# Configuring Ethernet Link Redundancy

To configure Ethernet link redundancy:

1. Specify the Fast Ethernet or Gigabit Ethernet interface on which to configure a redundant link.
   host1(config)#interface gigabitEthernet 1/1
2. For LAG to non-LAG configurations only, specify that LACP is disabled on the port.
   host1(config-if)#no lacp
3. Configure a backup interface and disable LACP on it.
   host1(config)#interface gigabitEthernet 1/0 host1(config-if)#no lacp
4. Configure a LAG interface and assign a member link to the backup interface.
   host1(config)#interface lag myBundle host1(config-if)#member-interface gigabitEthernet 1/0 host1(config-if)#member-interface gigabitEthernet 1/1
5. Do one of the following:
   - Configure link redundancy on the port you specified in step 1.
     host1(config-if)#redundant-port gigabitEthernet 1/1
   - Force the port you specified in step 1 to fail over.
     host1(config-if)#redundant-port gigabitEthernet 1/1 force-failover
6. (Optional) Configure the redundant link to revert back to redundant mode when the failed link becomes active again.
   host1(config-if)#redundant-port gigabitEthernet 1/1 auto-revert

redundant-port

- Use to specify a member link in a LAG bundle as redundant.
- Use the failover timeout keyword to configure the amount of time between the current link event leading to failover or reversion and the previous link failover or reversion. The default value is 1000 milliseconds.
- Use the packet-sampling keyword to configure redundancy on a LAG to non-LAG application where packet sampling is used for failover detection. By default, packet sampling is disabled. Use the optional delay keyword to control the minimum time difference to force packets on the active and redundant port to fail over. The default value is 0 milliseconds.
- Use the transmitter keyword to enable or disable the transmitter when in redundant mode.
  - Disabling the transmitter enables the remote end of the redundant link to also be in the operational Down state, which might be a requirement for third-party equipment when supporting redundancy over LAG.
  - Enabling the transmitter provides for a quick LAG failover in the event one of the non-redundant links in the LAG fail. This is particularly true when LACP has been enabled on the LAG, because it can take several seconds for LACP to converge on a link.
- Use the auto-revert keyword to instruct the redundant link to revert back to redundant mode when the failed link becomes active again. By default, auto-revert is disabled.
- Example 1—Specifies that the Gigabit Ethernet interface in slot 4, port 0 is a redundant member interface
  host1(config-if)#redundant-port gigabitEthernet 4/0
- Example 2—Specifies that the Gigabit Ethernet interface in slot 1, port 1 is a redundant member interface with a packet sampling delay of 500 ms
  host1(config-if)#redundant-port gigabitEthernet 1/1 packet-sampling delay 500
- Use the no version to disable the redundant status of the member interface or disable the specified redundancy setting for the member.
- See redundant-port.

redundant-port force-failover

- Use to force the specified member interface to fail over when more than one active member exists.
- Example
  host1(config-if)#redundant-port gigabitEthernet 4/0 force-failover
- There is no no version.
- See redundant-port force-failover.