basic purpose and name the OSI layer where the following devices will be operating:

(1) repeater

 Repeaters: repeters also called regenerator, are physical hardware device. They connet two network segments and broadcast packets between them they have the primary function to regenerate the electrical signal:

·         Reshaping the wavefrom

·         Amplifying the waveform

·         Retiming the singnal, to avoid collision on the network

As signal travels along a cable, its strength or amplitude decreases. This is called attenuation. In other words, the signal attenuates as it travels along  a cable. This limits the length of a cable used to connect the computers together. Since singnal is a factor in the maximum length of a segment, repeater can cable length. A repeater has intelligence so that it takes a weak signal from one cable segment, regenerates it and passes it on to the next segment. The repeater does not amplift the original signal, it regenrates the original bit pattern.

(2) Hub

Hubs can also be called either MUlti port Tepeaters or concentrators. They are physical hardware devices. A hub is similar to a repeater, except that it broadcasts data received by any port to all other ports on the hub. Intelligent Hubs can perform basic diagnostics, and test the nodes to see if they are operating correctly. If they are not, the samrt hubs(or Intelligents Hubs) will remove the node form the network. Hubs are used to provide a physical star Topology the logical Topology is dependent on the medium Access control Protocol.

(3) Bridge

A bridge sends the data frames only to the concerned segment, thus preventing excess traffic. A bridge can split an overloaded network into two separate network, reducing the amount to traffic on each segment and thus making each network more efficient. Bridges can also be used to connect dissimilar networks like Ethernet system to a Token Ring system. Bridges are both hardware and software devices.

(4) Router

A router can connect network that use different technologies, addressing methods, media type, frame formats and speeds. A router keeps track of the address of all the segment of a network and can even determine the best path for sending data. Routers do not pass broadcast traffic.

(5) Gateway

A gateway is the Hardware software that is used to interconnect LANs and WANs. Gateway are much more complex and powerful than a router. They are slower than a router and are expensive. A grateway incorporates the functions of routers and bridges, but it can translate instruction set on sending network into corresponding instruction set of the receiving network.