ETH-CFM (802.1ag and Y.1731)
Page 62 7705 SAR OS Services Guide
MDs, MD Levels, MAs, and MEPs (802.1ag)
Maintenance domains (MDs) and maintenance associations (MAs) are configured at the
global level. Maintenance association endpoints (MEPs) are configured at the service level.
An MD is a set of network elements that have a common CFM OAM purpose. MDs are
identified by their MD index and can be given an MD name. An MD is assigned a
maintenance domain level (MD level). There are eight MD levels. Use MD levels to set up a
messaging hierarchy for the CFM architecture.
An MA consists of a pair of maintenance endpoints (one local and one remote MEP) that are
managed as part of an Ethernet VLL service. The MA and the VLL service are associated by
configuring the MA’s bridge identifier parameter to have the same value as the VLL service
ID parameter of the VLL service that supports the MEP. MAs are identified by their MA
index and can be given an MA name. The MA is used to verify the integrity of a single
service instance.
A MEP is configured as part of an Ethernet SAP or spoke SDP. MEPs can generate or
terminate CFM OAM messages. MEPs only communicate within the same MD level, where
the value of the MD level (0 to 7) is carried in a CFM OAMPDU. MEPs are identified by
their MEP identifier and MA-ID. The MA-ID is configured at the global level.
Figure 9 depicts a high-level view of MEPs in a CFM-enabled network. Two MAs are
shown. The endpoints of MA 1 are MEPs 1 and 2, while MEPs 3 and 4 are the endpoints for
MA 2.
For more information on MEP support on Ethernet SAPs and spoke SDPs, see Ethernet
OAM on page 161.
Table 9: Y.1731 Terminology
Term Expansion Definition
MEG Maintenance Entity Group Same as MA but applies to Y.1731
MEG-ID Maintenance Entity Group
Identifier
Same as MA-ID but applies to Y.1731
MEG
level
Maintenance Entity Group
Level
Same as MD level but applies to Y.1731
Note that although MEG level and MD level are equivalent terms,
there is no Y.1731 equivalent to an MD
MEP Maintenance Association
End Point
Same as MEP for 802.1ag
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