The OAM, therefore,
provides the ability to monitor the performance of a service continually, independent
of the underlying network infrastructure. In addition, it also provides the capability
to provision customer devices for services with specific performance and operational
profiles. Both the IEEE 802.1ag and Y.1731 focus on service layer fault management,
while Y.1731 augments with performance monitoring. The MEF specification 16 standardizes
around the capability to provision the customer premise equipment by a service
provider.
Connectivity Layer An Ethernet service is usually provided by a Service Provider
over a physical network infrastructure; this infrastructure could belong to and be managed
by one or more providers (or operators), each employing different network technologies
to deliver Carrier Ethernet services (e.g., SONET, WDM, native Ethernet, MPLS,
etc.). The OAM in this layer is concerned with the connectivity between the network
elements that underpin the service delivery. In Figure 2.20, this encompasses the elements
that exist between the boundaries of the Service Provider network (which, of
course, could be comprised of networks belonging to multiple independent operators)
and typically notated as being between the Provider Edge (PE) devices.
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