Table 1.3 highlights some of the key differences.
Basically, when enterprises require any connectivity in the MAN (to connect the local
branch office to headquarters, for instance) or in the WAN (to connect another office in
another region or even country to headquarters, for instance), they employ a Service
Provider (or multiple Service Providers) to offer connectivity.
As Table 1.3 illustrates, delivering services in the MAN and WAN is substantially
different than delivering them in the LAN. Apart from the exponentially higher number
of customers and connections, there is a more attendant complexity and diversity introduced
in the MAN and WAN, making manageability of services much more challenging.
The Solutions Available for Data Networking in the MAN and WAN The natural approach
to enabling data networking in the MAN and WAN was to use the existing telecommunications
infrastructure. While the telecommunication infrastructure had evolved considerably39
since its inception over a hundred years ago, it was (and still is) primarily
38 Networks here and elsewhere in the book refer to a set of interconnected devices at physically diverse
points.
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