PLANET WGSW-52040 - Manual (Page 119)

Chapter 14 EFM OAM Configuration
14.1 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:
Figure 14-1: OAM location in OSI model
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