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Saturday 11 April 2015

8.HUBS/REPEATERS

HUBS/REPEATERS




1. HUB is dump device.
2. HUB and REPEATERS are similar device used on different medium.
3. HUBS are used on twisted pair and fiber medium whereas REPEATERS are used on thick wire      and    thin wire medium.
4. HUBS and REPEATERS are interchangable terms.
5. Whenever hubs receives  a signal on port,it will boost the signal and send it out of all other port.
6. HUBS only facilitates communication,they do not participate in communication.
7. HUBS will not only boost the signal but also restore the signal level.
8. Communication is never destined to the hub, It is destined for another node connected through the       hub.
9. After boosting the signal,it is sent out of all ports,except the port on which it was originally                 received.
10. Every port of a hub, shares the same bandwidth.hub is a shared bandwidth device.
11. Every port of hub is a member of the same collision domain.
12. Hub is a single collision domain device.
13. Every port of hub is a member of the same broadcast domain.
14. hub is a single broadcast domain device.

HUBS/REPEATERS
HUBS/REPEATERS

ADVANTAGES-




1. Increased coverage area.
2. Increase in number of computers that can be connected.

DISADVANTAGES-



1. With increase in number of computers,the probability of computer acquiring medium has reduced.
2. With increase in number of computers,the probability of collision has increased.

*Hub is layer 1 device.Any thing that is physical in nature and used between two communicating pairs are known as layer 1 component.

e.g.wires,cables,connectors,pins,voltages boosting and repeating devices 
    are known as layer 1 device.