Redundancy Connection for an M320 Router
Figure 190 shows the connection between the master and backup host subsystems on an M320 router. Keepalive messages are sent from the Routing Engine over the em0 interface. The keepalive message is forwarded to the other host subsystem via the bcm0 interface on the Control Board. A keepalive response is sent back over the em0 interface to the other Routing Engine. In this way, the master and the backup host subsystems exchange state information.
