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White Paper

High Availability for the Cisco Catalyst

6500

Series Switches

Figure 1

The Cisco Catalyst 6500
Series WS-6503,
WS-C6506, WS-C6509,
WS-C6509-NEBS, and
WS-C6513

Overview

Cisco Catalyst

®

6500 Series multilayer

switches have become an essential component

of a sound network design in today’s enterprise

and service provider environments. Having

such a critical role, the Cisco Catalyst 6500

Series must provide a reliable switching

platform, and offer high performance and

intelligent network services. The high

availability of the Cisco Catalyst 6500 Series

even has the capability to maintain an IP phone

call during supervisor engine failover. This

paper discusses how the Cisco Catalyst 6500

Series provides high system availability

through hardware and software redundancy

features, and focuses specifically on the

following three areas:

Fabric redundancy of the Switch Fabric

Module (SFM)

Supervisor engine redundancy with the Cisco

Catalyst Operating System (Catalyst OS), High

Availability feature, which includes the stateful

protocol redundancy and image versioning

functions

Multilayer Switch Feature Card (MSFC)

Cisco IOS

®

Software redundancy

features—Dual Router Mode (DRM),

Configuration-Synchronization

(config-sync), and Single Router

Mode (SRM).

This paper is based on the hybrid software

model for the Cisco Catalyst 6500 Series

(Cisco Catalyst OS on the supervisor engine,

Cisco IOS Software on the MSFC) and not on

the Cisco IOS Software model (native Cisco

IOS Software). All feature set references will

be specifically described as a Cisco Catalyst

OS feature on a supervisor engine or a Cisco

IOS Software feature on an MSFC. The Cisco

Catalyst OS High Availability feature was first

introduced in the Cisco Catalyst OS 5.4 release

and is available for both Cisco Catalyst

Supervisor Engine 1A and Catalyst Supervisor

Engine 2. Support for DRM began in Cisco

IOS Software Release 12.0(7)XE1. The MSFC

config-sync redundancy feature for DRM is

supported in Cisco IOS Software Release

12.1(3a)E4 for both the MSFC and MSFC2.

The MSFC SRM feature was first supported

with Cisco Catalyst OS 6.3.1 and Cisco IOS

Software Release 12.1(8)E2 for the MSFC2.

This paper is the second version of the original

that was written in September 2000. This

version includes some updated sections for

more precise understanding and a discussion of

SRM.

Although component-level redundancy is very

important, a high-availability network design

relies on the proper combination of individual

system redundancy and overall network