Cisco ASR 900 Series Configuration Guide

• Revertive option — For any failure on working line, the software switches to protection line and when
the working line recovers, it waits based on the revertive timer and reverts back to working line as active
link.
• Non-revertive option — When the signal fails, the software switches to the protection line and does not
automatically revert back to the working line. This is the default option.
The following features are supported on 1+1 APS:
•
SONET PW (SAToP or CEP)
•
SONET local connect
Benefits of APS
The following lists the benefits of APS:
•
APS performs switchovers with minimal loss of data and time-consuming reroutes are avoided.
•
There is no visibility that a failure has occurred beyond the network element in which it is residing; other
nodes are not affected by the failure.
•
Implementation of APS guards a network against complex restarts and resynchronizations since failures
are isolated to a local device.
•
With APS, the effect of a failure is greatly minimized and a fast switchover guarantees minimal effect
on the network.
APS 1+1 for SONET Layer 1 traffic
SONET linear APS 1+1 provides protection against both fiber cuts and front card or back card failures. APS
1+1 requires a redundant protection line for every working line. The traffic is simultaneously carried by the
working and the protection lines. Hence, the receiver that terminates the APS 1+1 should select the traffic
from one of the lines and continue to forward the traffic. APS 1+1 provides protection in unidirectional and
bi-directional modes:
•
Uni-directional Protection: The receiving end can switch from working to protection line without any
coordination at the transmit end since both lines transmit the same information.
•
Bi-directional Protection: The receiving end switches from working to protection line by coordinating
at the transmit end.
1-Port OC-192 or 8-Port Low Rate CEM Interface Module Configuration Guide, Cisco IOS XE Everest 16.7.x (Cisco
ASR 900 Series)
29
Configuring SONET
1+1 APS

Cisco ASR 900 Series Specifications

General

Brand	Cisco
Model	ASR 900 Series
Category	Network Router
Language	English