3Com 4210G Series, Configuration Manual, Page: 790 / 1133

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Connectivity Fault Detection Configuration
When configuring CFD, go to these sections for information you are interested in:
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Overview
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CFD Configuration Task List
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Basic Configuration Tasks
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Configuring CC on MEPs
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Configuring LB on MEPs
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Configuring LT on MEPs
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Displaying and Maintaining CFD
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CFD Configuration Examples
Overview
Connectivity Fault Detection (CFD) is an end-to-end per-VLAN link layer Operations, Administration
and Maintenance (OAM) mechanism used for link connectivity detection, fault verification, and fault
location.
Basic Concepts in CFD
Maintenance domain
A maintenance domain (MD) defines the network where CFD plays its role. The MD boundary is
defined by some maintenance association end points MEPs configured on the ports. A MD is identified
by an MD name.
To locate faults exactly, 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 make fault location more accurate. As shown in
Figure 6-1 , MD_A
in light 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 Device A through Device E, may fail. In this case, if a connectivity fault
is also detected at the boundary of MD_B, the failure points may be any of Device B through Device D.
If the devices in MD_B operate normally, you can be sure that at least Device C is operational.