AIS operates independently from the low-priority-defect setting. The low-priority-defect setting configuration parameter affects only the ETH-CFM fault propagation and alarming outside the scope of AIS. Any fault in the MEP state machine generates AIS when it is configured. The following table describes the ETH-CC defect condition groups, configured low-priority-defect setting, priority, and defect as it applies to fault propagation.
| Defect | Low priority defect | Description | Causes | Priority |
|---|---|---|---|---|
DefNone |
N/A |
No faults in the association |
Normal operations |
N/A |
DefRDICCM |
allDef |
Remote Defect Indication |
Feedback mechanism to inform that unidirectional faults exist. It provides the feedback loop to the node with the unidirectional failure conditions. |
1 |
DefMACStatus (default) |
macRemErrXcon |
MAC Layer |
Remote MEP is indicating that a remote port or interface is not operational. |
2 |
DefRemoteCCM |
remErrXon |
No communication from remote peer |
MEP is not receiving CCM from a configured peer. The timeout of CCM occurs at 3.5 times the local CC interval. As per the specification, this value is not configurable. |
3 |
DefErrorCCM |
errXcon |
Remote and local configurations do not match required parameters |
Caused by different interval timer, domain-level issues (lower value arriving at a MEP configured with a higher value), MEP receiving CCM with its MEPID |
4 |
DefXconn |
Xcon |
Cross Connected Service |
The service is receiving CCM packets from a different association. This could indicate that two services have merged or there is a configuration error on one of the SAPs or bindings of the service, incorrect association identification. |
5 |