Bidirectional 1+1 switchover operation example

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

Table: Actions for the bidirectional 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