Cisco Catalyst 4500 series Administration Manual page 307

Chapter 6 Configuring the Cisco IOS In-Service Software Upgrade Process
An ISSU-capable switch consists of two supervisor engines (active and standby) and one or more line
cards. Before initiating the ISSU process, copy the Cisco IOS software into the file systems of both
supervisor engines (see
Note In the following figure, Cisco IOS 12.x(y)S represents the current version of Cisco IOS.
Figure 6-4
OL-30933-01
Figure 6-4).
Install/Copy New Version of Cisco IOS Software on Both Supervisor Engines
Install new version
of Cisco IOS
on active and standby
Supervisor Engines
Cisco IOS Cisco IOS
12.x(y)S 12.x(y)S
Cisco IOS Cisco IOS
12.x(z)S
12.x(z)S
Active
NSF/SSO
Supervisor Supervisor
Engine
Line cards
Software Configuration Guide—Release IOS XE 3.6.0SG and IOS 15.2(2)SG
Cisco IOS Cisco IOS
12.x(y)S 12.x(y)S
Cisco IOS Cisco IOS
12.x(z)S
12.x(z)S
Standby
Engine
About ISSU
6-7