Understanding Redundancy for the Routing Engine, Host Module, and Host Subsystem

Purpose

To learn how redundant Routing Engines, host modules, and host subsystems work on various routing platforms. You monitor these components to provide a standby Routing Engine and controller component that will switch from standby to active, assuming mastership when a failure brings down the active master Routing Engine.

What Is a Routing Engine, Host Module, and Host Subsystem Redundancy

Redundant Routing Engines are two Routing Engines that are installed in the same routing platform. One functions as the master, while the other stands by as a backup should the master Routing Engine fail. (See M10i Router Redundant Routing Engines and HCMs and M20 Router Redundant Routing Engines and SSBs.)

Redundant host modules are two Routing Engine and Miscellaneous Control Subsystem (MCS) pairs installed in the same routing platform. One pair functions as master, while the other stands by as a backup should the master Routing Engine fail. (See M40e and M160 Router Redundant Host Modules.)

Redundant host subsystems are two Routing Engine and Control Board pairs installed in the same routing platform. One pair functions as master, while the other stands by as backup should the master Routing Engine fail. (See M320 Router, T320 Router, and T640 Routing Node Redundant Host Subsystems.)

The M5, M10, M7i, and M40 routers do not support Routing Engine, host module, or host subsystem redundancy.