T320 Router and T640 Routing Node Routing Engine Redundancy
Figure 197 shows the T320 router redundant Routing Engines that are components of the host subsystem.
Figure 198 shows the T640 routing node redundant Routing Engines that are components of the host subsystem.
The host subsystem consists of a Routing Engine and a Control Board. You can install two host subsystems in the T320 router and T640 routing node. For more information about monitoring redundant Control Boards, see Monitoring Redundant Control Boards.
Both the Routing Engine and the Control Board must be installed for the host subsystem to function. When two host subsystems are installed in the router, both are powered on, but only one is the master; the second host subsystem is the backup and performs no functions. By default, the master host subsystem has components installed in slots RE0 and CB0; the backup host module has components installed in slots RE1 and CB1. If one Routing Engine physically fails, the other one assumes the routing functions. If a software failure occurs, the other backup Routing Engine assumes routing functions if some preliminary configuration has been done. For more information, seeHost Redundancy Overview.
The T320 router and T640 routing node craft interface LEDs indicate the Routing Engine operating status and mastership. (See Check the T320 Router Routing Engine LEDs and Check the T640 Routing Node Routing Engine LEDs.)