With increasing competition, and
increasing customer sophistication, many providers now offer a much wider range of services
and QoS options. VPLS provides a means for providers to offer multipoint services,
whereas the use of PE devices that offer per-flow queuing and traffic engineering enable
them to offer enhanced SLAs (for example, services with the sort of bounded latency and
jitter previously considered to be the domain of ATM rather than of Ethernet).
Ongoing Developments
In this section we will address some of the ongoing work addressing limitations in the
Ethernet over MPLS architecture. Necessarily this is a snapshot in time, and hopefully
the technologies presented here will find their way into network deployments over the
next several months from the time of writing.
Dynamic Multi-Segment Pseudowires
As discussed, there are various applications for MS-PWs. However, the MS-PW architecture
presents new challenges when compared with the single-segment pseudowire
(SS-PW) architecture. In the SS-PW case, the PE devices are able to rely on the MPLS
layer to provide connectivity from one PE to the other PE, and thus the pseudowire
layer need not concern itself with topology or with service restoration.
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