Alcatel-Lucent 7750 Configuration Manual page 83

APS Channel Mismatch Failure
An APS channel mismatch failure (APS-CM) identifies that there is a channel mismatch between
the transmitted K1 and the received K2 bytes. A defect is declared when the received K2 channel
number differs from the transmitted K1 channel number for more than 50 ms after three identical
K1 bytes are sent. The monitoring for this condition is continuous, not just when the transmitted
value of K1 changes.
If the failure detected persists for 2.5 seconds, a channel mismatch failure alarm is raised. When
the failure is absent for 10 seconds, the alarm is cleared. This alarm can only be raised by the
active port operating in a bi-directional mode.
APS Mode Mismatch Failure
An APS mode mismatch failure (APS-MM) can occur for two reasons. The first is if the received
K2 byte indicates that 1:N protection switching is being used by the far-end of the OC-N line,
while the near end uses 1+1 protection switching. The second is if the received K2 byte indicates
that uni-directional mode is being used by the far-end while the near-end uses bi-directional mode.
This defect is detected within 100 ms of receiving a K2 byte that indicates either of these
conditions. If the failure detected persists for 2.5 seconds, a mode mismatch failure alarm is raised.
However, it continues to monitor the received K2 byte, and should it ever indicate that the far-end
has switched to a bi-directional mode the mode mismatch failure clearing process starts. When the
failure is absent for 10 seconds, the alarm is cleared, and the configured mode of 1+1 bidirectional
is used.
APS Far-End Protection Line Failure
An APS far-end protection line (APS-FEPL) failure corresponds to the receipt of a K1 byte in 3
consecutive frames that indicates a signal fail (SF) at the far end of the protection line. This forces
the received signal to be selected from the working line.
If the failure detected persists for 2.5 seconds, a far-end protection line failure alarm is raised.
When the failure is absent for 10 seconds, the alarm is cleared. This alarm can only be raised by
the active port operating in a bi-directional mode.
7750 SR Interface Configuration Guide
Interface Configuration
Page 83