SNR S2940-8G-v2 Switch Configuration Guide
EFM OAM Configuration
Chapter 10
EFM OAM Configuration
10.1 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:
OAM protocol data units (OAMPDU) use destination MAC address 01-80-c2-00-00-02 of pro-
tocol, the max transmission rate is 10Pkt/s.
EFM OAM is established on the basis of OAM connection, it provides a link operation manage-
ment mechanism such as link monitoring, remote fault detection and remote loopback testing, the
simple introduction for EFM OAM in the following:
10.1.1 Ethernet OAM connection establishment
Ethernet OAM entity discovers remote OAM entities and establishes sessions with them by ex-
changing Information OAMPDUs. EFM OAM can operate in two modes: active mode and passive
mode. One session can only be established by the OAM entity working in the active mode and
ones working in the passive mode need to wait until it receives the connection request. After
an Ethernet OAM connection is established, the Ethernet OAM entities on both sides exchange
Information OAMPDUs continuously to keep the valid Ethernet OAM connection. If an Ethernet
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