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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 asound network designin today’senterprise
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 hasthe capability tomaintain anIP 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
CatalystOperatingSystem(CatalystOS),High
Availabilityfeature,whichincludes thestateful
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 inthe CiscoCatalyst OS5.4 release
and is available for both Cisco Catalyst
Supervisor Engine 1Aand Catalyst Supervisor
Engine 2. Support for DRM began in Cisco
IOS Software Release12.0(7)XE1. TheMSFC
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 secondversion of the original
that was written in September 2000. This
version includes some updated sections for
moreprecise understandinganda discussionof
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