Conditions That Trigger a Routing Engine Failover

The following events can result in an automatic change in Routing Engine mastership, depending on your configuration:

• The routing platform experiences a hardware failure. A change in Routing Engine mastership occurs if either the Routing Engine or the associated host module or subsystem is abruptly powered off. You can also configure the backup Routing Engine to take mastership if it detects a hard disk error on the master Routing Engine. To enable this feature, include the failover on-disk-failure statement at the [edit chassis redundancy] hierarchy level.
• The routing platform experiences a software failure, such as a kernel crash or a CPU lock. You must configure the backup Routing Engine to take mastership when it detects a loss of keepalive signal. To enable this failover method, include the failover on-loss-of-keepalives statement at the [edit chassis redundancy] hierarchy level.
• A specific software process fails. You can configure the backup Routing Engine to take mastership when one or more specified processes fail at least four times within 30 seconds. Include the failover other-routing-engine statement at the [edit system processes process-name] hierarchy level.

If any of these conditions is met, a message is logged and the backup Routing Engine attempts to take mastership. By default, an alarm is generated when the backup Routing Engine becomes active. After the backup Routing Engine takes mastership, it continues to function as master even after the originally configured master Routing Engine has successfully resumed operation. You must manually restore it to its previous backup status. (However, if at any time one of the Routing Engines is not present, the other Routing Engine becomes master automatically, regardless of how redundancy is configured.)

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