NETWORK, NETWORK DEVICES

REPEATERS (HUB)

Repeaters operate on the physical base of the OSI model. They are used to overcome media distance and limitations on the number of PCs and Hosts. Repeater reads the signal from a cable and sends it to other segments by reproducing the same signal. They have no decision mechanism when duplicating frames and sending them to all PCs. However, they can connect segments that use the same media access protocol (Ethernet to Ethernet).

REPEATER

Repeaters are devices operating at the physical layer of OSI. The basic task of a repeater is to receive a signal from one physical medium (cable, fiber-optic, radio wave, etc.), amplify it and transmit it to another physical medium. It is used to further extend the physical size limits of networks.

Mainly used to extend a network, repeaters are very popular devices because they are very easy to install, require very little maintenance and are inexpensive.

BRIDGE

Modern, protocol-transparent bridges operate at the data link layer of the OSI reference model. Bridge devices are used to connect two essentially independent networks (which may use different network technologies – such as Ethernet and Token-Ring). A bridge handles all traffic on top of the subnets it connects. It reads each packet and examines the MAC (Media Access Control)-layer source and destination address to see where the packet came from and where it is going. This filtering capability provides an effective service to prevent local data traffic on one repeater from being passed onto other repeaters.

ROUTER

Routers operate at the network layer of the OSI reference model. Whereas a bridge only checks the source and destination address of packets, a router keeps a complete map of the network and examines the state of all paths to determine the best path to the destination of the packet. A router is used to interconnect local or wide area networks that have different physical structures and run different protocols. A router connects local area networks to wide area networks with protocols that are generally defined at the network layer of the OSI reference model.