What is CFM?

Connectivity Fault Management

Ethernet Connectivity Fault Management in NSP is implemented based on the IEEE Y.1731 and 802.1ag OAM standards. The standards describe protocols for detecting, isolating, and reporting connectivity faults in an Ethernet network. CFM is a Layer 2 OAM object infrastructure.

You can use Ethernet CFM for the following:

path discovery
fault detection
fault isolation
fault notification

The following table describes terms relevant to CFM in NSP.

Term	Expansion	Notes
MD	Maintenance domain	MD is the administrative container that defines the scope, reach and boundary for CFM message handling. It is typically the area of ownership and management responsibility. MD levels are in the range of 0 to 7, where the larger the domain, the larger the MD level assigned.
MA	Maintenance association	MA is the construct where the different management entities such as MEPs are contained. An MA is created within an MD. There is also an administrative context where a linkage is made between the domain and the service using the MA bridging-identifier configuration option.
MEG	Maintenance entity group	Typically, a MEG represents one service and consists of a group of MEPs. Only one MEG can be associated with a service, but one service can be associated with multiple MEGs. MDs and MEGs are distributed to NEs using policy distribution.
MEP	Maintenance end point	MEPs are the entities at the edge of a CFM MD and define the boundary for the domain. MEPs are responsible for initiating, processing, and terminating CFM messages. Each MEP with the same MD and MA represent endpoints for a single service.