M320 Control Board (CB) Description
Each CB works with an adjacent Routing Engine to provide control and monitoring functions for the router (see Figure 1). These functions include determining Routing Engine mastership, controlling power and reset for the other router components, monitoring and controlling fan speed, and monitoring system status.
You can install one or two CBs in the router. They install into the upper rear of the chassis in the slots labeled CB0 and CB1 (referred to as CB-0 and CB-1, top to bottom) (referred to as CB-0 and CB-1, top to bottom). If two CBs are installed, one functions as the master CB and the other as its backup. If the master fails or is removed, the backup restarts and becomes the master.
Each CB requires a Routing Engine to be installed in the adjacent slot. CB0 installs above RE0, and CB1 installs below RE1. A CB cannot function if a Routing Engine is not present in the adjacent slot.
CBs are hot-pluggable.
Figure 1: CB
