PRELIMINARY
Technical Description
4.7.2.1 Ethernet Service OAM for Fault Management
The four main Ethernet Service OAM for FM functions are as follows:
• Continuity Check Monitoring — Continuity Check Monitoring detects
service interruption between MEPs. Continuity Check Messages (CCMs)
are sent from one MEP to another, enabling MEPs to locate other MEPs.
CCM confirmation can also be requested by an MEP from a linked MEP,
to ensure that the CCMs are sent and received without fault. The CCM
intervals can be set at 3.3 ms, 10 ms, 100 ms, 1 s, 10 s, 1 min, or 10 min.
• Remote Defect Indication
— An MEP uses Remote Defect Indication
(RDI) to communicate with linked MEPs that a fault has occurred, usually
that CCM confirmation were not received. The RDI is an indication that a
fault has occurred either at the far-end MEP or between the two MEPs.
• Loopback
— Loopback is a troubleshooting tool that verifies the
connectivity of a MEP with linked MEPs and linked Maintenance
Intermediate Points (MIPs).
• Linktrace
— Linktrace is a bidirectional continuity check used for fault
localization. When a Linktrace Message (LTM) is sent to a destination
MEP or MIP, a Linktrace Reply (LTR) is expected from all the intermediate
MIPs along the path to the destination and from the destination MEP or
MIP itself. Missing or misordered LTRs point out the location of a fault in
an efficient way.
4.7.2.2 Ethernet Service OAM for Performance Management
Performance management as defined by ITU Y.1731 is supported.
The ITU Y.1731 standard specifies the following features:
• Throughput is a measurement on the basis of the Loop Back Message
(LBM) and Loop Back Response (LBR) messages. The throughput is
measured by sending frames at an increasing rate (up to the theoretical
maximum), graphing the percentage of received frames, and reporting the
rate at which frames start being dropped. In general, this rate is dependent
on the frame size.
Up to 90 Mbps of throughput testing traffic can be generated.
• Delay Measurement (DM) can be used for on-demand OAM to measure
frame delay and frame delay variation. Frame delay and frame delay
variation measurements are performed by sending periodic frames with
DM information to the peer Maintenance End Point (MEP), and receiving
frames with DM information from the peer MEP during the diagnostic
interval. Each MEP can perform frame delay and frame delay variation
measurement. When a MEP is enabled to generate frames with DM
information, it periodically sends frames with DM information to its peer
MEP in the same ME. When a MEP is enabled to generate frames with DM
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1/22102-HRA 901 17/9 Uen PU1 | 2016-07-04
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