R3303-HP HSR6800 Routers High Availability Configuration Guide

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configured on the ports of Router A through Router F. Port 1 of Router B is configured with the following
MPs—a level 5 MIP, a level 3 inward-facing MEP, a level 2 inward-facing MEP, and a level 0
outward-facing MEP.
Figure 5 CFD grading example
MEP list
A MEP list is a collection of configurable local MEPs and the remote MEPs to be monitored in the same
MA. It lists all the MEPs configured on different devices in the same MA. The MEPs all have unique MEP
IDs. When a MEP receives from a remote device a continuity check message (CCM) with a MEP ID not
included in the MEP list of the MA, it drops the message.
CFD functions
CFD works effectively only in correctly configured networks. Its functions, which are implemented through
the MPs, include:
• Continuity check (CC)
• Loopback (LB)
• Linktrace (LT)
CC
Connectivity faults are usually caused by device faults or configuration errors. Continuity check checks
the connectivity between MEPs. This function is implemented through periodic sending of CCMs by the
MEPs. A CCM sent by one MEP is intended to be received by all the other MEPs in the same MA. If a MEP
fails to receive the CCMs within 3.5 times the sending interval, the link is considered faulty and a log is
generated. When multiple MEPs send CCMs at the same time, the multipoint-to-multipoint link check is
achieved.
Router A Router B Router C Router D Router E Router F
5 5
3
5 5
3 3
3
2 2 2 2
0 0 0 0 0 0
MD level 5
MD level 3
MD Level 2 MD Level 2
MD level 0
Port
5
Outward-facing MEP and MD level
5
MIP and MD level
Maintenance association
Logical path of CFD messages
Port 1 Port 2
MD level 0 MD level 0
3
Inward-facing MEP and MD level
2 2 2 2