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Example: Configuring Basic APS Support on Routers

 

Requirements for a Basic APS Support

This example uses the following hardware and software components:

  • Two MX Series, M Series, or T Series routers.

  • Junos OS Release 7.4 or later

Basic APS Overview

Automatic Protection Switching (APS) is used by SONET add/drop multiplexers (ADMs) to protect against circuit failures. The Junos implementation of APS allows you to protect against circuit failures between an ADM and one or more routers, and between multiple interfaces in the same router. When a circuit or router fails, a backup immediately takes over.

To configure APS or MSP, you configure a working and a protect circuit, as shown in Figure 1. To protect against a router failure, you connect two routers to the ADM, configuring one of them as the working router and the second as the protect router. To protect against a PIC or FPC failure, you connect one router to the ADM through both the working and protect circuits, configuring one of the PICs or FPCs as the working circuit and the second as the protect circuit.

Figure 1: APS/MSP Configuration Topologies
APS/MSP Configuration Topologies
Note

For SDH interfaces, the Junos OS supports multiplex section protection (MSP). You configure MSP with the same CLI statements you use to configure APS.

Configuring Basic APS Support on Routers

To configure Router A to be the working router and Router B to be the protect router as shown in Figure 1.

On Router A (the Working Router)

Step-by-Step Procedure

Configure basic APS support on Router A as the working router.

  1. In configuration mode, go to the [edit interfaces interface-name sonet-options] hierarchy level, where the interface is so-6/1/1.
  2. Configure the working-circuit option as San-Jose
  3. Configure the authentication-key option as “ $ABC123”

On Router B (the Protect Circuit)

Step-by-Step Procedure

Configure basic APS support on Router B as the protect router.

  1. In configuration mode, go to the [edit interfaces interface-name sonet-options] hierarchy level, where the interface is so-0/0/0.
  2. Configure the protect-circuit option as San-Jose
  3. Configure the authentication-key option as “ $9$B2612345”
  4. Configure the neighbor option as 192.168.1.2 that is the address of Router A on the link between A and B.

On a Single Platform, One Interface as the Working Circuit and Another Interface as the Protect Circuit

Step-by-Step Procedure

Configure one interface as the working circuit.

  1. In configuration mode, go to the [edit interfaces interface-name sonet-options] hierarchy level, where the interface is so-2/1/1 .
  2. Configure the working-circuit option as Bayward
  3. Configure the authentication-key option as blarney

Step-by-Step Procedure

Configure one interface as the protect circuit.

  1. In configuration mode, go to the [edit interfaces interface-name sonet-options] hierarchy level, where the interface is so-3/0/2.
  2. Configure the working-circuit option as Bayward
  3. Configure the authentication-key option as blarney

Results

Display the results of the configuration.

On Router A (the Working Router)

On Router B (the Protect Circuit)

On a Single Platform, One Interface as the Working Circuit and Another Interface as the Protect Circuit

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