Cisco Catalyst 4500 series Administration Manual page 275

Chapter 5 Configuring Virtual Switching Systems
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ISSU using the four-command sequence
The manual ISSU upgrade process involves issuing four distinct ISSU EXEC commands in sequence
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A fifth command, issu abortversion, enables you to abort the ISSU upgrade process at any time, and to
revert to the initial system state.
These four commands take the VSS through a series of states that culminate in the Active and standby
supervisor engines running the post-upgrade IOS XE image. The VSS continues to operate throughout
the entire process; however as explained in
VSS, page
switch that is undergoing a reboot.
Figure 5-11
the sequence of four commands entered. It also shows the effect of the issu abortversion command at
any given point during the process.
Figure 5-11 States of VSS Active and Standby during Command Execution
OL-30933-01
automatically; using a single command
issu loadversion
issu runversion
issu acceptversion
issu commitversion
5-57, service is disrupted on network links that terminate on interfaces that reside in the
depicts the states through which the VSS Active and standby supervisor engines progress as
A
A
Traffic and Network Protocol Disruption During ISSU in a
A
A
A
A
A
A
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)SG
In-Service Software Upgrade (ISSU) on a VSS
A
Chassis running
the pre-upgrade
version
Chassis
undergoing
reboot
Chassis running
the post-upgrade
image
SSO Active
A
Switch.
5-59