Differences Between Routers, Hubs & Switches
Networks require a range of hardware to function. Apart from the cable, and connectors attaching those cable to devices, a number of specialized machines help move data from one location to another. Each category of networking hardware has its own level of specialization and is governed by a specific set of protocols.
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Physical Device
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A hub is like a splitter. It is also called a repeater. Computers in a network are connected to the hub by a cable. One cable passes between each computer and a socket on the hub. The can connect as many computers and devices as it has sockets. Any data coming in on one cable is copied and sent out over all connected cables. Thus, the original message sent from one computer to the hub is duplicated into many instances of the same message. The hub does not operate with addresses, only physical cables connected to it.
Data Link Device
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The switch uses addresses. The device operates at the Data Link Layer, which means it is only concerned with moving data within networks. It deal with one specific link, or hop. The switch is very similar to the hub, in that all devices are connected to it by one cable each. The switch receives an incoming message on one of the cables connected to it and directs that message to the socket it has associated with the address given in the header of the message. Thus, the switch does not broadcast the message to all devices, but to a specific device. The addressing system used for switch is called the MAC address. This is hard coded on to the network adapter of each connected device. MAC Stands for Media Access Control.
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Routing
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Routing involves reaching across many links. A router deals with IP addresses. These addresses are defined by the Internet Protocol. The router needs to operate an algorithm to decide in which direction it should forward an incoming message. The capabilities of the router, however, are limited to sending that data only to its neighboring device. That is, it uses its knowledge of its preferred route for the data to choose which of the other routers it connects to is better placed to reach the destination in the quickest possible time. However, the router is not able to specify the route the next router in the chain should use.
Other Equipment
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Two other networking devices are often found in modern networking. A bridge is very similar to a switch only it usually just connects two segments of a network rather than many individual computers. A gateway guards the connection point between a private network and a wider network, such as the Internet. It performs security services that include firewall functions and also limits Internet access by the computers within the network. Often router and gateway functions are performed on the same machine.
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References
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