Advance Hardware Concepts - Networking Concepts

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Advance Hardware

1. What is attenuation?

Attenuation refers to the weakening of the signal as it travels over cable. It is sometimes referred to as roll off.
As a signal travels across wire, its square wave becomes deformed in proportion to the distance traveled. Thus, attenuation is primarily a function of cable length. If the signal travels too far, it can degrade so much that the receiving station may not be able to interpret it and communication will fail.
A repeater is can be used to boost signal strength on a baseband network so that it can travel greater distances. An amplifier performs the same function on a broadband network.

2. What is a repeater?

A repeater is a device that regenerates the signal transmitted on a cable. Repeaters allow signals to travel beyond the normal cable length limitations. A repeater does not translate or filter packets.
Repeaters have the following characteristics:

•   Used to regenerate an existing baseband signal
•   Used primarily in a coaxial bus (linear) topology
•   Segments connected by a repeater must use the same media access control (MAC) method (e.g., a repeater does can not pass traffic between Ethernet and Token Ring)
•   A repeater can pass traffic between different types of media (i.e., coax to fiber optic) if the appropriate interfaces exist
•   Segments connected by a repeater must have the same network address
•   A repeater does not accelerate or change the signal; it simply regenerates it
•   A repeater does not filter packets or limit congestion
•   A repeater will pass a broadcast
•   A repeater operates at the physical layer of the OSI model
•   The basic functionality of a repeater (signal regeneration) can be incorporated into other connectivity devices (e.g., a hub or bridge)

Because a repeater does nothing to filter or limit traffic on the network, it should be viewed primarily as a means of connecting distant workstations, not as a means of adding additional workstations. In other words, repeaters should be used to extend the length of a network but not its density.

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