Technical data

N+1 Redundancy

Configure Redundant Ethernet Failover With the CLI

The following commands configure Ethernet interface 2 on a controller as a backup

to Ethernet interface 1. Do this by issuing the option redundant for the type

command as shown below.

default# configure terminal

default(config)# interface FastEthernet 2

default(config-if-FastEth)# type redundant

default(config-if-FastEth)# exit

default(config)# exit

default(config)# copy running-config startup-config

The system requires a reboot for the change to become effective. Reboot the system

now, and then check the redundant second interface configuration with the show

second_interface_status command:

default# show second_interface_status

Recovering From Redundant Ethernet Failover

Once Dual Ethernet Redundant mode configuration is complete, the controller needs

to be rebooted - see directions above. After the reboot, if the first Ethernet interface

link goes down, then the second Ethernet interface takes over the controller connec-

tivity. Redundant Ethernet failover is based on LinkID and does not require any span-

ning-tree configuration. When a LinkID is missing, the failover will occur in under one

second. This failover will be transparent to the access points. The second interface

remains active and serving all APs, even if the first interface comes up again. Verify

this with the CLI command show second-interface-status. Only when the second

interface goes down will the first interface (if it is up) take over the controller

connectivity.

When N+1 or L3 redundancy is also configured and controller 1 fails, the APs move to

controller 2. When controller 1 comes back online, the APs immediately begin to

move back to controller 2. Also see Recovering From N+1 with Dual Ethernet Failover.

N+1 Redundancy

The optional N+1 redundancy software feature, when implemented, allows a standby

N+1 slave controller in the same subnet to monitor and failover more than one master

controller.

Note:

In the redundant configuration, the IP address for the second Ethernet

interface cannot be configured. It will receive the IP address of the primary Ethernet

interface when the failover occurs.