The Ethernet Alarm Indication Signal function (ETH-AIS) is a Y.1731 CFM enhancement used to suppress alarms at the client (sub) layer following detection of defect conditions at the server (sub) layer.
Transmission of frames with ETH-AIS information can be enabled or disabled on a Y.1731 SAP MEP.
ETH-AIS is enabled using the eth-cfm>mep>ais-enable command for Epipe and VPLS services.
ETH-AIS is not supported on network interface facility MEPs.
Frames with ETH-AIS information can be issued at the client MEG level by a MEP, including a server MEP, upon detecting the following conditions:
signal failure conditions in the case where ETH-CC is enabled
AIS condition in the case where ETH-CC is disabled
For a point-to-point Ethernet connection at the client (sub) layer, a client layer MEP can determine that the server (sub) layer entity providing connectivity to its peer MEP has encountered a defect condition upon receiving a frame with ETH-AIS information. Alarm suppression is simplified by the fact that a MEP is expected to suppress only those defect conditions associated with its peer MEP.
Only a MEP, including a server MEP, is configured to issue frames with ETH-AIS information. Upon detecting a defect condition, the MEP can immediately start transmitting periodic frames with ETH-AIS information at a configured client MEG level. A MEP continues to transmit periodic frames with ETH-AIS information until the defect condition is removed. Upon receiving a frame with ETH-AIS information from its server (sub) layer, a client (sub) layer MEP detects the AIS condition and suppresses alarms associated with all its peer MEPs. After the AIS condition is cleared, a MEP resumes alarm generation upon detecting defect conditions.
The following specific configuration information is required by a SAP MEP to support ETH-AIS:
client MEG level — the MEG level at which the most immediate client layer MEPs exist
ETH-AIS transmission period — the transmission period of frames with ETH-AIS information
priority — the priority of frames with ETH-AIS information