Differences between 802.1ag and Y.1731

Differences between SOAM IEEE 802.1ag and Y1731 standards:

• Continuity Check Protocol

1. No MD (Mainttanance Domain) field in Y.1731 CCM messages. MEG name in Y.1731 and MA name in 802.1ag have different formats.
2. Sequence Number field  in Y.1731 is set to all-ZEROes as against 802.1ag CCM Sequence Number field should be incremented with every CCM transmitted. It is used to count the total number of out-of-sequence CCMs received on 802.1ag MEPs.
3. There no TxFCf,  TxFCb,  RxFCb counters in 802.1ag CCM messages: they are used for performance monitoring in Y.1731 standard.
4. There cannot be Sender ID, Port Status and Interface Status TLVs in Y.1731 CCM messages. 

•  Linktrace

1.  LTM/LTR message in 802.1ag mode can include optional Sender ID and Organization-Specific TLVs.
2.  Relay Action field is reserved in Y.1731 LTR messages. In 802.1ag it reports how the data frame  targeted by the LTM would be passed through the MAC Relay Entity to the Egress Bridge Port.
3. The following fields of LTR Ingress/Egress TLVs are reserved in Y.1731:  Ingress action,  Ingress MAC address,  Egress action,  Egress MAC address.

•   AIS (Alarm indication signal): there no AIS frames/notifications in 802.1ag at all.
•   802.1ag standart does not include a stack of performance monitoring protocols (Delay Measurement, Frame Loss Measurement, Throughput Measurement) as well as Ethernet Locked, Ethernet Test, Ethernet Automatic protection switching, Ethernet maintanance communication, Ethernet experimental OAM and Ethernet Vendor-Specific OAM.

Defects correlation 

                                         Y.1731                                   802.1ag

                             Loss of continuity (LOC)...............RemoteCCM

                             Mismerge....................................XconnCCM

                             Unexpected MEP.........................ErrorCCM

                             Unexpected MEG........................XconnCCM

                             Unexpected period.......................ErrorCCM

                             Signal fail....................................no correlation

                             AIS.............................................no such defect

                             RDI.............................................RDICCM

                             LCK............................................no such defect

So, the MEPs and MIPs working in one mode (802.1ag for example) would asnwer to Loopback and Linktrace requests from the MEPs working in Y.1731 mode. But it will be always XconnCCM (Unexpected MEG) present on the MEPs working in different modes.