# Installing Components for Line Module Redundancy

A spare line module provides redundancy for a group of identical line modules for ERX7xx and ERX14xx models only.

| Note: The ERX310 router does not support line module redundancy.

For line module redundancy to operate, you must install:

- The line modules, including the spare line module
- The redundancy midplane
- The I/O modules, including the spare I/O module

For more information, see Redundancy Features.

| Warning: Do not insert any metal object, such as a screwdriver, or place your hand into an open slot or the backplane when the router is on. Remove jewelry (including rings, necklaces, and watches) before working on equipment that is connected to power lines. These actions can prevent electric shock and serious burns.

| Caution: When handling modules, use an antistatic wrist strap connected to the router's ESD grounding jack, and hold modules by their edges. Do not touch the components, pins, leads, or solder connections. These actions help to protect modules from damage by electrostatic discharge.

## Installing the Line Modules

To install the line modules in a redundancy group:

1. Install the spare line module in the lowest-numbered slot of the redundancy group.
2. Install the other line modules in the remaining slots. (See Installing Line and I/O Modules.)

## Installing the Redundancy Midplane

To install the redundancy midplane in a redundancy group:

| Caution: If you do not use the halt command before removing or powering down an SRP, the system's NVS card can become corrupted.

1. Enter the halt command.

   See JunosE System Basics Configuration Guide, Chapter 6, Managing Modules for information about the halt command.

   | Warning: Turn off the router before you install the redundancy midplane. Working inside the router when it is on can lead to electric shock and serious burns.

2. Turn off the power switches located on the power input module in the rear of the system (Figure 22).
3. Remove the I/O modules from the slots that the redundancy midplane will span.
4. Place the redundancy midplane in the chassis so that it rests against the guides below the chassis midplane (Figure 22).
5. Align the screw holes in the redundancy midplane with the screw holes in the guides so that the midplane covers the slots for the redundancy group.
6. Using a No. 2 Phillips screwdriver and the screws provided, loosely attach, but do not tighten, the redundancy midplane to the guides.
7. Carefully insert an I/O module in one slot to ensure that the redundancy midplane is aligned correctly; then tighten the screws.

   | Caution: Do not overtighten the screws.

   | Caution: A misaligned redundancy midplane can result in bent pins on the backplane and midplane and poor contact between the I/O modules and the redundancy midplane.

   Figure 22: Installing a Redundancy Midplane

## Installing the I/O Modules

To install the I/O modules in a redundancy group:

1. Install the redundancy I/O module in the lowest-numbered slot of the redundancy group.

   | Caution: When setting up a redundancy group with line modules, be sure to install the redundancy I/O module in the lowest-numbered slot of the redundancy group. It is possible to install the redundancy I/O module in other slots; however, doing so can damage other I/O modules connected to the redundancy midplane.

2. Install the corresponding I/O module for the line module of each slot in the redundancy group. (See Installing a Line Module or an I/O Module.)
3. Cable each module to provide a path to the remote interface. (See Cabling ERX Routers.)

## Verifying the Installation

To verify that the installation is complete:

1. After you have cabled the system for power, as described in Cabling ERX Routers, turn on the power switches.

   The system reboots.

2. Issue the show redundancy command, and verify that the display shows the redundancy hardware.