Cfd Functions - HPE FlexNetwork HSR6800 series Configuration Manual

Figure 5 CFD grading example
Router A
5
0
MD level 0
3
Inward-facing MEP and MD level
Outward-facing MEP and MD level
5
MIP and MD level
5
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.
LB
Similar to ping at the IP layer, loopback verifies the connectivity between a source device and a
target device. To implement this function, the source MEP sends loopback messages (LBMs) to the
target MEP. Depending on whether the source MEP can receive a loopback reply message (LBR)
from the target MEP, the link state between the two can be verified. LBM frames and LBR frames are
unicast frames.
Router B Router C
Port 1 Port 2
5
3
MD Level 2
2
2 2
0
Router D
MD level 5
MD level 3
3 3
MD Level 2
2 2
2
0 0
MD level 0
20
Router E Router F
5
5
3
2
2
0 0
MD level 0
Port
Maintenance association
Logical path of CFD messages