Dell PowerEdge M420 Dell PowerConnect M8024-k User's Configuration Guide - Page 773

Higher levels have a broader, but less detailed, view of the network. As a result, a provider could include multiple operators, provided that the domains never intersect. The operator transparently passes frames from the customer and provider, and the customer does not see the operator frames. Multiple levels within a domain (say, operator) are supported for flexibility. What Entities Make Up a Maintenance Domain? Dot1ag defines three primary entities that make up the maintenance domain: Maintenance End Points (MEPs), Maintenance Intermediate Points (MIPs), and Maintenance Associations (MAs). MEPs, and MIPs MEPs and MIPs are software or sometimes hardware per-service entities where CFM functionalities are present. • MEPs define the boundary of a maintenance domain. They initiate and respond to CFM messages. MEPs prevent the leaking of CFM messages between domains (for example, among operators or between operators and customers). Each MEP has a configurable unique identifier (MEPID) in a maintenance domain. MEPs periodically issue Continuity Check Messages (CCM) to discover each other and issue SNMP traps to report connectivity losses or malformed or incorrect CCMs. A MEP can be defined as "down MEP" or an "up MEP". A down MEPs reside in a bridge that transmits CFM PDUs towards, and receives them from, the direction of the LAN. An up MEP resides in a bridge that transmits CFM PDUs towards, and receives them from, the direction of the Bridge Relay Entity. NOTE: An entity at the boundary of maintenance domain that offers connectivity and other services to systems outside the domain is referred to as a Domain Service Access Point (DoSAP). A MEP is a type of DoSAP whose services relate to connectivity fault management. • MIPs are entities within a domain that enable the outer domain to achieve end-to-end connectivity checks. MIPs passively receive CFM messages and respond back to the originating MEP. Configuring Connectivity Fault Management 773