SNR S2989G-48TX-DC — understanding EFM OAM for Ethernet Network Management [95/553]

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S2989G-24TX Operation Manual Chapter 2 Layer 2 services

Configuration

frames.

2.8

EFM OAM

2.8.1

Introduction to EFM OAM

Ethernet is designed for Local Area Network at the beginning, but link length and

network scope is extended rapidly while Ethernet is also applied to Metropolitan Area

Network and Wide Area Network along with development. Due to lack the effectively

management mechanism, it affects Ethernet application to Metropolitan Area Network and

Wide Area Network, implementing OAM on Ethernet becomes a necessary development

trend.

There are four protocol standards about Ethernet OAM, they are 802.3ah (EFM

OAM), 802.3ag (CFM), E-LMI and Y.1731. EFM OAM and CFM are set for IEEE

organization. EFM OAM works in data link layer to validly discover and manage the data

link status of rock-bottom. Using EFM OAM can effectively advance management and

maintenance for Ethernet to ensure the stable network operation. CFM is used for

monitoring the whole network connectivity and locating the fault in access aggregation

network layer. Compare with CFM, Y.1731 standard set by ITU (International

Telecommunications Union) is more powerful. E-LMI standard set by MEF is only applied

to UNI. So above protocols can be used to different network topology and management,

between them exist the complementary relation.

EFM OAM (Ethernet in the First Mile Operation, Administration and Maintenance)

works in data link layer of OSI model to implement the relative functions through OAM

sublayer, figure is as bleow: