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    Networking And Internetworking Devices


    Networking And Internetworking Devices
    Two or more devices connected for the purpose of sharing data or resources are stations on a
    Network. Putting together a network is often more complicated than simply plugging cable into a hub. A local area network (LAN) may need to cover more distance than its media can handle effectively. Or the number of stations may be too great for efficient frame delivery or management of the network and the network may need to be subdivided. In the first case, a device called a repeater or regenerator is inserted into the network to increase the coverable distance. In the second, a device called a bridge is inserted for traffic management.
                    When two or more separate networks are connected for exchanging data or resources, they become an internetwork (or internet).Linking a number of LANs into an internet required additional internetworking devices called routers and gateways. These devices are designed to overcome obstacles to interconnection without disrupting the independent functioning of the networks.
    An internet is an interconnection of individual networks. To create an internet, we need internetworking devices called routers and gateways.
                    Note: Do not confuse the term internet (lowercase i) with the internet (Uppercase I).The first is a generic term used to mean an interconnection of networks. The second is the name of a specific worldwide network.
    An internet is different from the Internet.
                    As mentioned above, networking and internetworking devices are divided into four categories: repeaters, bridges, routers, and gateways.
                    Each of these four device types interacts with protocols at different layers of the OSI model. Repeaters act only upon the electrical components of a signal, and are therefore active only at the physical layer, Bridges utilize addressing protocols, and can affect the flow control of a single LAN: they are most active at the data link layer. Routers provide links between two separate but same type LANs,and are most active at the network layer.Finally,gateways provide translation services between incompatible LANs or applications, and are active in all of the layers.Each of these inter networking devices
    also operates in all of the layers below the one in which it is most active.




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