For
a Service Provider, choosing the appropriate Carrier Ethernet delivery platform means
improved profitability and a higher level of competitiveness, whereas for end-user enterprises,
choosing the right delivery platform can mean minimizing their communication
costs and taking advantage of the required flexibility, robustness, and scalability (the
specific benefits of Carrier Ethernet are discussed fairly extensively in Chapter 1).
It is important to note that, in most cases, these delivery platforms provide
???carrier-class??? features independent of their capability to provide Ethernet services
(e.g., SONET platforms offer resiliency to failures independent and, in fact, prior to
optimizing their capability to deliver Carrier Ethernet services).
2 i.e., its assessed value decreases (and hence, the taxes associated with it)
3 TDM services still make up a large proportion of the revenue at most typical carrier Service Providers.
The Solution Framework 125
The Reference Model
Figure 4.1 depicts a simple model that is used to contextualize the discussion in Part II of
the book. This model, based partly on the work done by the MEF [1], shows four distinct
layers: Physical layer, Transport/Network layer, Ethernet layer, and Application layer.
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