Alcatel-Lucent OMNISWITCH 8800, OMNISWITCH-7700, OMNISWITCH-7800 Configuration Guide

Part No. 060161-10, Rev. J April 2006

OmniSwitch 7700/7800

OmniSwitch 8800

Advanced Routing

Configuration Guide

www.alcatel.com

This user guide documents release 5.4 of the OmniSwitch 7700, 7800, and 8800.

The functionality described in this guide is subject to change without notice.

Alcatel and Alcatel OmniVista

and the Alcatel logo are registered trademarks of Alcatel. Xylan®, OmniSwitch®, OmniStack®,

are registered trademarks of Alcatel Internetworking, Inc.

OmniAccess™, Omni Switch/Router™, PolicyView™, RouterView™, SwitchManager™, VoiceView™, WebView™, X-Cell™, X-Vision™, and the Xylan logo are trademarks of Alcatel Internetworking, Inc.

This OmniSwitch product contains components which may be covered by one or more of the following U.S. Patents:

• U.S. Patent No. 6,339,830

• U.S. Patent No. 6,070,243

• U.S. Patent No. 6,061,368

• U.S. Patent No. 5,394,402

• U.S. Patent No. 6,047,024

• U.S. Patent No. 6,314,106

• U.S. Patent No. 6,542,507

• U.S. Patent No. 6,874,090

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ii OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006

About This Guide .......................................................................................................... ix

Supported Platforms .......................................................................................................... ix

Who Should Read this Manual? ........................................................................................ xi

When Should I Read this Manual? ....................................................................................xi

What is in this Manual? ..................................................................................................... xi

What is Not in this Manual? ..............................................................................................xi

How is the Information Organized? .................................................................................xii

Documentation Roadmap ................................................................................................. xii

Related Documentation ...................................................................................................xiv

User Manuals Web Site .................................................................................................... xv

Technical Support ............................................................................................................ xv

Chapter 1 Configuring OSPF .......................................................................................................1-1

In This Chapter ................................................................................................................1-1

OSPF Specifications ........................................................................................................1-2

OSPF Defaults Table .......................................................................................................1-3

OSPF Quick Steps ...........................................................................................................1-4

OSPF Overview ..............................................................................................................1-7

OSPF Areas ..............................................................................................................1-8

Classification of Routers ..........................................................................................1-9

Virtual Links ............................................................................................................1-9

Stub Areas ..............................................................................................................1-10

Not-So-Stubby-Areas ......................................................................................1-11

Totally Stubby Areas .......................................................................................1-11

Equal Cost Multi-Path (ECMP) Routing ...............................................................1-12

Non-Broadcast OSPF Routing ...............................................................................1-12

Graceful Restart on Switches with Redundant CMMs ..........................................1-13

Configuring OSPF .........................................................................................................1-14

Preparing the Network for OSPF ...........................................................................1-15

Activating OSPF ....................................................................................................1-16

Creating an OSPF Area ..........................................................................................1-17

Creating OSPF Interfaces .......................................................................................1-21

Creating Virtual Links ............................................................................................1-24

Creating Redistribution Policies and Filters ...........................................................1-25

Configuring Router Capabilities ............................................................................1-28

Configuring Static Neighbors .................................................................................1-29

Configuring Redundant CMMs for Graceful Restart .............................................1-30

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 iii

Contents

OSPF Application Example ..........................................................................................1-31

Step 1: Prepare the Routers .............................................................................1-32

Step 2: Enable OSPF .......................................................................................1-34

Step 3: Create and Enable the Areas and Backbone ........................................1-34

Step 4: Create, Enable, and Assign Interfaces .................................................1-35

Step 5: Examine the Network ..........................................................................1-37

Verifying OSPF Configuration .....................................................................................1-38

Chapter 2 Configuring BGP .........................................................................................................2-1

In This Chapter .........................................................................................................2-1

BGP Specifications .........................................................................................................2-2

Quick Steps for Using BGP ............................................................................................2-3

BGP Overview ................................................................................................................2-4

Autonomous Systems (ASs) .....................................................................................2-5

Internal vs. External BGP .........................................................................................2-6

Communities ............................................................................................................2-7

Route Reflectors .......................................................................................................2-8

BGP Confederations .................................................................................................2-9

Policies ...................................................................................................................2-10

Regular Expressions ........................................................................................2-11

The Route Selection Process ..................................................................................2-14

Route Dampening ...................................................................................................2-15

CIDR Route Notation .............................................................................................2-15

BGP Configuration Overview .......................................................................................2-16

Starting BGP .................................................................................................................2-17

Disabling BGP ........................................................................................................2-17

Setting Global BGP Parameters ....................................................................................2-18

Setting the Router AS Number ...............................................................................2-19

Setting the Default Local Preference .....................................................................2-19

Enabling AS Path Comparison ...............................................................................2-20

Controlling the use of MED Values .......................................................................2-21

Synchronizing BGP and IGP Routes .....................................................................2-22

Displaying Global BGP Parameters .......................................................................2-23

Configuring a BGP Peer ................................................................................................2-24

Creating a Peer .......................................................................................................2-26

Restarting a Peer .....................................................................................................2-27

Setting the Peer Auto Restart .................................................................................2-27

Changing a Peer Address to the Local Router Address .........................................2-28

Clearing Statistics for a Peer ..................................................................................2-28

Setting Peer Authentication ....................................................................................2-29

Setting the Peer Route Advertisement Interval ......................................................2-29

Configuring a BGP Peer with the Loopback0 Interface ..................................2-29

Configuring Aggregate Routes .....................................................................................2-30

iv OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006

Contents

Configuring Local Routes (Networks) ..........................................................................2-31

Adding the Network ........................................................................................2-31

Configuring Network Parameters ....................................................................2-32

Viewing Network Settings ..............................................................................2-33

Controlling Route Flapping Through Route Dampening ..............................................2-34

Example: Flapping Route Suppressed, then Unsuppressed ............................2-34

Enabling Route Dampening ............................................................................2-35

Configuring Dampening Parameters ...............................................................2-35

Clearing the History ........................................................................................2-37

Displaying Dampening Settings and Statistics ................................................2-37

Setting Up Route Reflection .........................................................................................2-38

Configuring Route Reflection ................................................................................2-40

Redundant Route Reflectors ...................................................................................2-40

Working with Communities ..........................................................................................2-41

Creating a Confederation ..............................................................................................2-42

Routing Policies ............................................................................................................2-43

Creating a Policy ....................................................................................................2-43

Assigning a Policy to a Peer ...................................................................................2-48

Displaying Policies .................................................................................................2-50

Configuring Redistribution Filters ................................................................................2-51

Application Example .....................................................................................................2-53

AS 100 .............................................................................................................2-53

AS 200 .............................................................................................................2-54

Displaying BGP Settings and Statistics ........................................................................2-56

Chapter 3 Configuring Multicast Address Boundaries ........................................................3-1

In This Chapter ................................................................................................................3-1

Multicast Boundary Specifications .................................................................................3-2

Quick Steps for Configuring Multicast Address Boundaries ..........................................3-2

Using Existing Router Ports ..............................................................................3-2

On New Router Ports .........................................................................................3-2

Multicast Address Boundaries Overview ........................................................................3-4

Multicast Addresses and the IANA ..........................................................................3-4

Administratively Scoped Multicast Addresses ..................................................3-4

Source-Specific Multicast Addresses ................................................................3-4

Multicast Address Boundaries .................................................................................3-5

Concurrent Multicast Addresses ..............................................................................3-6

Configuring Multicast Address Boundaries ....................................................................3-7

Basic Multicast Address Boundary Configuration ...................................................3-7

Creating a Multicast Address Boundary ..................................................................3-7

Deleting a Multicast Address Boundary ..................................................................3-7

Verifying the Multicast Address Boundary Configuration .............................................3-7

Application Example for Configuring Multicast Address Boundaries ...........................3-8

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 v

Contents

Chapter 4 Configuring DVMRP ...................................................................................................4-1

In This Chapter ................................................................................................................4-1

DVMRP Specifications ...................................................................................................4-2

DVMRP Defaults ............................................................................................................4-2

Quick Steps for Configuring DVMRP ............................................................................4-3

DVMRP Overview ..........................................................................................................4-5

Reverse Path Multicasting ........................................................................................4-5

Neighbor Discovery .................................................................................................4-6

Multicast Source Location, Route Report Messages, and Metrics ..........................4-7

Dependent Downstream Routers and Poison Reverse .............................................4-7

Pruning Multicast Traffic Delivery ..........................................................................4-8

Grafting Branches Back onto the Multicast Delivery Tree ......................................4-8

DVMRP Tunnels ......................................................................................................4-9

Configuring DVMRP ....................................................................................................4-10

Enabling DVMRP on the Switch ...........................................................................4-10

Loading DVMRP into Memory .......................................................................4-10

Enabling DVMRP on a Specific Interface ......................................................4-11

Viewing DVMRP Status and Parameters for a Specific Interface ..................4-12

Globally Enabling DVMRP on the Switch .....................................................4-12

Checking the Current Global DVMRP Status .................................................4-12

Automatic Loading and Enabling of DVMRP Following a System Boot ......4-13

Neighbor Communications ....................................................................................4-13

Routes .....................................................................................................................4-14

Pruning ...................................................................................................................4-15

More About Prunes ..........................................................................................4-15

Grafting ..................................................................................................................4-17

Tunnels ...................................................................................................................4-17

Verifying the DVMRP Configuration ...........................................................................4-19

Chapter 5 Configuring PIM-SM ..................................................................................................5-1

In This Chapter ................................................................................................................5-1

PIM-SM Specifications ...................................................................................................5-2

PIM-SM Defaults ............................................................................................................5-3

Quick Steps for Configuring PIM-SM ............................................................................5-4

PIM-SM Overview ..........................................................................................................5-5

Rendezvous Points (RPs) .........................................................................................5-5

Candidate Rendezvous Points (C-RPs) .............................................................5-5

Bootstrap Routers (BSRs) ........................................................................................5-6

Candidate Bootstrap Routers (C-BSRs) ............................................................5-6

Designated Routers (DRs) ........................................................................................5-6

Shared (or RP) Trees .......................................................................................................5-7

Avoiding Register Encapsulation ....................................................................................5-9

RP Initiation of (S, G) Source-Specific Join Message .............................................5-9

SPT Switchover ......................................................................................................5-11

vi OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006

Contents

Configuring PIM-SM ....................................................................................................5-14

Enabling PIM-SM on the Switch ...........................................................................5-14

Verifying the Software ....................................................................................5-14

Loading PIM-SM into Memory .......................................................................5-15

Enabling IPMS ................................................................................................5-15

Enabling PIM-SM on a Specific Interface ......................................................5-16

Viewing PIM-SM Status and Parameters for a Specific Interface ..................5-16

Globally Enabling PIM-SM on the Switch .....................................................5-16

Checking the Current Global PIM-SM Status .................................................5-17

Automatic Loading and Enabling of PIM-SM Following a System Boot ......5-17

PIM Bootstrap and RP Discovery ..........................................................................5-18

Configuring a C-RP on an Interface .......................................................................5-18

Specifying a Multicast Group ..........................................................................5-18

Specifying the Maximum Number of RPs .............................................................5-19

Configuring Candidate Bootstrap Routers (C-BSRs) ............................................5-21

Candidate Bootstrap Routers (C-BSRs) ..........................................................5-21

Configuring a C-BSR on an Interface .............................................................5-21

Verifying your Changes .........................................................................................5-22

Bootstrap Routers (BSRs) ......................................................................................5-23

Configuring Static RP Groups ................................................................................5-23

Group-to-RP Mapping ............................................................................................5-24

Verifying the PIM-SM Configuration ...........................................................................5-25

PIM-SSM Support .........................................................................................................5-26

Source-Specific Multicast Addresses .....................................................................5-26

PIM-SSM Specifications ........................................................................................5-26

Appendix A Software License and Copyright Statements .....................................................A-1

Alcatel License Agreement ............................................................................................A-1

ALCATEL INTERNETWORKING, INC. (“AII”)

SOFTWARE LICENSE AGREEMENT ................................................................A-1

Third Party Licenses and Notices ..................................................................................A-4

A. Booting and Debugging Non-Proprietary Software ..........................................A-4

B. The OpenLDAP Public License: Version 2.4, 8 December 2000 .....................A-4

C. Linux ..................................................................................................................A-5

D. GNU GENERAL PUBLIC LICENSE: Version 2, June 1991 ..........................A-5

E. University of California ...................................................................................A-10

F. Carnegie-Mellon University ............................................................................A-10

G. Random.c .........................................................................................................A-10

H. Apptitude, Inc. .................................................................................................A-11

I. Agranat .............................................................................................................A-11

J. RSA Security Inc. ............................................................................................A-11

K. Sun Microsystems, Inc. ....................................................................................A-11

L. Wind River Systems, Inc. ................................................................................A-12

M. Network Time Protocol Version 4 ...................................................................A-12

Index ...................................................................................................................... Index-1

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 vii

Contents

viii OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006

About This Guide

This OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide describes how to set up and monitor advanced routing protocols for operation in a live network environment. The routing protocols described in this manual are purchased as an add-on package to the base switch software.

Supported Platforms

This information in this guide applies to the following products:

• OmniSwitch 7700

• OmniSwitch 7800

• OmniSwitch 8800

The OmniSwitch 7700 includes 10 slots for high performance 10/100 Ethernet and Gigabit Ethernet Network Interface (NI) modules. The OmniSwitch 7800 includes 18 slots for high performance 10/100 Ethernet and Gigabit Ethernet NI modules. The OmniSwitch 8800 includes 18 slots for high performance 10/100 Ethernet and Gigabit Ethernet NI modules.

Unsupported Platforms

The information in this guide does not apply to the following products:

• OmniSwitch (original version with no numeric model name)

• OmniSwitch 6624

• OmniSwitch 6648

• OmniSwitch 6600-U24

• OmniSwitch 6600-P24

• OmniSwitch 6602-24

• OmniSwitch 6602-48

• OmniSwitch 6800-24

• OmniSwitch 6800-48

• OmniSwitch 6800-U24

• OmniSwitch 6800-24L

• OmniSwitch 6800-48L

• OmniSwitch 6850

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 page ix

Supported Platforms About This Guide

• OmniSwitch 9700

• Omni Switch/Router

• OmniStack

• OmniAccess

page x OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006

About This Guide Who Should Read this Manual?

Who Should Read this Manual?

The audience for this user guide are network administrators and IT support personnel who need to configure, maintain, and monitor switches and routers in a live network. However, anyone wishing to gain knowledge on how advanced routing software features are implemented in the OmniSwitch 7700, 7800, 8800 will benefit from the material in this configuration guide.

When Should I Read this Manual?

Read this guide as soon as you are ready to integrate your OmniSwitch into your network and you are ready to set up advanced routing protocols. You should already be familiar with the basics of managing a single OmniSwitch as described in the OmniSwitch 7700/7800/8800 Switch Management Guide.

The topics and procedures in this manual assume an understanding of the OmniSwitch directory structure and basic switch administration commands and procedures. This manual will help you set up your switches to route on the network using routing protocols, such as OSPF.

What is in this Manual?

This configuration guide includes information about configuring the following features:

• Open Shortest Path First (OSPF) protocol

• Border Gateway Protocol (BGP)

• Multicast routing boundaries

• Distance Vector Multicast Routing Protocol (DVMRP)

• Protocol-Independent Multicast, Sparse Mode (PIM-SM) protocol

What is Not in this Manual?

The configuration procedures in this manual use Command Line Interface (CLI) commands in all examples. CLI commands are text-based commands used to manage the switch through serial (console port) connections or via Telnet sessions. Procedures for other switch management methods, such as web-based (WebView or OmniVista) or SNMP, are outside the scope of this guide.

For information on WebView and SNMP switch management methods consult the OmniSwitch 7700/ 7800/8800 Switch Management Guide. Information on using WebView and OmniVista can be found in the context-sensitive on-line help available with those network management applications.

This guide provides overview material on software features, how-to procedures, and application examples that will enable you to begin configuring your OmniSwitch. It is not intended as a comprehensive reference to all CLI commands available in the OmniSwitch. For such a reference to all OmniSwitch 7700/ 7800/8800 CLI commands, consult the OmniSwitch CLI Reference Guide.

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 page xi

How is the Information Organized? About This Guide

How is the Information Organized?

Chapters in this guide are broken down by software feature. The titles of each chapter include protocol or feature names (e.g., OSPF, PIM-SM) with which most network professionals will be familiar.

Each software feature chapter includes sections that will satisfy the information requirements of casual readers, rushed readers, serious detail-oriented readers, advanced users, and beginning users.

Quick Information. Most chapters include a specifications table that lists RFCs and IEEE specifications supported by the software feature. In addition, this table includes other pertinent information such as minimum and maximum values and sub-feature support. Most chapters also include a defaults table that lists the default values for important parameters along with the CLI command used to configure the parameter. Many chapters include a Quick Steps section, which is a procedure covering the basic steps required to get a software feature up and running.

In-Depth Information. All chapters include overview sections on the software feature as well as on selected topics of that software feature. Topical sections may often lead into procedure sections that describe how to configure the feature just described. Serious readers and advanced users will also find the many application examples, located near the end of chapters, helpful. Application examples include diagrams of real networks and then provide solutions using the CLI to configure a particular feature, or more than one feature, within the illustrated network.

Documentation Roadmap

The OmniSwitch user documentation suite was designed to supply you with information at several critical junctures of the configuration process. The following section outlines a roadmap of the manuals that will help you at each stage of the configuration process. Under each stage, we point you to the manual or manuals that will be most helpful to you.

Stage 1: Using the Switch for the First Time

Pertinent Documentation: OmniSwitch 7700/7800 Getting Started Guide

OmniSwitch 8800 Getting Started Guide Release Notes

A hard-copy OmniSwitch 7700/7800 Getting Started Guide is included with OmniSwitch 7700/7800 switches and a hard-copy OmniSwitch 8800 Getting Started Guide is included with OmniSwitch 8800 switches; these guides provide all the information you need to get your switch up and running the first time. These guides provide information on unpacking the switch, rack mounting the switch, installing NI modules, unlocking access control, setting the switch’s IP address, and setting up a password. They also include succinct overview information on fundamental aspects of the switch, such as hardware LEDs, the software directory structure, CLI conventions, and web-based management.

At this time you should also familiarize yourself with the Release Notes that accompanied your switch. This document includes important information on feature limitations that are not included in other user guides.

page xii OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006

About This Guide Documentation Roadmap

Stage 2: Gaining Familiarity with Basic Switch Functions

Pertinent Documentation: OmniSwitch 7700/7800 Hardware Users Guide

OmniSwitch 8800 Hardware Users Guide OmniSwitch 7700/7800 Switch Management Guide

Once you have your switch up and running, you will want to begin investigating basic aspects of its hard ware and software. Information about OmniSwitch 7700/7800 hardware is provided in the OmniSwitch

7700/7800 Hardware Users Guide. Information about OmniSwitch 8800 hardware is provided in the OmniSwitch 8800 Hardware Users Guide. These guides provide specifications, illustrations, and descrip-

tions of all hardware components—chassis, power supplies, Chassis Management Modules (CMMs), Network Interface (NI) modules, and cooling fans. They also include steps for common procedures, such as removing and installing switch components.

The OmniSwitch 7700/7800/8800 Switch Management Guide is the primary user guide for the basic software features on a single switch. This guide contains information on the switch directory structure, basic file and directory utilities, switch access security, SNMP, and web-based management. It is recommended that you read this guide before connecting your switch to the network.

Stage 3: Integrating the Switch Into a Network

Pertinent Documentation: OmniSwitch 7700/7800/8800 Network Configuration Guide

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide

When you are ready to connect your switch to the network, you will need to learn how the OmniSwitch implements fundamental software features, such as 802.1Q, VLANs, Spanning Tree, and network routing protocols. The OmniSwitch 7700/7800/8800 Network Configuration Guide contains overview information, procedures, and examples on how standard networking technologies are configured in the OmniSwitch 7700, 7800, and 8800.

The OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide includes configuration information for networks using advanced routing technologies (OSPF and BGP) and multicast routing protocols (DVMRP and PIM-SM).

Anytime

The OmniSwitch CLI Reference Guide contains comprehensive information on all CLI commands supported by the switch. This guide includes syntax, default, usage, example, related CLI command, and CLI-to-MIB variable mapping information for all CLI commands supported by the switch. This guide can be consulted anytime during the configuration process to find detailed and specific information on each CLI command.

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 page xiii

User Manuals Web Site

All related user guides for the OmniSwitch 7700, 7800, and 8800 can be found on our web site at http://www.alcatel.com/enterprise/en/resource_library/user_manuals.html

All documentation on the User Manual web site is in program for viewing. Acrobat Reader freeware is available at www.adobe.com.

Note. When printing pages from the documentation PDFs, de-select Fit to Page if it is selected in your print dialog. Otherwise pages may print with slightly smaller margins.

PDF format and requires the Adobe Acrobat Reader

Technical Support

An Alcatel service agreement brings your company the assurance of 7x24 no-excuses technical support. You’ll also receive regular software updates to maintain and maximize your Alcatel product’s features and functionality and on-site hardware replacement through our global network of highly qualified service delivery partners. Additionally, with 24-hour-a-day access to Alcatel’s Service and Support web page, you’ll be able to view and update any case (open or closed) that you have reported to Alcatel’s technical support, open a new case or access helpful release notes, technical bulletins, and manuals. For more information on Alcatel’s Service Programs, see our web page at eservice.ind.alcatel.com, call us at 1-800-9952696, or email us at support@ind.alcatel.com.

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 page xv

Technical Support About This Guide

page xvi OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006

1 Configuring OSPF

The Open Shortest Path First routing (OSPF) is the shortest path first (SPF), or link state, protocol. OSPF is an interior gateway protocol (IGP) that distributes routing information between routers in a single Autonomous System (AS). OSPF chooses the least-cost path as the best path. OSPF is suitable for complex networks with large numbers of routers since it provides faster convergence where multiple flows to a single destination can be forwarded on one or more interfaces simultaneously.

In This Chapter

This chapter describes the basic components of OSPF and how to configure them through the Command Line Interface (CLI). CLI commands are used in the configuration examples; for more details about the syntax of commands, see the OmniSwitch CLI Reference Guide.

Configuration procedures described in this chapter include:

• Loading and enabling OSPF. See “Activating OSPF” on page 1-16.

• Creating OSPF areas. See “Creating an Area” on page 1-17.

• Creating OSPF interfaces. See “Creating OSPF Interfaces” on page 1-21.

• Creating virtual links. See “Creating Virtual Links” on page 1-24

• Using redistribution policies and filters. See “Enabling Redistribution” on page 1-25

For information on creating and managing VLANs, see “Configuring VLANs” in the OmniSwitch 7700/ 7800/8800 Network Configuration Guide.

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 page 1-1

OSPF Specifications Configuring OSPF

OSPF Specifications

RFCs Supported 1370—Applicability Statement for OSPF

1850—OSPF Version 2 Management Information Base 2328—OSPF Version 2 2370—The OSPF Opaque LSA Option 3101—The OSPF Not-So-Stubby Area (NSSA) Option 3623 — Graceful OSPF Restart

Maximum number of Areas (per router) 10

Maximum number of Interfaces (per router) 70

Maximum number of Link State Database entries (per router)

Maximum number of adjacencies (per router)

Maximum number of ECMP gateways (per destination)

Maximum number of neighbors (per router) 64

Maximum number of routes (per router) 40000 (Depending on the number of interfaces/

50000

neighbors, this value may vary.)

page 1-2 OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006

Configuring OSPF OSPF Defaults Table

OSPF Defaults Table

The following table shows the default settings of the configurable OSPF parameters.

Parameter Description Command Default Value/Comments

Enables OSPF.

Enables an area.

Enables an interface.

Enables OSPF redistribution. ip ospf redist status disabled

Sets the overflow interval value.

Assigns a limit to the number of External Link-State Database (LSDB) entries.

Configures timers for Shortest Path First (SPF) calculation.

Creates or deletes an area default metric.

Configures OSPF interface dead interval.

Configures OSPF interface hello interval.

ip ospf status disabled

ip ospf area status disabled

ip ospf interface status disabled

ip ospf exit-overflow-interval 0

ip ospf extlsdb-limit -1

ip ospf spf-timer delay: 5

hold: 10

ip ospf area default-metric ToS: 0

Type: OSPF Cost: 1

ip ospf interface dead-interval 40 seconds (broadcast and

point-to-point) 120 seconds (NBMA and point-to-multipoint)

ip ospf interface hello-interval 10 seconds (broadcast and

point-to-point) 30 seconds (NBMA and pointto-multipoint)

Configures the OSPF interface cost. ip ospf interface cost 1

Configures the OSPF poll interval. ip ospf interface poll-interval 120 seconds

Configures the OSPF interface priority.

Configures OSPF interface retransmit interval.

Configures the OSPF interface transit delay.

Configures the OSPF interface type. ip ospf interface type broadcast

Configures graceful restart on redundant CMMs

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 page 1-3

ip ospf interface priority 1

ip ospf interface retrans-interval 5 seconds

ip ospf interface transit-delay 1 second

ip ospf restart-support Disabled

OSPF Quick Steps Configuring OSPF

OSPF Quick Steps

The followings steps are designed to show the user the necessary set of commands for setting up a router to use OSPF:

1 Create a VLAN using the vlan command For example:

-> vlan 5

-> vlan 5 enable

2 Assign a router IP address and subnet mask to the VLAN using the ip interface command. For exam-

ple:

-> ip interface vlan-5 vlan 5 address 120.1.4.1 mask 255.0.0.0

3 Assign a port to the created VLANs using the vlan command. For example:

-> vlan 5 port default 2/1

Note. The port will be statically assigned to the VLAN, as a VLAN must have a physical port assigned to it in order for the router port to function. However, the router could be set up in such a way that mobile ports are dynamically assigned to VLANs using VLAN rules. See the chapter titled “Defining VLAN Rules” in the OmniSwitch 7700/7800/8800 Network Configuration Guide.

4 Assign a router ID to the router using the ip router router-id command. For example:

-> ip router router-id 1.1.1.1

5 Load and enable OSPF using the ip load ospf and the ip ospf status commands. For example:

-> ip load ospf

-> ip ospf status enable

6 Create a backbone to connect this router to others, and an area for the router’s traffic, using the ip ospf

area command. (Backbones are always labeled area 0.0.0.0.) For example:

-> ip ospf area 0.0.0.0

-> ip ospf area 0.0.0.1

7 Enable the backbone and area using the ip ospf area status command. For example:

-> ip ospf area 0.0.0.0 status enable

-> ip ospf area 0.0.0.1 status enable

8 Create an OSPF interface for each VLAN created in Step 1, using the ip ospf interface command. The

OSPF interface should use the same IP address or interface name used for the VLAN router IP created in Step 2. For example:

-> ip ospf interface 120.1.4.1

-> ip ospf interface vlan-5

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Configuring OSPF OSPF Quick Steps

9 Assign the OSPF interface to the area and the backbone using the ip ospf interface area command.

For example:

-> ip ospf interface 120.1.4.1 area 0.0.0.0

-> ip ospf interface vlan-5 area 0.0.0.0

10 Enable the OSPF interfaces using the ip ospf interface status command. For example:

-> ip ospf interface 120.1.4.1 status enable

-> ip ospf interface vlan-5 status enable

11 You can now display the router OSPF settings by using the show ip ospf command. The output gener-

ated is similar to the following:

-> show ip ospf

Router Id = 1.1.1.1, OSPF Version Number = 2, Admin Status = Enabled, Area Border Router? = Yes, AS Border Router Status = Disabled, Route Redistribution Status = Disabled, Route Tag = 0, SPF Hold Time (in seconds) = 10, SPF Delay Time (in seconds) = 5, MTU Checking = Disabled, # of Routes = 0, # of AS-External LSAs = 0, # of self-originated LSAs = 0, # of LSAs received = 0, External LSDB Limit = -1, Exit Overflow Interval = 0, # of SPF calculations done = 1, # of Incr SPF calculations done = 0, # of Init State Nbrs = 0, # of 2-Way State Nbrs = 0, # of Exchange State Nbrs = 0, # of Full State Nbrs = 0, # of attached areas = 2, # of Active areas = 2, # of Transit areas = 0, # of attached NSSAs = 0

Router ID

As set in Step 5

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OSPF Quick Steps Configuring OSPF

12 You can display OSPF area settings using the show ip ospf area command. For example:

-> show ip ospf area 0.0.0.0

Area Identifier = 0.0.0.0, Admin Status = Enabled, Operational Status = Up, Area Type = normal, Area Summary = Enabled, Time since last SPF Run = 00h:08m:37s, # of Area Border Routers known = 1, # of AS Border Routers known = 0, # of LSAs in area = 1, # of SPF Calculations done = 1, # of Incremental SPF Calculations done = 0, # of Neighbors in Init State = 0, # of Neighbors in 2-Way State = 0, # of Neighbors in Exchange State = 0, # of Neighbors in Full State = 0 # of Interfaces attached = 1

Area ID

As set in Step 7

Area Status

As set in Step 8

13 You can display OSPF interface settings using the show ip ospf interface command. For example:

-> show ip ospf interface 120.1.4.1

Interface IP Name = vlan-5 VLAN Id = 5, Interface IP Address = 120.1.4.1, Interface IP Mask = 255.0.0.0, Admin Status = Enabled, Operational Status = Down, OSPF Interface State = Down, Interface Type = Broadcast, Area Id = 0.0.0.0, Designated Router IP Address = 0.0.0.0, Designated Router RouterId = 0.0.0.0, Backup Designated Router IP Address = 0.0.0.0, Backup Designated Router RouterId = 0.0.0.0, MTU (bytes) = 1500, Metric Cost = 1, Priority = 1, Hello Interval (seconds) = 10, Transit Delay (seconds) = 1, Retrans Interval (seconds) = 5, Dead Interval (seconds) = 40, Poll Interval (seconds) = 120, Link Type = Broadcast, Authentication Type = none, # of Events = 0, # of Init State Neighbors = 0, # of 2-Way State Neighbors = 0, # of Exchange State Neighbors = 0, # of Full State Neighbors = 0

VLAN ID

As set in Step 1

Interface ID

As set in Step 9

Interface Status

As set in Step 11

Area ID

As set in Step 7

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Configuring OSPF OSPF Overview

OSPF Overview

The Open Shortest Path First routing (OSPF) is the shortest path first (SPF), or link-state, protocol. OSPF is an interior gateway protocol (IGP) that distributes routing information between routers in a Single Autonomous System (AS). OSPF chooses the least-cost path as the best path.

Each participating router distributes its local state (i.e., the router’s usable interfaces, local networks, and reachable neighbors) throughout the AS by flooding. In a link-state protocol, each router maintains a database describing the entire topology. This database is built from the collected link state advertisements of all routers. Each multi-access network that has at least two attached routers has a designated router and a backup designated router. The designated router floods a link state advertisement for the multi-access network.

When a router starts, it uses the OSPF Hello Protocol to discover neighbors. The router sends Hello packets to its neighbors, and in turn receives their Hello packets. On broadcast and point-to-point networks, the router dynamically detects its neighboring routers by sending Hello packets to a multicast address. On non-broadcast and point-to-multipoint networks, some configuration information is necessary in order to configure neighbors. On all networks (broadcast or non-broadcast), the Hello Protocol also elects a designated router for the network.

Hello. Please respond...

Are you a neighbor...

My link state is...

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Hello. Please respond...

Are you a neighbor...

My link state is...

OSPF Hello Protocol

The router will attempt to form full adjacencies with all of its newly acquired neighbors. Only some pairs, however, will be successful in forming full adjacencies. Topological databases are synchronized between pairs of fully adjacent routers.

Adjacencies control the distribution of routing protocol packets. Routing protocol packets are sent and received only on adjacencies. In particular, distribution of topological database updates proceeds along adjacencies.

Link state is also advertised when a router’s state changes. A router’s adjacencies are reflected in the contents of its link state advertisements. This relationship between adjacencies and link state allows the protocol to detect downed routers in a timely fashion.

Link state advertisements are flooded throughout the AS. The flooding algorithm ensures that all routers have exactly the same topological database. This database consists of the collection of link state advertisements received from each router belonging to the area. From this database each router calculates a shortest-path tree, with itself as root. This shortest-path tree in turn yields a routing table for the protocol.

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OSPF Overview Configuring OSPF

OSPF Areas

OSPF allows collections of contiguous networks and hosts to be grouped together as an area. Each area runs a separate copy of the basic link-state routing algorithm (usually called SPF). This means that each area has its own topological database, as explained in the previous section.

Inter-Area Routing

Intra-Area

Routing

Router 1

Link State Messages

Router 2

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Area 1

Backbone

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Area 2

Intra-Area

Routing

Router 3

Link State Messages

Router 4

OSPF Intra-Area and Inter-Area Routing

An area’s topology is visible only to the members of the area. Conversely, routers internal to a given area know nothing of the detailed topology external to the area. This isolation of knowledge enables the protocol to reduce routing traffic by concentrating on small areas of an AS, as compared to treating the entire AS as a single link-state domain.

Areas cause routers to maintain a separate topological database for each area to which they are connected. (Routers connected to multiple areas are called area border routers). Two routers belonging to the same area have identical area topological databases.

Different areas communicate with each other through a backbone. The backbone consists of routers with contacts between multiple areas. A backbone must be contiguous (i.e., it must be linked to all areas).

The backbone is responsible for distributing routing information between areas. The backbone itself has all of the properties of an area. The topology of the backbone is invisible to each of the areas, while the backbone itself knows nothing of the topology of the areas.

All routers in an area must agree on that area’s parameters. Since a separate copy of the link-state algorithm is run in each area, most configuration parameters are defined on a per-router basis. All routers belonging to an area must agree on that area’s configuration. Misconfiguration will keep neighbors from forming adjacencies between themselves, and OSPF will not function.

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Configuring OSPF OSPF Overview

Classification of Routers

When an AS is split into OSPF areas, the routers are further divided according to function into the following four overlapping categories:

• Internal routers. A router with all directly connected networks belonging to the same area. These

routers run a single copy of the SPF algorithm.

• Area border routers. A router that attaches to multiple areas. Area border routers run multiple copies

of the SPF algorithm, one copy for each attached area. Area border routers condense the topological information of their attached areas for flooding to other areas.

• Backbone routers. A router that has an interface to the backbone. This includes all routers that inter-

face to more than one area (i.e., area border routers). However, backbone routers do not have to be area border routers. Routers with all interfaces connected to the backbone are considered to be internal routers.

• AS boundary routers. A router that exchanges routing information with routers belonging to other

Autonomous Systems. Such a router has AS external routes that are advertised throughout the Autonomous System. The path to each AS boundary router is known by every router in the AS. This classification is completely independent of the previous classifications (i.e., internal, area border, and backbone routers). AS boundary routers may be internal or area border routers, and may or may not participate in the backbone.

Virtual Links

It is possible to define areas in such a way that the backbone is no longer contiguous. (This is not an ideal OSPF configuration, and maximum effort should be made to avoid this situation.) In this case the system administrator must restore backbone connectivity by configuring virtual links.

Virtual links can be configured between any two backbone routers that have a connection to a common non-backbone area. The protocol treats two routers joined by a virtual link as if they were connected by an unnumbered point-to-point network. The routing protocol traffic that flows along the virtual link uses intra-area routing only, and the physical connection between the two routers is not managed by the network administrator (i.e., there is no dedicated connection between the routers as there is with the OSPF backbone).

Router B

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Backbone

Router A

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Area 1

Virtual Link

OSPF Routers Connected with a Virtual Link

In the above diagram, Router A and Router B are connected via a virtual link in Area 1, which is known as a transit area. See “Creating Virtual Links” on page 1-24 for more information.

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 page 1-9

OSPF Overview Configuring OSPF

Stub Areas

OSPF allows certain areas to be configured as stub areas. A stub area is an area with routers that have no AS external Link State Advertisements (LSAs).

In order to take advantage of the OSPF stub area support, default routing must be used in the stub area. This is accomplished by configuring only one of the stub area’s border routers to advertise a default route into the stub area. The default routes will match any destination that is not explicitly reachable by an intraarea or inter-area path (i.e., AS external destinations).

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Backbone

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Backbone

Area 1

(stub)

Area 2

Area 3

(stub)

OSPF Stub Area

Area 1 and Area 3 could be configured as stub areas. Stub areas are configured using the OSPF ip ospf area command, described in “Creating an Area” on page 1-17. For more overview information on areas,

see “OSPF Areas” on page 1-8.

The OSPF protocol ensures that all routers belonging to an area agree on whether the area has been configured as a stub. This guarantees that no confusion will arise in the flooding of AS external advertisements.

Two restrictions on the use of stub areas are:

• Virtual links cannot be configured through stub areas.

• AS boundary routers cannot be placed internal to stub areas.

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Configuring OSPF OSPF Overview

Not-So-Stubby-Areas

NSSA, or not-so-stubby area, is an extension to the base OSPF specification and is defined in RFC 1587. An NSSA is similar to a stub area in many ways: AS-external LSAs are not flooded into an NSSA and virtual links are not allowed in an NSSA. The primary difference is that selected external routing information can be imported into an NSSA and then redistributed into the rest of the OSPF routing domain. These routes are imported into the NSSA using a new LSA type: Type-7 LSA. Type-7 LSAs are flooded within the NSSA and are translated at the NSSA boundary into AS-external LSAs so as to convey the external routing information to other areas.

NSSAs enable routers with limited resources to participate in OSPF routing while also allowing the import of a selected number of external routes into the area. For example, an area which connects to a small external routing domain running RIP may be configured as an NSSA. This will allow the import of RIP routes into this area and the rest of the OSPF routing domain and at the same time, prevent the flooding of other external routing information (learned, for example, through RIP) into this area.

All routers in an NSSA must have their OSPF area defined as an NSSA. To configure otherwise will ensure that the router will be unsuccessful in establishing an adjacent in the OSPF domain.

Totally Stubby Areas

In Totally Stubby Areas the ABR advertises a default route to the routers in the totally stubby area but does not advertise any inter-area or external LSAs. As a result, routers in a totally stubby area know only the routes for destination networks in the stub area and have a default route for any other destination outside the stub.

Note. Virtual links cannot be configured through totally stubby areas.

The router memory is saved when using stub area networks by filtering Type 4 and 5 LSAs. This concept has been extended with Totally Stubby Areas by filtering Type 3 LSAs (Network Summary LSA) in addition to Type 4 and 5 with the exception of one single Type 3 LSA used to advertise a default route within the area.

The following is an example of a simple totally stubby configuration with Router B being an ABR between the backbone area 0 and the stub area 1. Router A is in area 1.1.1.1, totally stubby area:

OSPF Area 0

192.168.50.0/24

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Router A

192.168.12.1

OSPF Area 1

Totally Stubby

192.168.12.2

Router B

Totally Stubby Area Example

Note. See “Configuring a Totally Stubby Area” on page 1-19 for information on configuring Totally

Stubby Areas.

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OSPF Overview Configuring OSPF

Equal Cost Multi-Path (ECMP) Routing

Using information from its continuously updated databases, OSPF calculates the shortest path to a given destination. The shortest path is determined from metric values at each hop along a path. At times, two or more paths to the same destination will have the same metric cost.

In the network illustration below, there are two paths from Source router A to Destination router B. One path traverses two hops at routers X and Y and the second path traverses two hops at M and N. If the total cost through X and Y to B is the same as the cost via M and N to B, then these two paths have equal cost. In this version of OSPF both paths will be stored and used to transmit data.

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A-> X-> Y-> B = A-> M-> N-> B

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Source (A)

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Destination (B)

Multiple Equal Cost Paths

Delivery of packets along equal paths is based on flows rather than a round-robin scheme. Equal cost is determined based on standard routing metrics. However, other variables, such as line speed, are not considered. So it is possible for OSPF to decide two paths have an equal cost even though one may contain faster links than another.

Non-Broadcast OSPF Routing

OSPF can operate in two modes on non-broadcast networks: NBMA and point-to-multipoint. The interface type for the corresponding network segment should be set to non-broadcast or point-to-multipoint, respectively.

For non-broadcast networks neighbors should be statically configured. For NBMA neighbors the eligibility option must be enabled for the neighboring router to participate in Designated Router (DR) election.

For the correct working of an OSPF NBMA network, a fully meshed network is mandatory. Also, the neighbor eligibility configuration for a router on every other router should match the routers interface priority configuration.

See “Configuring Static Neighbors” on page 1-29 for more information and setting up static neighbors.

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Configuring OSPF OSPF Overview

Graceful Restart on Switches with Redundant CMMs

OmniSwitch 7700/7800/8800 chassis with two Chassis Management Modules (CMMs) can support redundancy where if the primary CMM fails or goes offline for any reason, the secondary CMM is instantly notified. The secondary CMM automatically assumes the primary role. This switch between the primary and secondary CMMs is known as takeover.

When a takeover occurs, which can be planned (e.g., the users performs the takeover) or unplanned (e.g., the primary CMM unexpectedly fails), an OSPF router must re-establish full adjacencies with all its previously fully adjacent neighbors. This time period between the restart and the re-establishment of adjacencies is termed graceful restart.

In the network illustration below, a helper router, Router Y, monitors the network for topology changes. As long as there are none, it continues to advertise its LSAs as if the restarting router, Router X, had remained in continuous OSPF operation (i.e., Router Y’s LSAs continue to list an adjacency to Router X over network segment S, regardless of the adjacency’s current synchronization state.)

Router B

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Restarting Router X

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Helping Router Y

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Network Segment S

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Router A

Router C

OSPF Graceful Restart Helping and Restarting Router Example

If the restarting router, Router X, was the Designated Router (DR) on network segment S when the helping relationship began, the helper neighbor, Router Y, maintains Router X as the DR until the helping relationship is terminated. If there are multiple adjacencies with the restarting Router X, Router Y will act as a helper on all other adjacencies.

Note. See “Configuring Redundant CMMs for Graceful Restart” on page 1-30 for more information on configuring graceful restart.

OmniSwitch 7700/7800/8800 Advanced Routing Configuration Guide April 2006 page 1-13

Configuring OSPF Configuring OSPF

Configuring OSPF

Configuring OSPF on a router requires several steps. Depending on your requirements, you may not need to perform all of the steps listed below.

By default, OSPF is disabled on the router. Configuring OSPF consists of these tasks:

• Set up the basics of the OSPF network by configuring the required VLANs, assigning ports to the

VLANs, and assigning router identification numbers to the routers involved. This is described in

“Preparing the Network for OSPF” on page 1-15.

• Enable OSPF. When the image file for advanced routing is installed, you must load the code and enable

OSPF. The commands for enabling OSPF are described in “Activating OSPF” on page 1-16.

• Create an OSPF area and the backbone. The commands to create areas and backbones are described in

“Creating an OSPF Area” on page 1-17.

• Set area parameters (optional). OSPF will run with the default area parameters, but different networks

may benefit from modifying the parameters. Modifying area parameters is described in “Configuring

Stub Area Default Metrics” on page 1-18.

• Create OSPF interfaces. OSPF interfaces are created and assigned to areas. Creating interfaces is

described in “Creating an Interface” on page 1-21, and assigning interfaces is described in “Assigning

an Interface to an Area” on page 1-21.

• Set interface parameters (optional). OSPF will run with the default interface parameters, but different

networks may benefit from modifying the parameters. Also, it is possible to set authentication on an interface. Setting interface authentication is described in “Interface Authentication” on page 1-22, and modifying interface parameters is described in “Modifying Interface Parameters” on page 1-23.

• Configure virtual links (optional). A virtual link is used to establish backbone connectivity when two

backbone routers are not physically contiguous. To create a virtual link, see “Creating Virtual Links”

on page 1-24.

• Create a redistribution policy (optional). A redistribution policy allows for the control of how routes

are advertised into OSPF from outside the Autonomous System. Once a policy is created, redistribution must be enabled. Creating a redistribution policy is described in “Creating A Redistribution

Policy” on page 1-26, and enabling redistribution is described in “Enabling Redistribution” on page 1-25.

• Create redistribution filters (optional). A redistribution filter controls whether routes are advertised in

the OSPF network. Creating a redistribution filter is described in “Creating a Redistribution Filter” on

page 1-26.

• Configuring router capabilities (optional). There are several commands that influence router operation.

These are covered briefly in a table in “Configuring Router Capabilities” on page 1-28.

• Creating static neighbors (optional). These commands allow you to statically configure neighbors. See

“Configuring Static Neighbors” on page 1-29.

• Configuring redundant CMMs for graceful OSPF restart (optional). Configuring switches with redun-

dant CMMs for graceful restart is described in “Configuring Redundant CMMs for Graceful Restart”

on page 1-30.

At the end of the chapter is a simple OSPF network diagram with instructions on how it was created on a router-by-router basis. See “OSPF Application Example” on page 1-31 for more information.

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