EFM OAM Configuration
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12. EFM OAM Configuration
12.1
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:
Fig 12-1
OAM location in OSI model
OAM
protocol
data
units
(OAMPDU)
use
destination
MAC
address
OSI Model
Application
Presentation
Session
Transport
Network
Data Link
Physical
Higher layers
LLC
OAM(Optional)
MAC
Physical Layer
LAN
CSMA/CD
Layers