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Computer Science
Computer Catlog
Comm Network Catlog

Network Components
Network Types
The OSI Model
Protocol Notations
Physical Layer
Transmission Media
Digitization and Synchronization
Physical Layer Standards
DataLink Layer
Error Checking
Retrans - Flow Control
Sliding Window Protocol
Data Link Layer Standards
Network Layer
Switching Methods
Congestion Control
Network Sub layers
Transport Layer
Transport Protocol
Transport Layer Standards
Session Layer
Session Layer Role
Session Protocol
Presentation Layer
Abstract Syntax Notation
Application Layer
Common Application
Specific Application
Message Handling
IEEE 802 Standards
ANSI FDDI Standard
Frame Relay
Broadband ISDN & ATM


    It 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.