R3303-HP HSR6800 Routers High Availability Configuration Guide

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Configuring CFD
CFD is supported only when the SAP module is operating in bridge mode.
Overview
Connectivity Fault Detection (CFD) is an end-to-end per-VLAN link layer OAM mechanism used for link
connectivity detection, fault verification, and fault location. It conforms to IEEE 802.1ag CFM.
Basic CFD concepts
Maintenance domain
A maintenance domain (MD) defines the network or part of the network where CFD plays its role. An MD
is identified by its MD name.
To accurately locate faults, CFD introduces eight levels (from 0 to 7) to MDs. The bigger the number, the
higher the level and the larger the area covered. Domains can touch or nest (if the outer domain has a
higher level than the nested one) but cannot intersect or overlap.
MD levels facilitate fault location and its accuracy. As shown in Figure 3, MD_A in li
ght blue nests MD_B
in dark blue. If a connectivity fault is detected at the boundary of MD_A, any of the devices in MD_A,
including Router A through Router E, might fail. If a connectivity fault is also detected at the boundary of
MD_B, the failure points might be any of Router B through Router D. If the devices in MD_B can operate
correctly, at least Router C is operational.
Figure 3 Two nested MDs
CFD exchanges messages and performs operations on a per-domain basis. By planning MDs correctly
in a network, you can use CFD to rapidly locate failure points.
Maintenance association
A maintenance association (MA) is a part of an MD. You can configure multiple MAs in an MD as
needed. An MA is identified by the "MD name + MA name."