Interface Configuration Guide 7705 SAR Interfaces
Edition: 01 3HE 11011 AAAC TQZZA 135
3.2.15.4.1 Bidirectional 1+1 APS example
Table 18 outlines the steps that the bidirectional APS process will go through during
a typical automatic switching event. The example is read row by row, from left to right,
to provide the complete process of the bidirectional switching event.
3.2.15.5 Revertive Mode
1+1 APS provides revertive and non-revertive modes; non-revertive mode is the
default option. In revertive mode, the activity is switched back to the working port
after the working line has recovered from a failure (or the manual switch is cleared).
In non-revertive mode, a switch to the protection line is maintained even after the
working line has recovered from a failure (or the manual switch is cleared).
Table 18 1+1 APS for Bidirectional Mode – Actions Taken
Status APS Commands Sent in K1
and K2 Bytes on Protection
Line
Action
B to A A to 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 to 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
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