In light of this shift, there is a pressing need
to extend Ethernet as a service beyond the enterprise in a manner that preserves its
ubiquity and cost efficiency.
Ethernet extension has usually been done using traditional TDM-based leased line
or direct dark fiber provisioning. In particular, leased line services run at slower T1
or OC-3 speeds and require costly intermediate protocol gears such as Frame Relay
Fiber and WDM 215
or asynchronous transfer mode (ATM). It is well known that these multilayered setups
suffer from huge bandwidth inefficiency and are very costly from an operational
perspective [6]. More importantly, they have failed to keep pace with today??™s gigabitlevel
Ethernet port speeds. Alternatively, enterprise Ethernet systems simply do not
offer the high-end capabilities needed for true MAN/WAN operation, for example, high
availability, QoS, management, and so on. In fact, a recent survey of IT managers indicated
that high bandwidth, low latency, low loss, and security are some of their major
requirements [12]. Along these lines, the Metro Ethernet Forum (MEF) has defined five
attributes for a Carrier Ethernet service, namely QoS, scalability, reliability/protection,
TDM support, and services management [13].
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