In fact,
MAN interconnection soon became a vital part of an enterprise??™s communication infrastructure
(for interconnecting LANs at different locations, for Internet access, for
Intranets and Extranets, and a host of new applications).
Networking Beyond the LAN: Metropolitan Area
Networks (MANs) and Wide Area Networks (WANs)
An enterprise needing to network beyond the LAN usually has to rely on a Service
Provider for networking capability; this provider could be a telecommunications carrier, a
cable Multi-Service Operator (MSO), or some other entity that usually owns and operates
the underlying technology infrastructure and offers services over this infrastructure.
The enterprise LAN physically connects to a Service Provider??™s network??”this physical
connection is referred to as the access, the last/first mile, or the local access loop.
Specifically, a LAN device such as a router or switch is connected to a Service Provider??™s
closest Point-Of-Presence (POP) or Central Office (CO) through some physical media
via a Service Provider??™s equipment that is usually located at the customer??™s premises.
The specific equipment depends on the solution employed by the Service Provider to
offer the connectivity and will be discussed later in this chapter.
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