Study Unit 4 computer systems and data communication



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Switches


Switches are the more recent technology and the accepted way of building today's networks. They are essentially high-speed multi-port bridges which are more efficient than with any other type of hub.

With switching, each connection gets "dedicated bandwidth" and can operate at full speed. As a result, a switch is often termed a 'smart hub'. In contrast, a hub shares bandwidth across multiple connections such that activity from one PC or server can slow down the effective speed of other connections on the hub.


Now more affordable than ever, Dual-speed 10/100 autosensing switches are recommended for all school networks. Schools may want to consider upgrading any hub based networks with switches to improve network performance, that is, the speed of data on the network.



Repeaters


A repeater is a device that regenerates and amplifies signals to create long-distance networks. They simply receive, amplify and rebroadcast the signals although some repeaters can provide basic error-checking. They are used to overcome distance limitations. Repeaters can be separate devices or they can be incorporated into a concentrator.

Bridges


A bridge is a device that links two homogenous packet-broadcast local networks. A bridge is used to connect two or more networks using the same address method or protocol. It is often used when LANs reach their capacity of nodes. It accepts all packets from each network addressed to devices on the other, buffers them, and retransmits them to the other network. It also monitors and manages the traffic to maintain optimum performance on both sides of the network.

Routers


Like a hub, a router is another type of device that acts as the central point among computers and other devices that are part of a network. Here is an example of a wired router.

Routers are similar to bridges in that they link two or more physically separate network segments. The network segments linked by a router, however, remain logically separate and can function as independent networks.


A router functions a little differently than a hub. In fact, a router can be considered a little "intelligent" than the hub.
Like a hub, the computers and other devices are connected to a router using network cables. To make this possible, a router is equipped with holes, called ports, in the back. Here is an example.



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