Cisco Catalyst 4500 series Administration Manual page 343

Configuring the Cisco IOS XE In Service Software
Upgrade Process
An ISSU upgrade from any release prior to IOS XE 3.6.0E to 3.6.0E or later is unsupported for IOS XE
Note
supervisor engines (SUP7-E, SUP7L-E and SUP8-E).
Refer to
Note
ISSU is available in Cisco IOS XE Release 3.1.0.SG and later releases.
Note
Operating on redundant systems, the In Service Software Upgrade (ISSU) process allows Cisco IOS XE
software to be updated or otherwise modified while packet forwarding continues. In most networks,
planned software upgrades are a significant cause of downtime. ISSU allows Cisco IOS XE software to
be upgraded while packet forwarding continues. This increases network availability and reduces
downtime caused by planned software upgrades. This document provides information about ISSU
concepts and describes the steps taken to perform ISSU in a system.
Topics include:
Prerequisites to Performing ISSU, page 7-2
•
About Performing ISSU, page 7-3
•
How to Perform the ISSU Process, page 7-16
•
Cisco High Availability Features in Cisco IOS XE 3.1.0SG, page 7-39
•
For complete syntax and usage information for the switch commands used in this chapter, see the Cisco
Note
Catalyst 4500 Series Switch Command Reference and related publications at this location:
http://www.cisco.com/en/US/products/hw/switches/ps4324/index.html
If a command is not in the Catalyst 4500 Series Switch Command Reference, you can locate it in the
Cisco IOS library. See the Cisco IOS Command Reference and related publications at this location:
http://www.cisco.com/en/US/products/ps6350/index.html
OL-30933-01
Chapter 5, "Configuring Virtual Switching Systems"
Software Configuration Guide—Release IOS XE 3.6.0SG and IOS 15.2(2)SG
7
C H A P T E R
for details on VSS ISSU.
7-1