1731EthOAM). In particular,
the latter collects statistics based upon carrier-settable thresholds and compares
against SLA metrics for packet delay, packet jitter, packet loss, and so on. Client service-
specific OAM is also possible here. Meanwhile, the connectivity OAM layer is somewhat
similar, but more focused on multipoint features between carrier edge devices
(IEEE 802.1ag). Finally, transport/link-layer OAM (IEEE 802.3ah) handles localized
(link-level) threshold alarms, remote failure indication, and loopback testing functions.
Overall, multilayer OAM enables rapid segment-by-segment fault localization between
the EDD elements, helping reduce management costs and minimize truck rolls.
214 Chapter 8
As of today, however, only the Ethernet services layer OAM standard has been ratified,
although the others are close to being approved. Broader vendor support and carrier
adoption will also take time.
Drivers for This Solution
In light of the technologies and standards just described, the evolution of fiber-based
Ethernet transmission is now taking shape. Today, the primary drivers for Ethernet
services over fiber/WDM are the rapid growth in corporate data-center needs and
much-improved end-user access technologies [2].
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