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Junos Security by James Quinn, Timothy Eberhard, Patricio Giecco, Brad Woodberg, Rob Cameron

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Fault Monitoring

“In the event of a failure, your seat cushion may be used as a flotation device.” If your plane were to crash and you were given notice, you would take the appropriate action to prevent disaster. When working with a chassis cluster, an administrator wants to see the smoke before the fire. That is what happens when an administrator configures monitoring options in the chassis cluster. The admin is looking to see if the plane is going down and to take evasive action before it’s too late. By default, the SRX monitors for various internal failures such as hardware and software issues. But what if other events occur, such as interfaces failing, or upstream gateways going away? If the administrator wants to take action based on these events, he must configure the SRX to take action.

The SRX monitoring options are configured on a per-redundancy-group basis, meaning that if specific items were to fail, that redundancy group can fail over to the other chassis. In complex topologies, this gives the administrator extremely flexible options on what to fail over and when. Two integrated features can be used to monitor the redundancy groups: interface monitoring and IP monitoring.

And there are two situations the SRXs can be in when a failure occurs. The first is that the SRXs are communicating and the two nodes in the cluster are both functional. If this is the case, and a failure occurs, the failover between the two nodes will be extremely fast because the two nodes can quickly ...

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