Carrier Ethernet is delivered across the gamut of physical media. In the First/Lastmile
or Access portion of the network, an overwhelming majority (well over 80 percent
is estimated in the U.S. according to a 2006 report by Vertical Systems Group) of the
physical infrastructure is still based on copper; fiber makes up most of the rest and is
increasingly being used in new deployments and wireless is also becoming a very viable
option as its underpinning technologies mature. Deeper in the access networks??“in the
metro core and beyond, however, fiber begins to dominate because it is a natural fit for
transmitting huge amounts of data over large distances.
1 Metro access, metro core, regional, long, and ultra-long haul are terms often employed in the context of
Service Provider transport networks; they do not identify precise physical boundaries but rather serve
to delineate the geographic reach of a transport solution. These terms also signify different distances
depending on the context; For example, in the U.S., a regional solution is usually in the several hundred
mile range, but in Europe the range may be considerably shorter.
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