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Extended star topology (Hierarchical star topology)
- Star topology where a central hub is connected by vertical cabling to other
hubs that are dependent on it. See hierarchical star topology.
Attenuation - Loss of communication signal energy.
EIA/TIA-568B specifies the maximum length of horizontal cabling for unshielded
twisted pair cable is ninety meters. In addition, you learned that the maximum
length for patch cords at the telecommunications outlet/connector is three
meters. You also learned that the maximum length for patch cords/jumpers at the
horizontal cross connect is 6 meters. Thus, the maximum distance for a run of
horizontal cabling that extends from the hub to any work station is 100 meters.
In a star topology because each of the horizontal cabling runs can radiate out
from the hub much like the spokes of a wheel, this means a local area network
using this type of topology could cover an 200 meter by 200 meter area.
When signals first leave a transmitting station, they are clean and easily
recognizable. However, the longer the cable length, the weaker and more
deteriorated the signals become as they pass along the networking media. If a
signal travels beyond that distance, there is no guarantee that when it reaches
a NIC card, the NIC card will be able to read it.
If a simple star topology cannot provide enough coverage for the area to be
networked, the star topology can be extended by using internetworking devices
that do not result in attenuation of the signal. When this occurs, the resulting
topology is referred to as an extended star topology.
So that signals will not become unrecognizable to devices receiving them on the
network, repeaters take in weakened signals, clean them up, amplify them, and
send them on their way along the network.