Cisco Catalyst 4500 Series - Page 365

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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.0E and IOS 15.2(5)E
Chapter 7 Configuring the Cisco IOS In-Service Software Upgrade Process
About ISSU
After a switchover (NSF or SSO, not RPR), the standby supervisor engine takes over as the new active
supervisor engine (see Figure 7-6).
Figure 7-6 Switch Over to Standby Supervisor Engine
Line cards
Old
Active
Supervisor
Engine
Cisco IOS
12.x(y)S
Cisco IOS
12.x(y)S
Cisco IOS
12.x(y)S
NSF/SSO
Switchover
NSF/SSO
Switchover
Run new version
of Cisco IOS
on standby
Cisco IOS
12.x(z)S
New
Active
Supervisor
Engine
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