SNR S2940-8G-v2 Switch Configuration Guide
CFM-OAM Configuration
In more easy word, MEP sending and receiving the CFM messages from the local port is the
Down MEP; in contrast, it is the Up MEP. MEP inherits the attributes of MD and MA that is located.
It means the MD level and vlan Id. Maintenance base point is the only one label in the MA, it can
be called MEPID.
15.2.4 Maintenance Mid-Point
It is belongs to certain maintenance service, the mid-point of maintenance service, and configures
on the port. MIP cannot send the CFM messages actively; it can only receive the messages from
the respond, sending Reply and transmit. It is not in charge of inspection and report failure, but it
will assist MEP to undergo the failure inspection. MIP inherits the attributes of MD and MA that is
located. It means the MD level and vlan Id.
MIP is not configured directly, it develops according to certain rules of system. In the port, each
of the maintenance can only have one MIP. The following is the MIP rules:
none: Not build up the MIP node
default: If there is not a higher level of MEP on the port, and at the same time, lower level of
MIP does not exist, then it will build up MIP on particular port at this level.
explicit: If there is not a higher level of MEP on the port, but at the same time, lower level of
MEP exists and lower level of MIP does not exist, then it will build up MIP on particular port at this
level.
defer: Whether build up the MIP node, the build rules will be determine by the configured rules
of MD in the MA.
15.3 Introduction of CFM OAM Function
802.1ag provides 5 different functions: Fault detection, Fault verification and isolation, Path dis-
covery, Fault notification and Fault recovery. Thereinto, Fault recovery need to execute with other
protocols together.
15.3.1 Inspection of Failure
Maintenance base point (MEP) will send the CCM messages to Remote MEP in the same main-
tenance collection (MA) periodically. At the same time, it also receives other outlying point CCM
message. If it cannot receive the CCM message in 3 months, then it will regards as occur failure
in the link and report. The process is shown as follow:
CCM messages can also be sent to other MEP in the same MA, it is the group messages.
The last 3 bit of the group broadcast address represent different maintenance domain level, thus
it can more easy to tackle with hardware.For the lower level of MEP, after it receive higher level of
messages, the hardware can accord to group broadcast MAC address and VLAN to undergo the
transmitting directly.
The inspection of failure of the periodically sending CCM messages as follow:
• MEP cannot receive the CCM message on time, represent there is a failure occur in the MA;
• MEP checking the received CCM messages, it can find out the disagreement failure of the
sending time interval;
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