Qtech QSW-2900-24T-AC [203/209] Cfm configuration

18-201
18.3.4 Basic Functions of Connectivity Fault
Management
CFM works effectively only in well-deployed and well-configured networks. Its functions, which are
implemented through the maintenance points, include:
· Continuity check (CC);
· Loopback (LB)
· Linktrace (LT)
a) Continuity check
Continuity check is responsible for checking connectivity between MEPs. Connectivity fault is usually caused
by device fault or configuration error. This function is implemented through periodic sending of continuity check
messages (CCM) by the MEPs. As a multicast message, 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 CCM within 3.5 sending periods, the link is regarded
as faulty and a corresponding log is generated. When multiple MEPs send CCMs at the same time, the
many-to-many link check is achieved.
b) Loopback
Loopback is responsible for verifying connectivity between a local device and a remote device. To implement
this function, a local MEP sends a loopback message (LBM) to the remote MEP. Depending on whether the local
MEP can receive loopback reply message (LBR) from the remote MEP, the link state between the two can be
verified. LBM and LBR are unicast messages. They are used to verify the connectivity between two points.
c) Linktrace
Linktrace is responsible for identifying the path between the source MEP and the target MEP. This function is
implemented in the following way: the source sends a linktrace message (LTM) to the target MEP. After receiving
the message, the target MEP as well as the MIPs that the LTM passes send back linktrace reply message (LTR) to the
source. Based on the replying messages, the source can identify the path to the target.
18.3.5 Protocols and Standards
The connectivity fault management function is implemented in accordance with IEEE P802.1ag.
18.4 CFM Configuration
18.4.1 CFM Configuration list
Configure domain before configuring other parameter when enabling CFM. CFM command list is as
following:
· Configure cfm domain
· Configure cfm mep level
· Configure cfm mip level
· Configure remote cfm rmep level
· Configure cfm cc interval
· Enable/disable VLAN sending cfm cc enable level

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