A network backbone or backbone network is a part of the computer network system or infrastructure which interconnects several pieces of networks, offering a part for the exchange of data between subnetworks or LANs. The backbone network could tie together various networks in the same infrastructure or building or over wide areas or in different buildings in the campus environment. Generally, the backbone network’s capacity is better than the networks connected to it.
When several networks are interconnected, communication problems may arise among networks. Hence a broadband or fibre optic backbone is used to connect all networks on the internet work. LANs are interconnected through repeater, bridge, router or gateway. Let us discuss each of them.
A repeater is a low-level device that transmits bits of information from one network to another. It is a dumb device. It does not have its own software. It blindly copies bits of information without understanding what it is doing. It makes two physical networks into logically one network. It is similar to the physical layer of the seven-layer model.
A bridge is more powerful than a repeater. It connects two networks at the data link layer. It is useful when two networks have different data link layers but the same network layer.
A router connects LANs having same transport layer, but different network layers. Routers are more expensive than bridges. There are devices which combine the features of bridge and router. These devices are called brouters.
A Gateway connects LANs with different protocols. It operates at application layer of OSI seven-layered model. It picks the packets of data from a LAN, restructures the packets according to the protocol of receiving LAN, then transmits the packet. It can connect two LANs,
MODEM (MOdulation-DEModuIation) is a device that translates binary data into analog signals while sending the information. It translates back the analog signals into digital data at the receiving end.