ETH-CFM (802.1ag and Y.1731)
Page 74 7705 SAR OS Services Guide
The specific configuration information required by a MEP to support the ETH-RDI function
is as follows:
• MEG level — the MEG level at which the MEP exists
• ETH-RDI transmission period — application-dependent and is the same value as the
ETH-CC transmission period
• priority — the priority of frames containing ETH-RDI information and is the same
value as the ETH-CC priority
The PDU used to carry ETH-RDI information is the CCM.
ETH-AIS
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
MEP.
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. Once the AIS condition is cleared, a MEP resumes alarm generation upon
detecting defect conditions.
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