Such management will be on an end-to-end basis
across the network(s) over which the service is delivered. As such, this would require
all the underlying equipment involved (and belonging to one or more operators) to also
support the IEEE 802.1ag standard. The IEEE 802.1ag is closely aligned with the work
on fault management from the Y.1731 standard.
The IEEE 802.1ag separates the Service Provider network??”the one delivering the
end-user service??”into maintenance domains, which are each essentially managed/
administered independently. These domains are typically hierarchical and encompass
the three distinct entities that are involved in delivering a service: the customers using
the service, the Service Provider delivering the service, and the operators whose networks
may be used to deliver the service. Such a framework is useful in quickly homing
in on??”and resolving an issue.
The IEEE 802.1ag uses normal Ethernet frames to communicate between the different
devices, with the only distinction being the use of a special Ethernet MAC address
identifying it as an 802.1ag message. There are fours categories of messages that are
employed to troubleshoot and manage Ethernets:
?– Continuity check messages (CCMs) These are ???I am alive??? heartbeat messages
that are issued periodically to identify any loss of service between two
(equipment/devices) endpoints or intermediate points.
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