PSTN Packet- and Cell-Switched Networks

The operating concept of Packet-Switched Networks (PSNs) should be familiar to you. It is the basis for the majority of LAN networking technologies. A group of end-stations connected to the same medium share the available bandwidth to exchange information in variable-length packets (or frames). With LANs, after the hardware and cabling expense, the cost of operation is minimal. With WAN networking, however, along with the cost of hardware there is a monthly PSTN access cost. PSNs provide a usage-based data transport facility as an alternative to dedicated bandwidth transport provided with T-carrier point-to-point links.

The PSTN, however, was not originally designed for shared bandwidth operation. Its ...

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