Cisco Catalyst 4500 Series, Software Configuration Manual

Page: 504 / 2086

11-2
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 11 Configuring Supervisor Engine Redundancy Using RPR and SSO on Supervisor Engine 6-E and Supervisor
About Supervisor Engine Redundancy
About Supervisor Engine Redundancy
These sections describe supervisor engine redundancy:
•
Overview, page 11-2
• RPR Operation, page 11-2
•
SSO Operation, page 11-3
Overview
With supervisor engine redundancy enabled, if the active supervisor engine fails or if a manual
switchover is performed, the redundant supervisor engine becomes the active supervisor engine. The
redundant supervisor engine has been automatically initialized with the startup configuration of the
active supervisor engine, shortening the switchover time (30 seconds or longer in RPR mode, depending
on the configuration; subsecond in SSO mode).
In addition to the reduced switchover time, supervisor engine redundancy supports the following:
• Online insertion and removal (OIR) of the redundant supervisor engine.
Supervisor engine redundancy allows OIR of the redundant supervisor engine for maintenance.
When the redundant supervisor engine is inserted, the active supervisor engine detects its presence,
and the redundant supervisor engine boots into a partially-initialized state in RPR mode and a
fully-initialized state in SSO mode.
• Software upgrade. See the “Performing a Software Upgrade” section on page 11-13 .
To minimize down time during software changes on the supervisor engine, load the new image on
the redundant supervisor engine, and conduct a switchover.
When power is first applied to a switch, the supervisor engine that boots first becomes the active
supervisor engine and remains active until a switchover occurs.
A switchover occurs when one or more of the following events take place:
• The active supervisor engine fails (due to either hardware or software function) or is removed.
•
A user forces a switchover.
• A user reloads the active supervisor engine.
RPR Operation
RPR is supported in Cisco IOS Release 12.2(12c)EW and later releases. When a redundant supervisor
engine runs in RPR mode, it starts up in a partially-initialized state and is synchronized with the
persistent configuration of the active supervisor engine.
Note
Persistent configuration includes the following components: startup-config, boot variables,
config-register, and VLAN database.
The redundant supervisor engine pauses the startup sequence after basic system initialization, and in the
event that the active supervisor engine fails, the redundant supervisor engine becomes the new active
supervisor engine.