Ethernet Management Enterprise Ethernet OAM has traditionally lagged far behind
SONET/SDH [11]. Therefore, carriers wanting ???carrier-grade??? OAM support for their
data services have had to choose EoS delivery??”mandating a costly TDM layer. This
deficiency has prompted much work in native Ethernet OAM and new standards are
finally maturing and offering SONET-like capabilities. Broadly speaking, Ethernet
OAM defines a multisegmented hierarchical model for end-to-end management across
multiple domains, client and carrier. Here, multiple Ethernet demarcation devices
(EDD) are defined along the end-to-end (data) connection path to assist with testing
and monitoring. Specifically, client-side EDD entities reside on carrier-owned devices
that connect to customer premise equipment (CPE) and implement the carrier-tocustomer
interface, or UNI. Meanwhile, core EDD entities reside at the carrier-to-carrier
interface, or NNI.
Using this framework, three OAM layers are defined, including service, connectivity,
and link. Service-layer OAM focuses on end-to-end Ethernet visibility (UNI-to-UNI)
and implements a host of features such as continuity checks, service loopback, fault/
defect indication (signaling), and SLA monitoring (ITU-T Y.
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