Qtech QSW-2900-24T4-AC [201/209] Chapter 18

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Chapter 18 CFM Configuration

18.1 Brief introduction of CFM

CFM (Connectivity Fault Management)is a point-to-point OAM protocol defined by IEEE 802.1ag standard

which is used to manage failure of operating network, including continuity detection, loopback, tracert, trap alarm

and remote failure alarm.

18.2 Connectivity fault management overview

Connectivity fault management (CFM) is a link layer OAM (Operations, Administration and Maintenance)

mechanism used for link connectivity detection and fault location.

18.3 Basic Concepts in Connectivity Fault Detection

18.3.1 Maintenance domain

A maintenance domain (MD) is the part of network where CFM plays its role. The MD boundary is defined by

some maintenance points configured on the ports. MD is identified by MD name and is divided into 8 levels,

represented by integer 0 to 7. The bigger the number, the higher the level. A higher level MD can contain lower level

MDs, but they cannot overlap. In other words, a higher level MD covers larger area than a lower level MD.

18.3.2 Maintenance association

Maintenance association (MA) is a set of maintenance points in a maintenance domain. It is identified in the

form “MD name + MA name”.

MA works within a VLAN. Packets sent by the maintenance points in a MA carry the corresponding VLAN

tag. A maintenance point can receive packets sent by other maintenance points in the same MA.

18.3.3 Maintenance point

A maintenance point (MP) is configured on a port and belongs to a MA. MP can be divided into two types:

maintenance association end point (MEP) and maintenance association intermediate point (MIP).

a) MEP

Each MEP is identified by an integer called MEP ID. The MEPs define the range of MD. The MA and MD

that MEPs belong to define the VLAN attribute and level of the packets sent by the MEPs. MEPs are divided into

inbound MEP and outbound MEP.

In Figure 1, outbound MEPs are configured on the ports. In Figure 2, inbound MEPs are configured on the

two ports.