Single Router Mode Redundancy - Cisco WS-C6506 Software Manual

Chapter 23 Configuring Redundancy
Scenario 5: Designated MSFC Goes Down
In this scenario, the nondesignated MSFC becomes the designated MSFC, the configuration
synchronization is disabled, and the configuration mode on the CLI is now available.
When the previously designated MSFC comes back up, it becomes the nondesignated MSFC; see the
"Scenario 4: Nondesignated MSFC Comes Up" section on page

Single Router Mode Redundancy

These sections describe how to configure single router mode (SRM) redundancy:
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SRM redundancy is an alternative to the internally redundant (dual) MSFC2 configurations where both
MSFC2s are active at the same time. In SRM redundancy, only the designated router is visible to the
network at any given time. The nondesignated router is booted up completely and participates in the
configuration synchronization which is automatically enabled when entering SRM. All configuration
following the "alt" keyword is ignored in SRM; the nondesignated router's configuration is exactly the
same as the designated router but its interfaces are kept in a line down state and are not visible to the
network. The processes, such as the routing protocols, are created on the nondesignated router and the
designated router, but all the nondesignated router interfaces are in a line down state; they do not send
or receive updates from the network.
When the designated router fails, the nondesignated router changes its state from a nondesignated router
to a designated router and its interface state changes to link up. The newly designated router builds up
its routing table while the existing supervisor engine switch processor entries are used to forward the
Layer 3 traffic. The switch processor continues to forward the Layer 3 packets using the old entries. After
a predefined time, the newly designated router downloads the new Layer 3 switching information to the
switch processor.
Note With Cisco IOS Release 12.1(11b)E and later releases, you can specify the transition time that the
newly designated router waits before downloading the new Layer 3 switching information to the
supervisor engine switch processor. For configuration details, see the
Time on the Newly Designated Active Router" section on page
Hardware and Software Requirements
To configure SRM redundancy, you must have the following hardware and software:
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OL-8978-04
Hardware and Software Requirements, page 23-43
SRM Redundancy Configuration Guidelines, page 23-44
Configuring Single Router Mode Redundancy on Supervisor Engine 720, page 23-45
Configuring Single Router Mode Redundancy on Supervisor Engine 1 or Supervisor Engine 2,
page 23-45
Upgrading Images with Single Router Mode Enabled, page 23-48
Getting Out of Single Router Mode, page 23-49
A single chassis with two identical supervisor engine daughter card configurations:
Supervisor Engine 32 with Policy Feature Card 3B/3BXL (PFC3B/PFC3BXL) and MSFC2A
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– Supervisor Engine 720 with PFC3A/PFC3B/PFC3BXL and MSFC3
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
MSFC Redundancy
23-41.
"Specifying the Transition
23-47.
23-43