About Performing Issu - Cisco Catalyst 4500 Series Software Configuration Manual

Chapter 8 Configuring the Cisco IOS XE In Service Software Upgrade Process
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About Performing ISSU

Do not make any hardware changes while performing ISSU.
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Before you perform ISSU, you should understand the following concepts:
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auto-boot must be enabled for ISSU to succeed.
Stateful Switchover (SSO) must be configured and the standby supervisor engine should be in
STANDBY HOT state.
These commands indicate whether SSO is enabled: show module, show running-config,
show redundancy state.
If you do not have SSO enabled, see the Stateful Switchover document for further information on
how to enable and configure SSO.
Nonstop Forwarding (NSF) must be configured and working properly. If you do not have NSF
enabled, see the Cisco Nonstop Forwarding document for further information on how to enable and
configure NSF.
Before you perform ISSU, ensure that the file system for both the active and the standby supervisor
engines contains the new ISSU-compatible IOS XE software. The current Cisco IOS XE version
running in the system must also support ISSU.
You can enter various commands on the Catalyst 4500 series switch to determine supervisor engine
versioning and Cisco IOS XE software compatibility. Alternatively, you can use the ISSU
application on Cisco Feature Navigator to determine this.
If you enter the no ip routing command, ISSU falls back from SSO to RPR mode, resulting in traffic
loss.
Autoboot is turned on and the current booted image matches the one specified in the BOOT
environmental variable. For details on how to configure and verify these, please refer to
the Boot Field and Using the boot Command, page
If you enter the no ip routing command, ISSU falls back from SSO to RPR mode, resulting in traffic
loss.
Stateful Switchover, page 8-4
NSF, page 8-6
ISSU Process, page 8-7
Performing an ISSU Upgrade: 2 Methods, page 8-12
Changeversion Process, page 8-13
Guidelines for Performing ISSU, page 8-14
Compatibility Matrix, page 8-14
SNMP Support for ISSU, page 8-15
Compatibility Verification Using Cisco Feature Navigator, page 8-15
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
About Performing ISSU
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