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calculates and records the link transmission delay and jitter (delay variation) according to the
transmission time and reception time. 1DM frames are multicast frames.
2.
Two-way frame delay measurement
The source MEP sends a delay measurement message (DMM), which carries the transmission time, to the
target MEP. Upon receiving the DMM, the target MEP responds with a delay measurement reply (DMR),
which carries the reception time and transmission time of the DMM and the transmission time of the DMR.
Upon receiving the DMR, the source MEP records the DMR reception time, and calculates the link
transmission delay and jitter according to the DMR reception time and DMM transmission time. DMM
frames and DMR frames are multicast frames.
TST
The TST function tests the bit errors between two MEPs. The source MEP sends a TST frame, which carries
the test pattern, such as pseudo random bit sequence (PRBS) or all-zero, to the target MEP. Upon receiving
the TST frame, the target MEP determines the bit errors by calculating and comparing the content of the
TST frame. TST frames are unicast frames.
Protocols and standards
•
IEEE 802.1ag,
Virtual Bridged Local Area Networks Amendment 5: Connectivity Fault
Management
•
ITU-T Y.1731,
OAM functions and mechanisms for Ethernet based networks
CFD configuration task list
For CFD to work properly, design the network by performing the following tasks:
•
Grade the MDs in the entire network, and define the boundary of each MD
•
Assign a name for each MD. Make sure that the same MD has the same name on different devices.
•
Define the MA in each MD according to the VLAN you want to monitor
•
Assign a name for each MA. Make sure that the same MA in the same MD has the same name on
different devices.
•
Determine the MEP list of each MA in each MD. Make sue that devices in the same MA maintain
the same MEP list.
•
At the edges of MD and MA, MEPs should be designed at the device port. MIPs can be designed
on devices or ports that are not at the edges.
Complete the following tasks to configure CFD:
Tasks Remarks
Required
Configuring the CFD protocol version
Optional
Creating a service instance
with the MD name
Creating a service instance
without the MD name
Required
Perform either task
Required
Configuring MIP generation rules
Required