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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 24 Configuring NSF with SSO MSFC Redundancy
Hardware and Software Requirements
Hardware and Software Requirements
This sections describes the hardware and software requirements for configuring NSF/SSO:
•
Supported supervisor engines— Supervisor Engine 2, Supervisor Engine 720, and Supervisor
Engine 32 (NSF/SSO is not supported with Supervisor Engine 1).
•
Supported MSFCs—MSFC2, MSFC2A, and MSFC3 (the MSFC is not supported).
•
The redundant supervisor engines must be the same type with the same model PFC and MSFC.
•
Catalyst software release 8.5(1) and later releases.
Note
If SSO is enabled on the MSFC, you must enable high availability on the supervisor engine
before
upgrading to supervisor engine software release 8.5(1) and later releases. Use the
set
system highavailability enable
command to enable high availability on the supervisor
engine.
•
Cisco IOS Release 12.2(18)SXF and later releases.
Understanding How NSF/SSO Works
Note
SSO replaces single router mode (SRM) and dual router mode (DRM). There is no support for these
high-availability modes. For SRM and DRM CLI processing details, see the
“Configuration Guidelines
and Restrictions” section on page 24-4
.
The Catalyst operating system that runs on the supervisor engine provides a Layer 2 high availability for
redundant supervisor engines. Cisco IOS Release 12.2(18)SXF and later releases with NSF and SSO that
run on the MSFC provide Layer 3 (and above) high availability for redundant MSFCs. MSFC SSO
high-availability benefits are as follows:
•
Reduced downtime.
•
The ability to upgrade software without shutting down the MSFC.
•
The ability to detect a failure of the active MSFC and allow the standby MSFC to take over the
system with minimal drops in existing traffic flows.
When the system comes up, after the supervisor engine completes its initialization and prepares itself
for operation, the supervisor engine sends an SCP inventory message to both MSFCs. The inventory
message contains information about which MSFCs are present in the system and as other operational
state information. From a high-availability perspective, the inventory message is important because it
contains information that dictates which MSFC will be the active MSFC and which will be the standby
MSFC.
During the startup of the standby MSFC, image version information is exchanged between MSFCs and
one of the following occurs:
•
If the image version information matches and both MSFCs are configured as SSO or have the default
(SSO) configuration, the system runs in SSO mode.
•
If the image version information does not match or if one of the MSFCs is configured for route
processor redundancy (RPR), the system runs in RPR mode.
