How To Perform The Issu Process - Cisco Catalyst 4500 series Administration Manual

Chapter 5 Configuring Virtual Switching Systems

How to Perform the ISSU Process

Unlike SSO, which is a mode of operation for the device and a prerequisite for performing ISSU, the
ISSU process is a series of steps performed while the switch is in operation. The steps result in an
upgrade to new or modified Cisco IOS XE software, and have a minimal impact to traffic.
Note For an illustration of the process flow for ISSU, refer to
This section includes the following topics:
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Verifying the ISSU Software Installation
During the ISSU process, there are five valid states: disabled, init, load version, run version, and system
reset. Use the show issu state command to obtain the current ISSU state:
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You can verify the ISSU software upgrade by entering show commands to provide information on the
state of the during the ISSU process:
Command or Action
Step 1
Switch> enable
Step 2
Switch# show issu state [detail]
OL-30933-01
Verifying the ISSU Software Installation, page 5-63
Verifying Redundancy Mode Before Beginning the ISSU Process, page 5-64
Verifying the ISSU State Before Beginning the ISSU Process, page 5-65
ISSU using the Four-command Sequence: Step 1 (loadversion), page 5-67
ISSU using the Four-command Sequence: Step 2 (runversion), page 5-68
ISSU using the Four Command Sequence: Step 3 (acceptversion), page 5-70
ISSU using the Four Command Sequence: Step 4 (commitversion), page 5-71
Using changeversion to Automate an ISSU Upgrade, page 5-72
Aborting a Software Upgrade During ISSU, page 5-78
Configuring the Rollback Timer to Safeguard Against Upgrade Issues, page 5-79
The ISSU Compatibility Matrix, page 5-81
Disabled state—The state for the standby supervisor engine while this supervisor engine is resetting.
Init state—The initial state for two supervisor engines, one active and one standby, before the ISSU
process is started. It is also the final state after the ISSU process completes.
Load version (LV) state—The standby supervisor engine is loaded with the new version of Cisco
IOS XE software.
Run version (RV) state—The issu runversion command forces the switchover of the supervisor
engines. The newly active supervisor engine runs the new Cisco IOS XE software image.
While running ISSU, if both supervisor engines are reset (because of a power outage, for example),
the ISSU context is lost and the system returns to the Init state. Both supervisor engines return to
the old software.
Figure
Purpose
Enables privileged EXEC mode.
Enter your password if prompted.
Displays the current state of the ISSU process.
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)SG
In-Service Software Upgrade (ISSU) on a VSS
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