# Managing Port Redundancy on Gigabit Ethernet I/O Modules

By default, the software manages port redundancy on Gigabit Ethernet I/O modules automatically. However, you can manage redundancy on GE I/O modules as follows:

- Specify the time that the router waits for a port on a Gigabit Ethernet I/O module to become active before the router switches to the redundant port.
- Force a Gigabit Ethernet I/O module to switch operation from one port to the other.
- Disable port redundancy by specifying operation on one port only.
- Clear Address Resolution Protocol (ARP) entries on interfaces with redundant ports when the primary link fails.

If you manage port redundancy manually, the router retains the manual configuration after the module reboots.

You can monitor the port redundancy configuration with the show interfaces gigabitEthernet command and the show interfaces tenGigabitEthernet command.

| Note: The router manages failover in the same way for the Gigabit Ethernet I/O modules and the GE-2 SFP I/O module.

link failover arp-flush

- Use to clear the ARP cache on an interface with redundant ports when the primary link fails. This feature enables the router to clear the ARP entries and obtain the media access control (MAC) address of the active link, thereby reducing the delay in learning new MAC addresses.
- Clearing the ARP cache after a link failover is supported on GE I/O modules with redundant ports.
- Example
  host1(config)#interface gigabitEthernet 1/0 host1(config-if)#link failover arp-flush
- Use the no version to maintain the ARP entries on the interface in the event of a failover.
- See link failover arp-flush.

link failover force

- Use to force a Gigabit Ethernet I/O module to switch operation from one port to the other.
- Select an interface on the Gigabit Ethernet I/O module before you issue this command.
- Example
  host1(config)#interface gigabitEthernet 5/0 host1(config-if)#link failover force
- There is no no version.
- See link failover force.

link failover timeout

- Use to specify the time that the router waits for a port on a GE I/O module to become active before the router switches to the redundant port.
- Select an interface on the GE I/O module before you issue this command.
- Specify a time in the range 100–10,000 ms.
- Example
  host1(config)#interface gigabitEthernet 5/0 host1(config-if)#link failover timeout 1000
- Use the no version to restore the default situation in which the router sets this time automatically.
- See link failover timeout.

link selection

- Use to disable redundancy on a GE I/O module by allowing operation on the specified port only.
- Select an interface on the GE I/O module before you issue this command.
- Example
  host1(config)#interface gigabitEthernet 5/0 host1(config-if)#link selection secondary
- Use the no version to restore the default situation in which port redundancy is enabled.
- See link selection.