Understanding the Host Module
Purpose
Inspect the host module to ensure that the Routing Engine and Miscellaneous Control Subsystem (MCS) function properly.
What Is a Host Module
The host module is present on M40e and M160 routers. The host module constructs routing tables, performs system management functions, and generates the SONET/SDH clock signal for SONET/SDH interfaces.
The host module is comprised of two components: the Routing Engine and the MCS. For a host module to function, both of these components must be installed and operational.
Figure 140 shows the Routing Engine component of the host module.
Figure 141 shows the MCS component of the host module.
One or two host modules can be installed into the midplane from the rear of the chassis (see Figure 142). The Routing Engine (slot RE0) is below the MCS slot (MCS0), while slot RE1 is above the MCS1 slot. RE0 must use MCS0 and RE1 must use MCS1 or the circuit will not be connected.
This chapter provides basic information about monitoring the Routing Engine and the MCS. For more detailed information about monitoring the Routing Engine, see Monitoring the Routing Engine. For more detailed information about monitoring the MCS, see Monitoring the MCS.