Technical Documentation

Configuring FEB Redundancy on the M120 Router

To configure a FEB redundancy group for the M120 router, include the following statements at the [edit chassis redundancy feb] hierarchy level:

[edit chassis redundancy feb]redundancy-group group-name {description description;feb slot-number (backup | primary);no-auto-failover;}

group-name is the unique name for the redundancy group. The maximum length is 39 alphanumeric characters.

slot-number is the slot number of each FEB you want to include in the redundancy group. The range is from 0 through 5. You must specify exactly one FEB as a backup FEB per redundancy group. Include the backup keyword when configuring the backup FEB and make sure that the FEB is not connected to an FPC.

Include the primary keyword to optionally specify one primary FEB per redundancy group. When the primary keyword is specified for a particular FEB, that FEB is configured for 1:1 redundancy. With 1:1 redundancy, the backup FEB contains the same forwarding state as the primary FEB. When no FEB in the redundancy group is configured as a primary FEB, the redundancy group is configured for n:1 redundancy. In this case, the backup FEB has no forwarding state. When a FEB fails, the forwarding state must be downloaded from the Routing Engine to the backup FEB before forwarding continues.

A combination of 1:1 and n:1 redundancy is possible when more than two FEBs are present in a group. The backup FEB contains the same forwarding state as the primary FEB, so that when the primary FEB fails, 1:1 failover is in effect. When a nonprimary FEB fails, the backup FEB must be rebooted so that the forwarding state from the nonprimary FEB is installed on the backup FEB before it can continue forwarding.

You can optionally include the description statement to describe a redundancy group.

Automatic failover is enabled by default. To disable automatic failover, include the no-auto-failover statement. If you disable automatic failover, you can perform only a manual switchover using the operational command request chassis redundancy feb slot slot-number switch-to-backup.

To view FEB status, issue the show chassis feb command. For more information, see the JUNOS System Basics and Services Command Reference.


Published: 2010-04-28