Chapter 26 Configuring Sonet Automatic Protection System; Introduction - Cisco BPX-BXM-155-8DX Installation And Configuration Manual

Configuring SONET Automatic Protection
System
This chapter contains a description and configuration information for the SONET Automatic Protection
System (APS) which may be used to provide line and card redundancy for BXM OC-3 and OC-12 cards:
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The APS alarms are listed in Chapter 28, Alarms and Statistics.
Refer to the Cisco WAN Switch Command Reference for further information on configuration and
monitoring commands.
To troubleshoot the APS configuration and operations, see Chapter 29, Troubleshooting.

Introduction

Automatic Protection Switching (APS) configures a pair of SONET lines for line redundancy so that
hardware automatically switches from a Working line to a Protection line when the Working line fails,
and vice versa, within a specified period after an active line failure.
Each redundant line pair consists of a Working Line and a Protection Line. The concept of Working and
Protection Lines is similar to the concept of Primary and Secondary Y Redundant cards. That is, the
Working line is the logical line to which the user refers.
Left undisturbed, hardware performs line switching automatically. Upon detection of a Signal Fail
condition (LOS, LOF, Line AIS or Bit Error Rate exceeding a configured limit) or a Signal Degrade
condition (BER exceeding a configured limit), hardware switches from the Working Line to the
Protection Line (assuming the Working line was the Active line and the Protection line is not in alarm).
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
Introduction
Tiered Management Control
Operation Criteria
APS 1+1 (Card and Line Redundancy)
APS 1:1 (Line Redundancy)
APS 1 +1 Annex B Card and Line Redundancy
Test Loops
Notes on APS Messages
APS K1 Command Precedence
APS Command Summary
C H A P T E R
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