Bidirectional 1+1 Switchover Operation Example

Table 1 describes the steps that a bidirectional protection switching process goes through during a typical automatic switchover.

Table 1. Actions for the Bi-directional Protection Switching Process

Status

APS Commands Sent in K1 and K2 Bytes on Protection Line

Action

B -> A

A -> B

At Site B

At Site A

No failure (Protection line is not in use).

No request

No request

No action

No action

Working line Degraded in direction A->B.

SD on working channel 1

No request

Failure detected, notify A and switch to protection line

No action

Site A receives SD failure condition.

Same

Reverse request

No action

Remote failure detected, acknowledge and switch to protection line

Site B receives Reverse request.

Same

Same

No action

No action