Reference Guide

Maintenance Domains
Connectivity fault management (CFM) divides a network into hierarchical maintenance domains, as shown in the
following illustration.
A CFM maintenance domain is a management space on a network that a single management entity owns and operates.
The network administrator assigns a unique maintenance level (from 0 to 7) to each domain to define the hierarchical
relationship between domains. Domains can touch or nest but cannot overlap or intersect as that would require
management by multiple entities.
Figure 2. Maintenance Domains
Maintenance Points
Domains are comprised of logical entities called maintenance points.
A maintenance point is an interface demarcation that confines CFM frames to a domain. There are two types of
maintenance points:
• Maintenance end points (MEPs) — a logical entity that marks the end-point of a domain.
• Maintenance intermediate points (MIPs) — a logical entity configured at a port of a switch that is an
intermediate point of a maintenance entity (ME). An ME is a point-to-point relationship between two MEPs
within a single domain. MIPs are internal to a domain, not at the boundary, and respond to CFM only when
triggered by linktrace and loopback messages. You can configure MIPs to snoop continuity check Messages
(CCMs) to build a MIP CCM database.
These roles define the relationships between all devices so that each device can monitor the layers under its
responsibility. Maintenance points drop all lower-level frames and forward all higher-level frames.
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