Redundancy Connection for an M40e or M160 Router
Figure 189 shows the connection between the master and backup host modules on an M40e or M160 router. Keepalive messages are sent from one Routing Engine to the other over the fpx2 interface found across the Peripheral Component Interconnect (PCI) bridge. The keepalive message is received by the other host module via the fpx1 interface. A keepalive response is sent back over the fpx2 interface to the other Routing Engine. In this way, the master and the backup host modules exchange state information.
