish a down link.
that has been set on the
access device. This has to
be less than the frame
relay node timing interval, T392. Nodes may be
busy doing some other
process and may need a
few more seconds to
respond to an access
equipment poll.
T392 5-30 secs. 15 secs. Network How often the device
expects to see any status
enquiry from the access
equipment.
38 ATM Modules
Page 59
Frame Relay FRF.8 Overview
FRF .8 is a specification for service interworking between Frame Relay and ATM. The interworking
function (IWF) performs the required translation.
FRF.8 has features similar to FRF.5. In both FRF.8 and FRF.5, Frame Relay traffic is converted to
ATM traffic by the IWF . The dif ference between FRF.8 and FRF .5 is the end points of a network do
not have to be Frame Relay in FRF .8, and does not have to be converted back to Frame Relay at the
other end of the network.
In FRF .8, the IWF translates Frame Relay to ATM. In FRF.5, the end points of a network have to be
Frame Relay and the IWF encapsulates Frame Relay inside ATM cells.
Basic Features
The basic features of FRF .8 involve mapping the Frame Relay header fields to the ATM cell header
fields, and the opposite of mapping ATM cell header fields to the Frame Relay fields. The fields
mapped are:
• Frame Formatting and Delimiting
• DE and CLP mapping
• Congestion Indication
•C/R Field
•DLCI Field
Frame Relay FRF.8 Overview
Protocol Encapsulation
FRF.8 provides a way for network providers to translate frame relay-encapsulated upper layer
protocols into ATM cells. Two modes are used:
• Transparent Mode -- Encapsulation is not standard but is compatible at the end points. In this
case, the IWF will do nothing. No special mapping or translation will be performed.
• Translation Mode -- Encapsulation conforms to FRF.3 and RFC1483. The encapsulated data
in frame relay is mapped into ATM cells.
Protocol encapsulation is not supported in FRF.8.
Promina Series
39
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Frame Relay FRF.8 Overview
Configuration Parameters
The Frame Relay Protocol is a new parameter in the port bundle configuration menu, as shown in
Example 1.
Example 1 Frame Relay Protocol Parameter
*** configuration parameters for CX VBR Port Bundle N150C28B10 ***
[ 0] Orig/Ans Mode = ans-only
[13] Peak Data Rate= 384K
[20] Port Mode = Frame Relay
[21] CLP Mode = NO
[24] Error Statistics Interval (min) = 15
[27] Cell Rate Mode = GCRA Max
[28] Average Frame Length (byte) = 87
[29] Interface Protocol = CCITT-NNI OAM (CCITT Network to Network Interface)
[30] DLCI Map Mode = Mapped
[31] Add VCC To Bundle
[32] Modify VCC In Bundle
[33] Delete VCC In Bundle
Enter parameter index (or hit RETURN to continue)
PARAMETER INDEX = 31
Enter The VPI [255]
VPI = 46
Enter The VCI [255]
VCI = 110
*** Parameters for VCC [VPI = 46, VCI = 110] ***
[ 0] VCC Peak Data Rate = 384K
[ 1] VCC Sust. Data Rate = 128K
[ 2] VCC Span ID = *** NONE ***
[ 3] VCC Max Burst Time = 0.2s
[ 4] DLCIs ( *** NONE *** )
[ 5] Frame Relay Protocol = FRF.5
Enter parameter index (or hit RETURN to continue)
PARAMETER INDEX = 5
[ 0] *FRF.5
[ 1] FRF.8
NOTE: ’*’ marks default selection.
Enter Frame Relay Protocol[FRF.5]
Frame Relay Protocol =
40 ATM Modules
Page 61
Cellrate Calculations for CBR Circuits
This section describes how to calculate the size of an ATM virtual circuit for a CellXpress CBR
virtual trunk bundle. The peak data rate of the bundle is converted to the peak cell rate (PCR).
T ypically, it is the PCR that is required when configuring a virtual circuit on an ATM switch.
Use this equation to calculate the PCR:
(peak data rate/8 bits per byte)/46.875 payload bytes per cell = cells per second
For example, if the peak data rate is 512,000 bps:
(512000/8)/46.875 = 1365 cells per second
Table 3 lists the peak cell rate and ATM bandwidth equivalents for some common bundle payloads.
Table 3 ATM Bandwidth Conversions
Cellrate Calculations for CBR Circuits
Peak Data Rate (bps)
64000 171 72363
128000 341 144725
256000 683 289451
384000 1024 434176
512000 1365 578901
768000 2048 868352
832000 2219 940715
1024000 2731 1157803
1344000 3584 1519616
Peak Cell Rate
(cells per second)
ATM Bandwidth (bps)
(cell payload + overhead)
1
1. If a switch requires the A TM bandwidth equivalent of the PCR, use this equation: (peak
data rate*53 bytes per cell)/46.875 payload bytes per cell. For example, if peak data
rate is 512,000 bps: (512000*53)/46.875 = 578901 bps.
Promina Series
41
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Cellrate Calculations for VBR Circuits
Cellrate Calculations for VBR Circuits
This section describes how CellXpress converts Variable Bit Rate (VBR) to Peak Cell Rate (PCR).
Each VBR (Variable Bit Rate) Port Bundle has several parameters to control the traffic
management:
• PDR (Peak Data Rate)
• SDR (Sustainable Data Rate)
• MBT (Maximum Burst T olerance)
•Frame Size
• Cell Rate mode
The ATM traffic profile parameters that are used to program the AAL5 SAR device on the
CellXpress module are extracted from the above mentioned parameters. Unlike the CBR (Constant
Bit Rate) traffic profile which has a fixed ATM overhead per cell, the VBR traffic may have
substantial ATM overhead to convey the packet or frame. This is in addition to the normal five byte
cell header found in front of every cell. For information on the cellification process, see “Traffic
Shaping Overview” on page 29.
A significant factor in the amount of standard ATM overhead is the packet/frame size. Each packet/
frame must start at the beginning of a cell. Each succeeding cell is filled with the packet/frame
contents until the end of the packet/frame. This final cell in the set of cells used to convey the
packet/frame is filled with a ATM Forum compliant trailer fields to the end of this cell. If the
packet/frame ends in the first byte of the final cell, then the remaining 47 bytes are AT M overhead.
This is significant (approximately 50 percent) if the packet/frame is small (for example, 87 bytes),
but far less of a problem (approximately percent) if the packet/frame is large (for example, 1500
bytes). This is the way the cellification process works in the ATM environment.
Keep in mind that you should be checking the PCR value to see if you can place the call on your
back card type. A VBR Port Bundle with a PDR of 1024 Kbps can not be supported on T1 for
example. Adjust your SDR rate to match your expected average packet/frame data rate.
For GCRA Maximum a 1 Mbps call generates 4, 448 cells per second, which is greater than the
capacity of a T1. If you configure a sustained cellrate of 896 Kcps, you will (on average) receive a
cellrate that is greater than the span capacity, which results in the dropping of cells. Keep in mind
that you can configure the frame size and you may get a 1 Mbps call with a much lower PCR value.
Any change to the frame size or cellrate lowers the PCR value. Essentially increasing the frame size
rate and cellrate could allow the 1 Mbps call to be processed.
PDR refers to the (non-cell) packet/frame data rate from the PX-based application over the TBus.
VCCs on some ATM switches can also be configured in bps. This should be avoided
since it refers to the bits per second taken up on the ATM span by the entire 53 byte
cell. Use cells/second instead when dealing with cell traffic to avoid confusion by
your carrier operator.
42 ATM Modules
Page 63
SCLX Overview
This chapter provides an overview of the SCLX module and describes how it functions within the
Promina Series network. This chapter contains the following sections:
• “Description” in the next section
• “Features” on page 44
• “System Requirements” on page 45
• “SCLX Bundle Types” on page 45
• “SCLX Logical Span” on page 49
• “SCLX Physical Link” on page 49
• “Clock Reference Overview” on page 50
• “TBus Bandwidth Overview” on page 50
• “SCLP Overview” on page 50
• “Redundancy Overview” on page 51
• “Cellrate Calculations for CBR DVT Circuits” on page 52
• “Traffic Shaping Overview” on page 52
Chapter 3
Promina Series 43
Page 64
Description
Description
Features
The Promina SCLX can interoperate with ATM networks to increase traffic capacity to 64 Mbps
over direct virtual trunk bundles. The SCLX provides an intelligent, high-speed transport and
aggregation point for the Promina network, allowing access to broadband multi-service networks.
SCLX provides the following major features:
• ATM User-to-Network Interface (UNI) 3.1 support with or without LMI.
• Constant Bit Rate (CBR) Quality of Service (QoS) class.
• Conversion of CBR traffic to ATM cells using AAL1.
• CBR structured and unstructured mode.
• Different types of traffic multiplexed into a single ATM stream.
• SNMP support.
• Supports CBR Direct Virtual Trunk (DVT) bundles to approximately 32 Mbps.
• Supports CBR Port bundles to 8.192 Mbps.
• Supports VBR Port bundles to 8.192 Mbps.
• Supports up to 64 bundles per SX spigot for a total of 128 bundles. A maximum 96 can be
DVTs and the remainder may be CBR Port bundles. There may be other system constraints
that limit the number and size of bundles such as the number of other kinds of trunks
configured in the node.
• DVTs support all rate calls, including Nx64 Kbps.
• OAM performance monitoring on a DVT framing channel.
• OAM diagnostics support.
• SCLX to CellXpress internetworking (via a Single-mode or Multi-mode facility set to OC-3c
or STM-1 framing).
When interworking with CX is selected (see the Far End parameter), there are a
number of settings which are enforced as listed below:
1 Calls are limited to Nx64 Kbp s
2 Bundle sizes are limited to 2 Mbps.
3 Sync mode is set
On SCLX Direct Virtual Trunk bundles, the SCLP signaling channel can be set to
16 Kbps or 64 Kbps. Each PPM can not support more than 31 SCLX Direct Virtual
Trunks. As PPM resources are reserved for use by other trunks and/or tasks, a
number of PPMs may be required to support the total SCLX DVTs configured.
44 ATM Modules
Page 65
Feature Key
SCLX connection to third party ATM equipment is controlled by a Promina feature key. Unless
enabled, the SCLX module can only interoperate with SCREAM nodes that provide a special
“heartbeat” connection. To activate the feature key, note that it can enabled by any user without
assistance from the N.E.T. Technical Assistance Center (TAC). Any key will now be accepted to
enable or disable the feature.
System Requirements
The SCLX module can be installed in a High Speed Shelf (HSS-2) of a Promina node. The Promina
supports up to four non-redundant SCLX modules.
SCLX does not perform any local ATM switching. All traffic received from the ATM interfaces is
routed across the backplane to the appropriate Promina Series modules, and all traffic received
from Promina Series modules is routed to the appropriate ATM interface using the Virtual Path
Identifier (VPI) and the Virtual Channel Identifier (VCI).
SCLX Bundle Types
SCLX supports ATM access through the use of virtual objects called bundles. These bundles are
implemented via Permanent Virtual Circu its (PVCs). Switched Virtual Circuits (SVCs) are not
supported.
There are three types of SCLX bundles:
Description
• CBR Direct Virtual Trunk — a logical trunk that multiplexes Trunk Synchronous (TS) or
Trunk Asynchronous (TA) Promina circuits (requires Async mode) into one ATM Virtual
Channel Connection (VCC) without the need for a TRK3 module as an aggregator.
• CBR Port — A direct connection between an originating HSD-2B or other supported feature
module and a destination SCLX port (which is mapped to an ATM VCC). CBR Ports can be
configured to contain structured or unstructured ATM cell data.
• VBR Port — A direct connection between an originating HSD-2B or other supported feature
module and a destination SCLX port (which is mapped to an ATM VCC). VBR Ports are
used to transport HDLC-encoded packet traffic with a peak and sustained bandwidth traffic
characteristic.
The number of installed bundles (of any type) can not exceed 64 per SX spigot assigned to the
module or 128 bundles per module. Each type of bundle counts toward this limit. If there are 30
CBR DVT already installed on a spigot, then there will be maximum of 34 Port bundles that can be
added on the same spigot assuming other limitations such as bandwidth are available.
Due to general Promina trunk limitations, the CBR DVT bundles are limited to 96
per module. Although you can configure that many CBR DVT s on an SCLX, ther e is
a system limitation of 64 different neighbor nodes that can be configured, so some
of the links will have multiple trunks.
Promina Series
45
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Description
PRC
HSD-2B
CX
SCLX
Promina Series
VCC 1
VCC 2
Promina Series
VCC 1
VCC 2
ATM
Network
CBR Direct Virtual Trunk Bundles
CBR traffic from various Promina voice and data modules, such as the PRC or HSD-2B, can be
passed to an SCLX which multiplexes the calls into bundles. Each bundle is mapped to one ATM
VCC. An SCLP circuit is part of this bundle and no TRK-3 tandem-mode card is required for this
configuration. All calls can be supported (including non Nx64 Kbps) between neighbor SCLX
modules.
When interoperability with CellXpress is desired, the CBR DVT on the SCLX can be configured to
communicate with a neighbor CellXpress module.
When the CX interoperability mode is set (FAR END = CX), all of the bund le and
call size limitations on the CX apply to the SCLX.
See Chapter 1 Trunk Modules Overview of the Trunk Modules manual for a discussion of Trunk
processing and an overview of SCLP. SCLX supports up to 64 CBR Direct Virtual Trunk bundles
per SX spigot (or a total of any 128 bundles per module). See Figure 1 .
Figure 1 CBR Direct Virtual Trunk Bundles
46 ATM Modules
Page 67
Description
VCC
SCLX
PRC
ATM Network
Bundle
AAL1
Compliant
Device
CBR Port Bundles
A CBR port bundle provides an ATM access path for an originating data or voice port. The
origination port can be a PX-3, USD, HSD-2B, PRC, or TMCP module. The CBR traffic from the
Promina voice or data module is passed to SCLX, then mapped to a VCC for transport to an ATM
network.
Unlike CBR direct virtual trunk bundles, CBR port bundles do not use the SCLP. SCLX supports
up to 128 CBR port bundles. CBR port bundles can originate and terminate a call. Figure 2 shows
an example of a CBR port bundle application.
Figure 2 CBR Port Bundles
T ermination on the remote end of the ATM network can be a variety of third party ATM devices or
another SCLX or CellXpress-equipped Promina node. The SCLX conversion of CBR traffic data to
ATM cells uses an ATM Forum compliant AAL1 structured data method. Alternately, an
unstructured data method can be configured. The supported speeds are limited to Nx64 Kbps from
64 Kbps to 4 Mbps plus all HSD-2B supported speeds from 4 Mbps to 8 Mbps.
Note that the Synchronous Residual Time Stamp (SRTS) or adaptive timing
methods are not supported by SCLX. It is recommended that the Promina node be
synchronized to the same clock source as the remote ATM device.
Promina Series
47
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Description
VCC
SCLX
PX-3
ATM Network
Bundle
AAL5 1483
Compliant
Device
VBR Port Bundles
A VBR port bundle provides an ATM access path for an originating port on a data or packet module
conveying bit synchronous HDLC-encoded packet traffic. The origination port can be a PX-3,
USD, or HSD-2B module. The VBR traffic from the Promina data module is passed to SCLX, then
mapped to a (non-real-time) AAL5 VCC for transport to an ATM network.
Unlike CBR direct virtual trunk bundles, VBR port bundles do not use the SCLP. SCLX supports
up to 128 VBR port bundles. VBR port bundles can originate and terminate a call. Figure 3 shows
an example of a VBR port bundle application.
Figure 3 VBR Port Bundles
T ermination on the remote end of the ATM network can be a variety of third party ATM devices or
another SCLX or CellXpress-equipped Promina node. The SCLX conversion of CBR or VBR
traffic data to ATM cells uses an ATM Forum compliant AAL5 / RFC 1483 encoded data method.
The supported speeds are limited to Nx64 Kbps from 64 Kbps to 4 Mbps plus all HSD-2B
supported speeds from 4 Mbps to 8 Mbps.
Note that the Synchronous Residual Time Stamp (SRTS) or adaptive timing
methods are not supported by SCLX. It is recommended that the Promina node be
synchronized to the same clock source as the remote ATM device.
See Setting Up Reference Clock Sources on the Node in Chapter 3 Promina Clocking in the Node
Management manual for more information on setting node clock references.
Due to bandwidth reservations on the system bus, there is a small amount of
bandwidth on each SX spigot (224 Kbps) that can not be used by bundles. DVT
bundles can be allocated in this portion, but calls may fail to build if that reserved
space is needed. Port bundles will not be allocated in this space and will fail
initialization if that is the only space available. To increase the chance that Port
bundles are allocated in a non-reserved portion of the bus, it is recommended to
use lower bundle numbers for them.
48 ATM Modules
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SCLX Logical Span
12 3456
Reserved
Reserved
MIC 2 (not visible)
*Reserved
MFC 1
MIC 1 (not visible)
MIC 3(not visible)
PIM
PIM
PIM
PIM
1.2
2.2
1.1
2.1
MIC 4(not visible)
PIM
PIM
PIM
PIM
4.1
3.1
4.2
3.2
1
2
3
4
9
1
1
1
1
1
1
1
5
6
7
8
2
9
1
1
1
1
1
1
1
1
5
1
9
9
1
1
3
4
56
78
Blank Filler
Gig
U
O
O
D10
O
NDP 4
E
S
NDP 1
E
S
NDP 2
E
S
NDP 3
E
S
Promina 800 HSS-2 back view
SCREAM100 front view
OC-3c/
STM-1 MM
An SCLX Logical Span consists of 32 Mbps of bandwidth (corresponding to a Promina “shelf”)
which rides over the physical link between the SCLX interface and the ATM network. See “SCLX
Cabling to SX Spigots” on page 96.
SCLX consumes up to 64 Mbps from direct connections to an SX-2 module. For information on
connecting to an SX-2 module, see “Hardware Installation” on page 87. For more information on
the SX-2 module, see the P800 Installation and Maintenance manual.
SCLX Physical Link
The Physical Links, Primary and Secondary (PRI and SEC), are the physical links between the
SCLX and the ATM network. For example, cabling SCLX with SCREAM multi-mode OC-3c/
STM-1 ports as shown in Figure 4.
Figure 4 Logical Spans and Physical Link from Promina to SCREAM
Description
Each of the two SX connections (or logical spans) on the SCLX handles 32 Mbps.
Either one or both connections can be activated.
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Description
Clock Reference Overview
The primary (PRI) physical link on an SCLX can be used as a reference clock source to provide
clocking to the Promina network. If the span is not available, the card is not used as a reference
clock source.
The clock reference select parameter determines whether the card provides clocking. For more
information, see [ 1] Clock Reference Select on page 7-4.
For more information about the clock status of a node, see the Node Management manual.
TBus Bandwidth Overview
The Promina Series platform uses an internal bus called the TBus to transport data between cards in
a node. The TBus provides bandwidth across the backplane on each shelf. It is the medium for
carrying intranodal bandwidth; either a trunk or SCLX module are the medium for carrying
internodal bandwidth.
Bundle TBus Allocation
For SCLX, up to two logical spans of 32 Mbps each for a total of 64 Mbps of TBus bandwidth is
allocated to bundles on a bundle by bundle basis by the SCLX controlling task. The task can handle
any granularity of bundle bandwidth down to Nx16 Kbps. TBus allocation for any one bundle must
be entirely contained from within a single SX-2 spigot (logical span).
Setting the CBR DVT bundle mode to Async permits support for all types of calls on a Promina
node. It conveys the TBus valid bit in the ATM cell stream to support all these calls. Setting the
CBR DVT bundle mode to Sync eliminates the TBus valid bit from the ATM cell stream and the
user is limited as a result to Nx16K trunk synchronous calls.
SCLP Overview
The Signaling Channel Link Protocol (SCLP) is an internodal communications channel that is
present on all trunks and bundles, except port bundles. The SCLP carries messages that allows
users to configure, query, and monitor all nodes from anywhere in the network.
Call processing (building and tearing down calls) and SNMP are very taxing fun c tio ns pe rform ed
by the SCLP. If a trunk goes down, the SCLP carries numerous messages to reconnect calls, so all
calls traversing that trunk can be rerouted through the network over different trunks.
CBR Direct Virtual Trunk bundles on SCLX are capable of supporting a variable number of calls;
therefore, the bandwidth allocated to the SCLP channel is fixed at 64 Kbps. However, 16 Kbps is
available through a parameter setting. The more calls that are supported by the trunk, the more
important it is that the SCLP channel be large enough to build and tear down calls with acceptable
response times.
50 ATM Modules
Page 71
Redundancy Overview
For SCLX, domain and physical link level redundancy (PRI and SEC) is supported. See for
Figure 4 for cabling a redundant configuration.
Domain Redundancy
SCLX modules are connected to SX-2 modules. Redundancy is supported by cabling th e SXn-A
(where n = 0 or 1) ports on the SCLX rear interface card to spigots on A domain SX-2 modules and
cabling the corresponding SXn-B ports on the SCLX rear interface card to the same numbered
spigots on a B domain SX-2 module. For example, if SX0-A is connected to SX-2 spigot 7 on the A
domain, then SX0-B must also be connected to SX-2 spigot 7 on the B domain.
Description
The attached ATM device must support redundancy in order for SCLX link
redundancy to function.
For more information about the SX-2 module, see the P800 Installation and
Maintenance manual.
Link Redundancy
Up to two logical spans sharing the same physical OC-3c/STM-1 link can be used.
The second OC-3c/STM-1 link automatically comes on-line if the primary OC-3c/STM-1 link goes
down. The OC-3c/STM-1 redundant spans are not used for extra bandwidth.
SCLX 1:1 card redundancy is not supported.
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Traffic Shaping Overview
Traffic Shaping Overview
Traffic shaping is a mechanism that alters the traffic characteristics of a stream of cells while
meeting the QoS objectives, or to ensure conformance of a traffic configuration (or contract) at a
subsequent interface.
Cellrate Calculations for CBR DVT Circuits
This section describes the calculation (performed automatically by the system) of the size of an
ATM virtual circuit for an SCLX CBR Direct Virtual T runk bundle. The bandwidth of the bundle is
converted to the peak cell rate (PCR) with an associated cell delay variation (CDV).
Typically, it is the PCR, CDV, along with the VPI, VCI that is required when configuring a virtual
circuit on an ATM switch.
Query the bundle and use the PCR and CDV values on the destination ATM switch.
To determine the CDV
Use this equation to calculate the default CDV:
32768000/<bundle bandwidth> * 7 μsec = CDV
For example, if the bandwidth is 2048 Kbps:
32768000/2048000 * 7 = 112 μsec.
For bandwidth rates less than 512 Kbps, the CDV maximum will be 448
μsec and the minimum will be 30 μsec for 8.192 Mbps and above.
To determine the PCR
Table 1 lists the bandwidth and peak cell rates for all the bundle bandwidth settings of DVT
bundles in async mode. Table 2, which follows, lists the bandw idth and peak cell rates for all the
bundle bandwidth settings of DVT bundles in sync mode.
Table 1 Async Mode Bandwidth to PCR Conversions
Bandwidth (kbps) Peak Cell Rate (cps)
64 201
128 397
192 593
256 788
320 984
384 1180
448 1376
512 1571
576 1767
52 ATM Modules
Page 73
Traffic Shaping Overview
Table 1 Async Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
640 1963
704 2158
768 2354
832 2550
896 2746
960 2941
1024 3137
1088 3333
1152 3528
1216 3724
1280 3920
1344 4116
1408 4311
1472 4507
1536 4703
1600 4898
1664 5094
1728 5290
1792 5486
1856 5681
1920 5877
1984 6073
2048 6268
4096 12531
6144 18796
8192 25062
10240 31338
Promina Series
12288 37593
14336 43859
16384 50125
18432 56465
20480 62695
53
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Traffic Shaping Overview
Table 1 Async Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
22528 68965
24576 75187
26624 81566
28672 87719
30720 94073
32768 100401
Table 2 lists the bandwidth and typical peak cell rates for all the bundle bandwidth settings of DVT
bundles in sync mode:
Table 2 Sync Mode Bandwidth to PCR Conversions
Bandwidth (kbps) Peak Cell Rate (cps)
64 176
128 347
192 518
256 688
320 859
384 1030
448 1200
512 1371
576 1542
640 1712
704 1883
768 2054
832 2224
896 2395
960 2566
1024 2736
1088 2907
1152 3078
1216 3248
1280 3419
54 ATM Modules
Page 75
Traffic Shaping Overview
Table 2 Sync Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
1344 3590
1408 3760
1472 3931
1536 4102
1600 4272
1664 4443
1728 4614
1792 4784
1856 4955
1920 5126
1984 5296
2048 5467
4096 10928
6144 16393
8192 21857
10240 27322
12288 32786
14336 38240
16384 43744
18432 49188
20480 54644
22528 60132
24576 65573
26624 71123
28672 76569
30720 81967
32768 87489
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Traffic Shaping Overview
Cellrate Calculations for CBR Port Circuits
This section describes the calculated size of an ATM virtual circuit for an SCLX CBR Port bundle.
The bandwidth of the bundle is converted to the peak cell rate (PCR).
T ypically, it is the PCR that is required when configuring a virtual circuit on an ATM switch.
To determine the PCR
The setting of the Mode parameter affects the PCR calculation. Table 3 lists the bandwidth and
typical peak cell rates for bundles in structured mode. Table 4, which follows, lists the bandwidth
and typical peak cell rates for bundles in unstructured mode.
Table 3 Structured Mode Bandwidth to PCR Conversions
Bandwidth (kbps) Peak Cell Rate (cps)
64 176
128 347
192 518
256 688
320 859
384 1030
448 1200
512 1371
576 1542
640 1712
704 1883
768 2054
832 2224
896 2395
960 2566
1024 2736
1088 2907
1152 3078
1216 3248
1280 3419
1344 3590
1408 3760
1472 3931
56 ATM Modules
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Traffic Shaping Overview
Table 3 Structured Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
1536 4102
1600 4272
1664 4443
1728 4614
1792 4784
1856 4955
1920 5126
1984 5296
2048 5467
2112 5638
2176 5808
2240 5979
2304 6150
2368 6320
2432 6491
2496 6662
2560 6832
2624 7003
2688 7174
2752 7344
2816 7515
2880 7686
2944 7856
3008 8028
3072 8199
3136 8368
3200 8539
Promina Series
3264 8710
3328 8880
3392 9053
3456 9224
3520 9393
57
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Traffic Shaping Overview
Table 3 Structured Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
3584 9564
3648 9736
3712 9905
3776 10075
3840 10248
3904 10416
3968 10587
4032 10758
4096 10928
4160 11101
4224 11272
4288 11441
4352 11613
4416 11784
4480 11954
4544 12127
4608 12295
4672 12467
4736 12637
4800 12810
4864 12978
4928 13149
4992 13322
5056 13493
5120 13661
5184 13831
5248 14003
5312 14174
5376 14345
5440 14513
5504 14684
5568 14856
58 ATM Modules
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Traffic Shaping Overview
Table 3 Structured Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
5632 15026
5696 15197
5760 15370
5824 15540
5888 15710
5952 15883
6016 16051
6080 16220
6144 16393
6208 16567
6272 16736
6336 16906
6400 17076
6464 17247
6528 17418
6592 17590
6656 17758
6720 17934
6784 18099
6848 18271
6912 18446
6976 18611
7040 18779
7104 18953
7168 19120
7232 19301
7296 19470
Promina Series
7360 19642
7424 19809
7488 19980
7552 20149
7616 20321
59
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Traffic Shaping Overview
Table 3 Structured Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
7680 20491
7744 20661
7808 20833
7872 21003
7936 21172
8000 21344
8064 21514
8128 21687
8192 21857
Table 4 lists the bandwidth and typical peak cell rate s for bundl es in unstructured mode.
Table 4 Unstructured Mode Bandwidth to PCR Conversions
Bandwidth (kbps) Peak Cell Rate (cps)
64 176
128 346
192 516
256 686
320 857
384 1027
448 1197
512 1367
576 1537
640 1708
704 1878
768 2048
832 2218
896 2388
960 2559
1024 2729
1088 2899
1152 3069
1216 3240
60 ATM Modules
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Traffic Shaping Overview
Table 4 Unstructured Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
1280 3410
1344 3580
1408 3750
1472 3920
1536 4091
1600 4261
1664 4431
1728 4601
1792 4771
1856 4942
1920 5112
1984 5282
2048 5452
2112 5623
2176 5793
2240 5963
2304 6133
2368 6303
2432 6474
2496 6644
2560 6814
2624 6985
2688 7155
2752 7326
2816 7495
2880 7665
2944 7836
Promina Series
3008 8006
3072 8176
3136 8347
3200 8517
3264 8687
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Traffic Shaping Overview
Table 4 Unstructured Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
3328 8857
3392 9028
3456 9198
3520 9367
3584 9537
3648 9708
3712 9880
3776 10049
3840 10219
3904 10389
3968 10559
4032 10729
4096 10899
4160 11070
4224 11242
4288 11411
4352 11580
4416 11750
4480 11921
4544 12091
4608 12262
4672 12433
4736 12602
4800 12771
4864 12944
4928 13114
4992 13287
5056 13457
5120 13623
5184 13793
5248 13966
5312 14134
62 ATM Modules
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Traffic Shaping Overview
Table 4 Unstructured Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
5376 14306
5440 14480
5504 14649
5568 14814
5632 14990
5696 15160
5760 15325
5824 15501
5888 15671
5952 15835
6016 16010
6080 16181
6144 16350
6208 16520
6272 16691
6336 16860
6400 17032
6464 17202
6528 17373
6592 17540
6656 17711
6720 17885
6784 18050
6848 18221
6912 18395
6976 18566
7040 18733
Promina Series
7104 18903
7168 19073
7232 19245
7296 19417
7360 19584
63
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Traffic Shaping Overview
Table 4 Unstructured Mode Bandwidth to PCR Conversions (continued)
Bandwidth (kbps) Peak Cell Rate (cps)
7424 19758
7488 19920
7552 20096
7616 20263
7680 20437
7744 20605
7808 20777
7872 20942
7936 21119
8000 21294
8064 21459
8128 21630
8192 21805
Some of the Nx64 Kbps call speeds greater than 2 Mbps and less than 8 Mbps may not be
supported in your release. Check your release notes to determine which call speeds are supported.
When you configure the bundle bandwidth parameter in the OI, all the supported call speeds will be
listed.
If the OAM cell count is modified on the bundle configuration (from the default of
5), the resultant PCR will change slightly and may no longer be equal to the table’ s
value for that bandwidth. The Query Bundle display will indicate the new PCR
value after conversion. The amount that the PCR will change will be approximately
equal to the change in the OAM cell count.
64 ATM Modules
Page 85
Reassembly Buffer Calculations for CBR Circuits
The SCLX reassembly buffer specifies the size of the buffer on the SCLX module used for
reassembly of ATM cells. This buffer accommodates variances in the arrival of the ATM cells. In
most cases, the default is sufficient. For bundles that traverse a satellite link, the following formula
can be used to determine an appropriate reassembly buffer size.
(bundle bandwidth rate * delay variation) / 8) + 1024
where the delay variation is the amount of delay variation (in milliseconds) in the satellite link and
not the absolute delay. For example, suppose your bundle bandwidth is 2.048 Mbps and the delay
variation is 2 ms, then the calculation would be:
(2048 x 10e3 * 2x10e-3) / 8 + 1024 = 1536 bytes.
Specify this calculated value of 1536 as the reassembly buffer size for bundles going over this
satellite link. For non-satellite links, the buffer size of 1024 is sufficient.
The reassembly buffer is configurable from 48 to 48000 bytes.
Cellrate Calculations for VBR Port Circuits
This section describes the calculations of an ATM virtual circuit for an SCLX VBR Port bundle.
The peak bandwidth of the bundle is converted to the peak cell rate (PCR). The sustained
bandwidth of the bundle is converted to the sustained cell rate (SCR). Typically, it is the PCR and
SCR that is required when configuring an AAL5 (non-real-time) virtual circuit on an ATM switch.
Each VBR (Variable Bit Rate) Port Bundle has several parameters to control the traffic
management:
Traffic Shaping Overview
• PDR (Peak Bandwidth)
• SDR (Sustained Bandwidth)
• MBS (Maximum Burst Cells)
• Average Frame Size
• Cell Rate Mode
The ATM traffic profile parameters that are used to program the AAL5 SAR device on the SCLX
module are extracted from the above mentioned parameters. Unlike the CBR (Constant Bit Rate)
traffic profile which has a fixed ATM overhead per cell, the VBR traffic may have substantial ATM
overhead to convey the packet or frame. This is in addition to the normal five byte cell header
found in front of every cell. For information on the cellification process, see “Traffic Shaping
Overview” on page 52.
A significant factor in the amount of standard ATM overhead is the packet/frame size. Each packet/
frame must start at the beginning of a cell. Each succeeding cell is filled with the packet/frame
contents until the end of the packet/frame. This final cell in the set of cells used to convey the
packet/frame is filled with an ATM Forum compliant trailer field to the end of this cell. If the
packet/frame ends in the first byte of the final cell, then the remaining 47 bytes are AT M overhead.
This is significant (approximately 50 percent) if the packet/frame is small (for example, 87 bytes),
but far less of a problem (approximately percent) if the packet/frame is large (for example, 1500
bytes). This is the way the cellification process works in the ATM environment.
Keep in mind that you can configure the frame size and you may get your call with a much lower
PCR value. A change to the frame size or bandwidth may lower the PCR value. Essentially
increasing the frame size rate and cellrate could allow the 1 Mbps call to be processed.
Peak Bandwidth refers to the (non-cell) packet/frame data rate from the packet-based application
over the TBus.
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Traffic Shaping Overview
VCCs on some ATM switches can also be configured in bps. This should be avoided
since it refers to the bits per second taken up on the ATM span by the entire 53 byte
cell. Use cells/second instead when dealing with cell traffic to avoid confusion by
your carrier operator.
SCLX Compatibility Feature
A feature key is available to enable interoperability with ATM switches. If SCLX Compat is
enabled, SCLX is able to communicate with an A TM Forum standards based ATM device including
<N.E.T.>N.E.T.’s SCREAM platform. The feature key may be enabled by any user. Any key is
accepted. The default is disabled. When this is disabled, the SCLX can only communicate to a
<N.E.T .>N.E.T. SCREAM port that can provide the “heartbeat” the SCLX requires before traffic
can connect.
To query the current feature key status, see Example 1.
Example 1 SCLX Compat feature key
< quer feature
QUERY FEATURE on which NODE(S)? [THIS NODE]
NODE ID =
*** Node 33 (D123N33) Keyed Features ***
INTU_558 disabled
INTU_560 disabled
Native Agent enabled
Dual Agent disabled
SCLX Compat enabled
*** Command Complete ***
66 ATM Modules
Page 87
Hardware Description
This chapter describes the front and rear interface cards of the ATM modules, CellXpress and
SCLX, including information on the front panel components and rear panel connectors.
This chapter contains the following sections:
• “CellXpress Front Card” on page 69
• “CellXpress Interface Cards” on page 71
• “SCLX Front Card” on page 82
• “SCLX Interface Card” on page 84
Chapter 4
Promina Series 67
Page 88
Hardware Components
Hardware Components
The ATM modules consists of the following components:
• A front card containing the logic that controls the specific functions of an ATM module,
which include CellXpress and SCLX modules.
• A rear interface card that provides the physical connection between the node and external
trunk equipment.
Interface Modules
The CellXpress module supports the following interfaces:
• T1 with four external ports (see “T1 Interface Card” on page 71)
• E1 with four external ports, in balanced and unbalanced versions (see “E1 Interface Card” on
page 74)
• T3 with one external port (see “T3 Interface Card” on page 77)
• E3 with one external port (see “E3 Interface Card” on page 79)
• CXI-S for redundancy (see “CXI-S Interface Card” on page 80)
• OC-3c provides optical interface (see “OC-3/STM-1 Interface Card” on page 81)
The SCLX module supports the following interface:
Shelf Types
• OC-3c/STM-1 provides optical interface (see “OC-3c/STM-1 Interface Card” on page 84)
The ATM modules can be installed in the following Promina Series type nodes:
• The CX module can be installed in any standard or expansion shelf
• The SCLX module can only be installed in HSS shelf 0 of a Promina 800 using slots 2
through 13.
For information on physically installing an ATM module, see “Hardware Installation” on page 87.
68 ATM Modules
Page 89
CellXpress Front Card
The CellXpress front card supports these functions:
• CBR traffic
– Eight CBR internal ports (up to 32 bundles)
– Up to 32 DS0s per port supporting Nx64 Kbps
– Data rates up to 2.048 Mbps per port
– AAL1 segmentation and reassembly (SAR)
• VBR traffic
– Eight VBR internal ports (up to eight bundles)
– Data rates up to 4 Mbps per port
– Each port configurable for frame relay or HDLC
– Up to 16 VCCs per port for frame relay
– One VCC per port for HDLC
– AAL5 segmentation and reassembly (SAR)
• Up to 152 VCCs
• T1, E1, T3, E3, and OC-3c rear interface cards
CellXpress Front Card
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ASSY
CX
RED ALM
YEL ALM
DOWN
SYNC
LOOP
RST
+12V
+5V
-5V
GND
REV
IMA
HB
ONLINE
FAULT
CBUS
RED ALM
YEL ALM
DOWN
SYNC
LOOP
RED ALM
YEL ALM
DOWN
SYNC
LOOP
RED ALM
YEL ALM
DOWN
SYNC
LOOP
S
XXXXXX
P
A
N
3
S
P
A
N
2
S
P
A
N
1
S
P
A
N
0
LOOP LED (Yellow)
When lit, indicates that the span has been looped in or out.
DOWN LED (Yellow)
When lit, indicates that the corresponding ATM UNI is not
operating.
YELLOW ALARM LED (Yellow)
When lit, indicates that the corresponding ATM UNI detects a
remote alarm.
RED ALARM LED (Yellow)
When lit, indicates that the corresponding ATM User to Network
Interface (UNI) is experiencing a local alarm.
LEDs FOR SPANS 0-3
SYNC LED (Green)
When flashing, indicates that the corresponding ATM UNI is
achieving synchronization. When lit, indicates the corresponding
UNI is in sync.
RESET POSTS
Shorting these contacts resets the module.
VOLTAGE TEST POINTS (Red)
Used to check power supply voltages to the card.
GROUND TEST POINT (Black)
Provides a ground for voltage measurements.
CBUS LED (Yellow)
Lit when the card has CBus activity (implemented in hardware).
INVERSE MULTIPLEXING LED (Green)
When lit, indicates that the module is configured for Inverse Multiplexing
for ATM (IMA) mode.
Heart Beat LED (Green)
When blinking, indicates that the host processor on the card is
executing code.
ONLINE LED (Green)
Lit when the card is in online mode. Off when the card is in of fline mode.
FAULT LED (Yellow)
When lit, indicates a fault is detected on the card. Under control of the
card during powerup or a reset; under the control of the NC at other
times.
UART PORT CONNECTOR
A debug port providing a connection to a terminal.
A
CellXpress Front Card
CX Front Panel
Figure 1 describes the status indicators on the CX front panel.
Figure 1 CX Front Panel
70 ATM Modules
Page 91
CellXpress Interface Cards
CXI-T1
ASSY
Span 3
DB-15
Span 2
DB-15
Span 1
DB-15
Span 0
DB-15
T1 Interface Card
The T1 interface card supports up to four 1544 Kbps User to Network (UNI) physical layer (PHY)
interfaces. It supports the mapping of ATM cells based on ITU-T Recommendation G.804. The
DS1 signal operates
in ESF format and uses the B8ZS zero suppression method. Any span can be used as a nodal
reference clock source.
The card contains the Inverse Multiplexing for ATM (IMA) function and an ATM cell-to-clock/
data/frame format converter required by commercial T1 transceivers. The T1 interface is
configured through the Operator Interface. For information on the software parameters, see
“CellXpress Software Configuration” on page 101.
Figure 2 CXI-T1 Interface Card
CellXpress Interface Cards
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CellXpress Interface Cards
Onboard CSU
The CellXpress module has an integrated Channel Service Unit (CSU) for connection to the
network interface. The T1 interface card has an integrated Channel Service Unit.
(CSU) for connection to a DS-1 network interface.
Historically, a CSU is a service provider owned piece of equipment located on the customer
premises. The CSU has an interface towards the network (DS-1) and an interface towards the CPE
(DSX-1). The DSX-1 is a short haul interface. Network demarcation point was usually the DSX-1
interface. CSU has become a customer owned equipment and the network demarcation point is now
often on the DS-1 side.
Generic functions of a CSU include electrical isolation and protection, Line build out, layer 1
maintenance (alarms and loopback) and performance monitoring. The layer 1 maintenance and
performance monitoring function allow your service provider to monitor the quality of their
transmission facility and perform remote diagnostic if required. Different CSUs differ in the
amount of these maintenance and performance functions.
The CellXpress integrated CSU supports remote diagnostic loop control directed from the edge
node with standard in-band loop-up and loop-down commands on th e DS-1 span.
Certain service providers still prefer use of an external CSU on their own premises. In that
situation, an external CSU would be a possibility. However , verify if there is any interworking issue
when connecting the CellXpress (DS-1 electrical signal) to an input expecting a DSX-1 pulse.
Currently the CellXpress T1 interface module is not configurable directly to a DSX-1 electrical
signal, although appropriate settings of the LBO parameter will usually allow for successful
operation with this configuration.
If you do add an external CSU, the CellXpress spans may need to be manually reset from the
Promina Series operator console after use of in-band diagnostic loop commands by the service
provider if the CSU is left in a looped state. This may happen if the external CSUs forward the
loop-up command to the onboard CSU, but not the loop-down command.
72 ATM Modules
Page 93
CellXpress Interface Cards
Pinouts
The connector for the T1 interface card uses an adapter to convert the 15-pin female connector to a
15-pin male connector. Table 1 shows the pinouts for the DB-15 connector using the male adapter.
Table 1 CXI-T1 DB-15M (Male) Pinouts
Pin Signal Name Comment
1 TX_TIP_OUT Transmit tip From node
2 Not Used —
3 RX_TIP_IN Receive tip To node
4 Not Used —
5 Not Used
6 Not Used —
7 Not Used
8 Not Used —
9 TX_RING_OUT Transmit ring From node
10 Not Used —
11 RX_RING_IN Receive ring To node
12 Not Used
13 Not Used —
14 Not Used
15 Not Used —
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CellXpress Interface Cards
CXI-E1B
ASSY
Span 3
DB-15
Span 2
DB-15
Span 1
DB-15
Span 0
DB-15
E1 Interface Card
The E1 interface card supports up to four 2048 Kbps UNI PHY interfaces, based on ITU-T
Recommendation G.703 and G.704. It supports the mapping of ATM cells based on ITU-T
Recommendation G.804. The E1 signal supports the HDB3 zero-suppression method and can be
configured to use CRC-4. It requires an external channel service unit (CSU) for connection to the
network interface and it can be used as a nodal reference clock source.
The E1 interface card is available in a 120 ohm (balanced) version that uses DB-15 male
connectors, and a 75 ohm (unbalanced) version that uses BNC connectors.
The card contains the Inverse Multiplexing for ATM (IMA) function and an ATM cell-to-clock/
data/frame format converter required by commercial E1 transceivers. The E1 interface is
configured through the Operator Interface. For information on the software parameters, see
“CellXpress Software Configuration” on page 101.
Figure 3 CXI-E1B (Balanced) Interface Card
74 ATM Modules
Page 95
CellXpress Interface Cards
Backplane
TX
Connector
E1
RX
TX
RX
TX
RX
TX
RX
Span 3
Span 2
Span 1
Span 0
E1
BNC Connectors
E2
E5
E4
E3
E6
E7
E8
E2 ... E8
E1B Pinouts
The connector for the balanced version of the E1 interface card is a 15-pin male DSUB connector
identical to the one used for the T1 interface card. For a description of the pinouts, see “CXI-T1
DB-15M (Male) Pinouts” on page 73.
Figure 4 CXI-E1U (Unbalanced) Interface Card
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Page 96
CellXpress Interface Cards
E1U Jumper Settings
The unbalanced version of the E1 interface card contains jumpers for setting the ground reference.
As shown in Figure 4, the jumper for each physical span is located directly under the corresponding
connector for both transmit and receive. Table 2 describes the jumper settings.
Table 2 CXI-E1U (Unbalanced) Jumper Settings
Jumper Function Position
E1, E3, E5, E7 Chassis ground connected to receive coax
shield.
Receive coax shield floating. Pins uncovered
E2, E4, E6, E8 Chassis ground connected to transmit
coax shield.
Transmit coax shield floating. Pins uncovered
Pins covered
Pins covered
76 ATM Modules
Page 97
T3 Interface Card
CXI-T3
ASSY
SX-B
SX-A
Crypto
Re-Sync
TX
(out)
RX
(in)
DB 9
The T3 interface card supports a single isochronous (44.736 Mbps) DS3 C-bit parity UNI, using the
(frame format) Physical Layer Convergence Protocol (PLCP). It supports zero-suppression using
the B3ZS method. It also includes a crypto resync connector to support encryption equipment. The
T3 span can be used as a nodal reference clock source. PLCP defines the mapping of ATM cells
onto existing DS-3 facilities.
Two SX ports on the T3 card can provide an additional 32 Mbps of bandwid th to supplem e nt th e
TBus bandwidth supplied from the backplane. This direct SX-2 spigot connection is available in a
Promina 800 system. For information about connecting to SX-2 cards, see the P800 Installation
and Maintenance manual. For more information about the SX-2 module, see the P800 Installati on
and Maintenance manual. The IMA function is not supported on the CellXpress T3 mod ule.
The T3 interface is configured through the Operator Interface. For information on the software
parameters, see “Hardware Installation” on page 87.
Figure 5 CXI-T3 Interface Card
CellXpress Interface Cards
Promina Series
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CellXpress Interface Cards
Crypto Resync Connector
The crypto resync connector on the T3 interface card is a nine-pin D connector.
This connector provides a pulse train to the encryption device when the UNI chip indicates a Loss
of Frame (LOF). The pulse period is configurable through the Operator Interface.
The pinouts for the connector are shown in Table 3.
Table 3 CXI-T3 Crypto Re-Sync DB-9 Pinouts
Pin Signal Name Comment
1 SHLD GND Shield Ground —
2 CRYPTO(-) Crypto sync From node
3Not Used
4Not Used
5Not Used
6 CRYPTO(+) Crypto sync From node
7Not Used
8Not Used
9Not Used
Crypto Sync/Auxiliary Alarm Cabling
Cabling crypto sync/auxiliary alarm in a redundant configuration requires a Y-cable assembly. For
more information about crypto sync/auxiliary alarm cabling. The Y-cable configuration varies
according to site requirements and is not supplied by N.E.T..
78 ATM Modules
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E3 Interface Card
CXI-E3
ASSY
SX-B
SX-A
TX
(out)
RX
(in)
The E3 interface card supports a single asynchronous 34.368 Mbps G.832(plesiochronous digital
hierarchy) frame format, using the HDB3 zero-suppression method. The E3 module generates a
cell transport frame format, called Plesiochronous Digital Hierarchy (PDH). The PDH frame will
be synchronous to, but not aligned with, the E3 frame.The span can be used as a nodal reference
clock source.
T wo SX ports on the E3 card can provide additional bandwidth to supplement the TBus bandwidth
supplied from the backplane. For information about connecting to SX-2 cards, see the P800
Installation and Maintenance manual. For more information about the SX-2 module, see the P800
Installation and Maintenance manual. The E3 interface is configured through the Operator
Interface. For information on the software parameters, see “CellXpress Software Configuration” on
page 101.
The IMA function is not supported on the CellXpress E3 module.
Figure 6 CXI-E3 Interface Card
CellXpress Interface Cards
Promina Series
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CellXpress Interface Cards
CXI-S
ASSY
A
TX Main
B
A
RX Main
B
CXI-S Interface Card
The CellXpress T3 and E3 modules require a splitter card (CXI-S) for redundancy (this feature is
planned for a future release). The CXI-S card is installed in any empty rear card slot, on the same
shelf as the CellXpress module or on any adjacent shelf. The CXI-S card does not attach to the
backplane and is therefore not accessible through the Cbus.
Figure 7 shows the CXI-S card.
Figure 7 Splitter Card (CXI-S)
80 ATM Modules
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