PC Help Jansant - Network Topology Guide
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Basic Network Topology
Networks are made up of 2 basic components. Computers (servers, workstations)
that want to share resources between each other, and the medium (cable
or wireless) that allows communication.
Network topology refers to the physical layout of computers, cable, wireless
cells, and other network equipment. Many networks use a combination of
different topologies.
There are 5 basic network topologies
- Bus
- Star
- Mesh
- Ring
- wireless
Bus Topology
A Bus topology uses a single linear cable to connect multiple computers.
The cable is also often called a backbone, segment, or trunk. Mostly T-connectors
are used to connect computers to the cable segment. Commonly coaxial cable
is used in a bus topology. One computer at a time can transmit but all
computers listen to all traffic on the cable, only accepting packets addressed
to them. Broadcast Packets however are accepted by all computers on the
segment. A packet sent by a computer travels in both directions on the
cable, until the destination PC accepts the packet. Until the destination
computer accepts the packet the network is occupied and no other computer
can send. A bus topology needs terminators at both ends of the cable.
Without these, signals will bounce up and down the cable and the network
will crash.
Bus Topology
A bus topology is a passive topology, computers on the network do not
resend or regenerate data. This means if one computer fails the entire
network doesn't fail. A bus topology uses less cabling than a star or
mesh topology making it cheaper. An important feature is if 1 computer
fails the network does not fail. A bus topology is difficult to troubleshoot,
normally a break in the cable, in large networks this can be difficult
to isolate. The heavier the traffic on a bus the slower the network.
A bus topology with a break in the cable.
Star Topology
In a star topology, all computers will connect through a central hub
or switch. A star topology is the most common topology and is commonly
used for ethernet networks. The centralised cabling of a star topology
makes it very easy to manage. If one link in a hub goes down its very
easy to isolate the problem. If a cable breaks only the computer connected
to that cable is affected. Of course if a hub or switch completely fails
then the whole network is affected, but again is easy to isolate the problem.
A star topology is easy to add or change configurations because all connections
are in a central location. A star topology is more expensive than a bus
because of the additional cabling to the central location. There is no
need for termination. Only one computer can communicate at a time on a
star topology.
Highly scalable small office network topography
This is the easiest solution for the home and small office network, providing
fast network speeds and easy setup. The cost of cabling has decreased
over the last few years making it an attractive option.
You will need;
See the ethernet-hardware page
also.
- A NIC with RJ-45 sockets for each computer.
- A UTP cat 5, cat5e, or cat6 cable fitted with RJ-45 connectors for each computer.
- A hub or switch with enough links for each computer.
Star Topology
Mesh Topology
A mesh topology provides a connection to every computer/device on the
network. More comonly used in something like a national telephone network.
The mesh topology is fault tolerant becuse of the multiple connections.
If there is a break in the cable the data always has another route to
take, unless of course all the cables break at once, but not very likely.
A mesh topology is very expensive because of all the cabling involved.
Mesh Topology
Ring Topology
A ring topology is exactly that, a ring. The wire loops around all computers/devices
on the network with no beginning or end. There is no need for termination.
the signal travels in 1 direction on a ring being passed from computer
to computer. Each computer checks the packet for its destination and passes
it on much like a repeater would, because of this signal degeneration
is very low. Each computer has equal communication access on a ring, providing
good performance for each computer. If one computer fails or a cable link
is broken the whole network goes down (this is not the case with some
newer technologies). Trouble shooting can be difficult as isolating a
problem is not always easy. Changing a cable will disrupt the entire network.
Ring Topology
Wireless Topology
A wireless topology uses few cable (if any) to connect systems. A wireless
network is made up of transmitters that broadcast packets using radio
frequencies. The transmitter (cell) extends the radio sphere around itself.
Network devices and computers have transmitter/receiver that recieves
broadcasts from the cell and transmits back to the cell. A cell is also
called a wireless access point (WAP). The WAP is often connected to a
wired network, which might be your ADSL connection. A antenna can also
be used on or near buildings. Bluetooth and infrared can be considered
wireless connections but are better suited to temporary connections such
as mobile phones etc. A wireless network obviously does not need much
cabling, and troubleshooting failed components is very easy. Other devices
and structures can cause interference and blockages.
Wireless Topology
You will need;
See wireless hardware page also.
- A WAP that provides adaquate coverage for your requirements.
- A wireless NIC for each computer on the newtork.
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