Juniper Networks 8 manual Shows the data flow when a spare line module becomes active

ERX 8.0.x Hardware Guide

of identical line modules provides redundancy in case of line module failure. To use this feature, you need a:

Spare line module

Redundancy midplane

Redundancy I/O module

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.Breaks the connection between the primary I/O module and the primary line module.

2.Connects the primary I/O module to the spare line module via the redundancy midplane and redundancy I/O module.

Protocol processing then takes place on the spare line module.

Figure 12 shows the data flow when a spare line module becomes active.

18 Redundancy Features