CHAPTER
7-1
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.0E and IOS 15.2(5)E
7
Configuring the Cisco IOS In-Service Software
Upgrade Process
Note Starting with Cisco IOS 12.2(31)SGA, ISSU is supported on the Catalyst 4500. All line cards are
supported.
Operating on redundant systems, the In-Service Software Upgrade (ISSU) process allows Cisco IOS
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 software to be
modified 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.
This section includes these topics:
• Prerequisites to Performing ISSU, page 7-1
• About ISSU, page 7-2
• Performing the ISSU Process, page 7-15
• Related Documents, page 7-42
Note For complete syntax and usage information for the switch commands used in this chapter, see the
Cisco IOS Command Reference Guides for the Catalyst 4500 Series Switch.
If a command is not in the Cisco Catalyst 4500 Series Switch Command Reference , you can locate it in
the Cisco IOS Master Command List, All Releases.
Prerequisites to Performing ISSU
Before performing ISSU, you need to meet these prerequisites:
• Image type of the existing and target image must match. For example, you cannot upgrade from an
IP Base image to an Enterprise Services image (and vice versa) without experiencing several
minutes of traffic loss.
Note A similar limitation applies between crypto and non-crypto images.
To Next Page
Loading...
Need help?
General
