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Figure 286: TX Matrix and TX Matrix Plus Router Redundant Host

Subsystems

g006596

TX-CB-1

TX-CB-0

TX Matrix

TX Matrix Plus

Routing

Engines

CB 0

CB 1

RE 0

RE 1

Documentation

Routing Engine, Host Module, and Host Subsystem Redundancy Connections

It is important to understand how a redundant Routing Engine, redundant host module,

or redundant subsystem communicates with its active counterparts to avoid severing

the connection used for communication. Severing the connection can potentially trigger

a failover protection.

For example, the M160 router active host module (the Routing Engine and the MCS) has

the running configuration on it and communicates with the MCS, which in turn

communicates with the Flexible PIC Concentrator (FPC) and the Switching and

Forwarding Modules (SFMs). The host modules send keepalive messages to each other,

checking the operating state. Each host module issues keepalive responses, letting the

other host module know that it is up and operating. If keepalive responses are not returned

to the standby host module (response times will vary depending upon the time settings

specified in the set chassis redundancy keepalive-time statement), the standby host

module can become the active host module.

You also can configure failover on the router to switch mastership if a critical process

fails. If a critical process on the active host module terminates, the standby host module

routing becomes the active host module. You can configure processes for which this

M Series and T Series Routers Monitoring and Troubleshooting Guide

Juniper M Series User Manual

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