Rpr Overview - Cisco WS-C6506 Software Manual

Chapter 24 Configuring NSF with SSO MSFC Redundancy
In NSF/SSO mode, one MSFC is active and the other MSFC is in a hot-standby mode. The hot-standby
MSFC maintains a constant readiness state by receiving state information from the active MSFC. At any
given moment, the standby MSFC may be called on by the supervisor engine to take over the
responsibilities held by the active MSFC. The supervisor engine monitors the active MSFC and if the MSFC
does not respond, the supervisor engine declares the MSFC as lost or down and proceeds to reset the MSFC.
The standby MSFC has the up-to-date state information necessary to resume processing (the standby
MSFC is fully initialized, but the VLANs are kept in an administrative down state until a switchover occurs).
With NSF, the switching modules and switch fabric continue to forward packets while the MSFC
switchover is in progress.
Detected failures of hardware or CLI commands may also cause a switchover.
Note
High availability on the supervisor engine operates independent of the MSFC high-availability feature.
Note
However, you must enable high availability on the supervisor engine must be enabled to ensure the correct
operation of the MSFC SSO feature.
If you run the MSFC in SSO mode and fail to run the high-availability feature on the supervisor engine, any
switchover that may occur will result in a nonstateful switchover and the standby MSFC will reset itself and
reload at the time of the switchover. This reset/reload of the standby MSFC occurs because there is
insufficient state information on the supervisor engine to support a stateful switchover of the MSFC. This
reset/reload of the standby MSFC interrupts service.

RPR Overview

RPR+ mode is not supported.
Note
RPR is a cold standby mode. When a switchover occurs, the standby MSFC must go completely through
its initialization. RPR mode is used primarily for the fast software upgrade (FSU). (See the
Software Upgrade" section on page
the standby MSFC, however, it is not processed in any way until the switchover occurs. The running
configuration is not synchronized to the standby MSFC.
When the active MSFC boots completely, no state information is exchanged between the MSFCs. If the
active MSFC fails, the standby MSFC processes its startup configuration file and begins its initialization.
If there is an image compatibility problem, the active MSFC boots fully, but the standby MSFC suspends
its startup before processing the startup configuration file. If the active MSFC fails, a switchover is
triggered and the suspended standby MSFC begins to initialize and become the active MSFC.
High availability on the supervisor engine does not have to be enabled to run RPR on the MSFC.
Note
OL-8978-04
24-14.) In RPR mode, the startup configuration is synchronized to
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
RPR Overview
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