Line Modules - Juniper ERX - RELEASE 11.1.X HARDWARE GUIDE 03-23-2010 Hardware Manual

ERX 11.1.x Hardware Guide

Line Modules

NOTE: This section applies to ERX7xx and ERX14xx models only. ERX310 routers
do not offer line module redundancy.
ERX7xx and ERX14xx models support line module redundancy for several line
modules. For details about which line modules support redundancy, see the ERX
Module Guide. In this scheme, an extra line module in a group of identical line modules
provides redundancy in case of line module failure. To use this feature, you need a:
A redundancy midplane can cover 3–6 slots. It provides additional connectivity that
enables the spare line module to take control of the I/O module associated with any
failed line module in the redundancy group. The spare I/O module provides
connectivity from the spare line module to the redundancy midplane.
The process by which the system switches to the spare line module is called
switchover. When switchover occurs, the system:
1.
2.
Protocol processing then takes place on the spare line module.
Figure 12 on page 17 shows the data flow when a spare line module becomes active.
16
Redundancy Features
Spare line module
Redundancy midplane
Redundancy I/O module
Breaks the connection between the primary I/O module and the primary line
module.
Connects the primary I/O module to the spare line module via the redundancy
midplane and redundancy I/O module.