Rpr and sso redundancy – Cisco 6500 User Manual
Page 12
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Cisco IOS Software Configuration Guide, Release 12.2SX
OL-13013-06
Chapter 4 Configuring Virtual Switching Systems
Understanding Virtual Switching Systems
RPR and SSO Redundancy
A VSS operates with stateful switchover (SSO) redundancy if it meets the following requirements:
•
Both supervisor engines must be running the same software version.
•
VSL-related configuration in the two chassis must match.
•
PFC mode must match.
•
SSO and nonstop forwarding (NSF) must be configured on each chassis.
See the
“SSO Dependencies” section on page 4-25
for additional details about the requirements for SSO
redundancy on a VSS. See
Chapter 6, “Configuring NSF with SSO Supervisor Engine Redundancy”
for
information about configuring SSO and NSF.
With SSO redundancy, the VSS standby supervisor engine is always ready to assume control following
a fault on the VSS active supervisor engine. Configuration, forwarding, and state information are
synchronized from the VSS active supervisor engine to the redundant supervisor engine at startup and
whenever changes to the VSS active supervisor engine configuration occur. If a switchover occurs,
traffic disruption is minimized.
If a VSS does not meet the requirements for SSO redundancy, the VSS will use route processor
redundancy (RPR). In RPR mode, the VSS active supervisor engine does not synchronize configuration
changes or state information with the VSS standby. The VSS standby supervisor engine is only partially
initialized and the switching modules on the VSS standby supervisor are not powered up. If a switchover
occurs, the VSS standby supervisor engine completes its initialization and powers up the switching
modules. Traffic is disrupted for the normal reboot time of the chassis.
The VSS normally runs stateful switchover (SSO) between the VSS active and VSS standby supervisor
engines (see
). The VSS determines the role of each supervisor engine during initialization.
The supervisor engine in the VSS standby chassis runs in hot standby state. The VSS uses the VSL link
to synchronize configuration data from the VSS active to the VSS standby supervisor engine. Also,
protocols and features that support high availability synchronize their events and state information to the
VSS standby supervisor engine.
Figure 4-7
Chassis Roles in a VSS
Active
Supervisor
Linecard 1
Linecard 2
Linecard N
Standby
Supervisor
Linecard 1
Linecard 2
Linecard N
Active chassis
Standby chassis
181326
VSL