Section 8-4. MSFC Redundancy with Single Router Mode

8-4. MSFC Redundancy with Single Router Mode

• Only the Catalyst 6000 supports redundant supervisor engines with redundant route processors (MSFC/MSFC2).

• Only one MSFC is designated and active; the other is booted up, synchronizes its configuration with the active MSFC, starts any routing protocol processes, but keeps all interfaces in the "line down" state so that no network traffic is exchanged.

• Only the designated and active MSFC is involved in creating MLS flow cache entries for the switching engine and in creating and downloading the CEF FIB and adjacency tables to the PFC2 switching engine.

• In the event of a failure, single router mode (SRM) causes the nondesignated MSFC to bring its interfaces up and allow its routing protocols to converge. During this time, the existing Layer 3 switching information supplied by the failed MSFC continues to be used by the designated Supervisor PFC until the new MSFC can provide an update.

• Both MSFC modules must run the same Cisco IOS Software imageSoftware Release 12.1(8a)E2 or later.

• The Supervisor modules must run in high-availability mode to support SRM, using Supervisor Engine Software Release 6.3(1) or later.

• Hot Standby Router Protocol (HSRP) is not necessary in SRM, because only one MSFC is active in the chassis at any one time. However, you should use HSRP if you have other MSFC or Layer 3 devices that have a presence on the same VLANs as the SRM MSFC. These other devices can then act as redundant gateways on those VLANs.

Configuration

1.

Enable Supervisor high availability:

COS	set system highavailability enable
IOS	N/A

High availability is required on the redundant Supervisor engines so that the Layer 3 switching information can be properly maintained across a Supervisor or PFC failure. This information is used during an MSFC failure, while the nondesignated MSFC waits for its routing information to converge.

2.

Enable SRM on the designated MSFC:

COS	N/A
IOS	(global) redundancy (redundancy) high-availability (highavailability) single-router-mode

The MSFC that has SRM configured first will become designated. SRM will not become active until both MSFCs have SRM enabled.

3.

(Optional) Adjust the failover convergence delay time:

COS	N/A
IOS	[View full width] (highavailability) single-router-mode failover table-update-delay seconds

When a nondesignated MSFC detects a failure and becomes active, it waits for seconds (default 120 seconds) before sending any new Layer 3 switching information to the switching engine (PFC/PFC2). You can tune this delay time to allow any configured routing protocols to properly converge.

4.

Enable SRM on the nondesignated MSFC:

COS	N/A
IOS	(global) redundancy (redundancy) high-availability (highavailability) single-router-mode

The nondesignated MSFC will now accept its configuration from the designated MSFC.

5.

Save the running configuration on the designated MSFC:

COS	N/A
IOS	copy running-config startup-config

The designated MSFC configuration will automatically be saved to the nondesignated MSFC.

6.

Reload the nondesignated MSFC:

IOS

 (exec) reload 

After the reload, the nondesignated MSFC enters SRM mode with its interfaces in the "line down" state.

Displaying Information About SRM

You can use the switch commands in Table 8-5 to display helpful information about SRM redundancy.

Table 8-5. Commands to Display SRM Information

Display Function	Switch OS	Command
SRM status	COS	N/A
	IOS	(exec) show redundancy