Better to know some... than all
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InternetworkingIt is an inevitable aspect of communication networks that because of business, organizational, political, and historical reasons, there exist many different types of networks throughout the world. More and more, it is becoming desirable, if not necessary, to interconnect these networks. Take, for example, the LANs operated by many universities around the world. These usually differ in many respects, but there has been a strong need to interconnect them so that the international academic and research community can freely exchange information. The problem of interconnecting a set of independent networks is called internetworking. Each of the participating networks is referred to as a sub network (or subnet). The role of the Interworking Units (IWU) is to carry out protocol conversion between the subnets. IWUs are used for interconnecting networks that use the same architecture but employ different protocols. Because of this, they operate at the network layer and are commonly referred to as routers. Another type of protocol converter is a gateway. Unlike a router, it is used to interconnect networks of different architectures. Gateways operate at layers above the network layer and usually encompass all the layers.  | |||||