SRM and IP Multicast
With SRM, the VLAN interfaces on the nondesignated router are in a down state. Even after a failover, these interfaces will not move into an up state until the supervisor engine verifies that the VLAN has at least one connected physical interface in the forwarding state. This interruption causes the supervisor engine to delete all multicast entries in the PFCx and this disrupts multicast forwarding. As an enhancement to the original SRM implementation, Cisco Catalyst OS release 7.1 provides support for IP Multicast stateful redundancy. When SRM is enabled in Cisco Catalyst OS version 7.1, the multicast flows are preserved during a failover.
Supervisor and MSFC Failover Tests
A test environment was created to demonstrate sample
Layer 2 Failover
For Layer 2 traffic between two end stations within the same VLAN , the failover resulted in a one or two ping timeout (approximately one- or
Note: This test can be performed on a supervisor engine without an MSFC.
Layer 3 Failover
For Layer 3 traffic, a common test environment was created for measuring the supervisor or MSFC failover of a single Cisco Catalyst 6500 Series configured first with DRM and then with SRM. The two pinging devices were placed in separate VLANs. The basic software configuration included enabling the High Availability feature on the Cisco Catalyst OS and then either DRM or SRM redundancy in the Cisco IOS Software on the MSFC2. The complete configurations are shown below.
SRM
hostname SRM
!
redundancy
!
interface Vlan20
ip address 10.20.1.3 255.255.255.0 no ip redirects
!
interface Vlan30
ip address 10.30.1.3 255.255.255.0 no ip redirects
!
end
Cisco Systems, Inc.
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