| Salmon
IT
>>Cabling>topologies |
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The
cable topology describes the way that PC's on the network
are connected together. Each topology has its own advantages
and disadvantages. Structured Wiring Systems use the star
topology. There are three major cable topologies:
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| Ring
Topology (daisy chain) |
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In
a Ring Topology, each station is plugged into the device upstream
and downstream from itself. Phonenet and Ethernetwave are
two cabling systems that Daisy Chain devices together.
| Very
easy to put together. They require a minimum of cable
because you only need enough cable to chain the stations
together. Its easy to add more devices anywhere in the
chain. You don't have to worry about having enough network
jacks present. |
| A
component failure or cable failure in midstream will
down the entire network. Also, if you want to add a
device in the middle of the chain, the network will
be down while you add the device. The cabling for these
networks is generally out in the open, and more vulnerable
to accidental disconnections and breaks. |
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In
a bus topology, all stations are attached to the same cable.
The most popular networks using a bus topology are 10Base-2
and 10Base-5 Ethernet.
| A
bus requires less cable because you only need enough
to chain the stations together. There is no central
point of failure on a bus because there's no hub. |
| However,
a bus can be even more vulnerable to failure than a
star because any problem impacts the entire network.
A bus can make troubleshooting difficult for this very
same reason -- how do you isolate a problem? |
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In
a star topology, each station has a cable leading back to
a central hub. The most popular networks using a star topology
are 10Base-T Ethernet and Token Ring.
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star can simplify troubleshooting because stations can
be disconnected from the hub one at a time until the
problem is isolated. (Actually, you can do this with
a bus, but you'd be running all over the building.)
The hub may have extra features like LEDs that indicate
activity and errors on each port, making it even easier
to isolate problems. With the introduction of switches,
you can dramatically increase network performance by
replacing the hub with a switch. |
| It
requires more cable to wire a star. A hub failure can
knock out the entire network. Stars can be more expensive
because of the cost of the hub. |
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