Network Topology
Topology is the physical layout or geometric arrangement
of the components of a network.
A network topology is also the physical layout of
computers, cables, and other components on a network. There are a number of
different network topologies, and a network may be built using multiple
topologies. The different types of network layouts are Bus topology, Star
topology, Mesh topology, Ring topology, Hybrid topology and Wireless topology.
This lesson explains what is bus topology.
There are different types of topologies:
Bus Topology
The bus topology uses a single cable in a linear fashion
to connect systems together. Both ends of the cable must be terminated using
what we call a terminator. When the cable gets faulty or un-terminated, the
network collapses.
A bus topology consists of a main run of cable with a
terminator at each end. All nodes like workstations, printers, laptops, servers
etc., are connected to the linear cable. The terminator is used to absorb the
signal when the signal reaches the end, preventing signal bounce. When using
bus topology, when a computer sends out a signal, the signal travels the cable
length in both directions from the sending computer.
When the signal reaches the end of the cable length, it
bounces back and returns in the direction it came from. This is known as signal
bounce. Signal bounce will create problem in the network, because if another
signal is sent on the cable length at the same time, the two signals will
collide.
Advantages of Bus Topology:
- Easy to connect a computer or peripheral to a linear bus.
- Requires less cable length than a star topology.
Disadvantages of Bus Topology:
- Entire network shuts down if there is a break in the main cable.
- Terminators are required at both ends of the backbone cable.
- Difficult to identify the problem if the entire network shuts down.
- Not meant to be used as a stand-alone solution.
Star Topology
In a star topology, all the systems are connected to a centralized medium i.e. a hub or a switch. If the centralized medium breaks down, the whole network breaks down too but if a system in the network breaks down, it doesn't affect the network. All the information passes through hubs and switches before it can be transferred to the destination. This arrangements reduce he risk of the entire network.
All systems are connected together whit a single cable but
in an enclosed form having a ring-like shape.
Advantages of Star topology
- Highly dependable.
- Easy diagnosis of problem.
- Expansion of the network is easy.
- Network monitoring and management is centralized
Disadvantages of Star topology
- Expensive.
- Highly dependable on hubs and switches or others.
Mesh Topology
In a mesh topology all the computers are connected
together using different cables. In Mesh topology, every network device is
connected to other network devices. Mesh topology is costly because of the
extra cables needed and it is very complex and difficult to manage.
The main advantage of mesh topology is multiple paths to
the destination computer. If one link is down, we have another path to reach
the destination.
Mesh Topology is not commonly used these days.
Ring Topology
In a ring topology, all computers are connected via a
cable that loops in a ring or circle. A ring topology is a circle that has no
start and no end and terminators are not necessary in a ring topology. Signals
travel in one direction on a ring while they pass from one computer to the
next, with each computer regenerating the signal so that it may travel the
distance required.
The main advantage of Ring topology is that the signal
degeneration is low since each workstation participating in the network is
responsible for regenerating the weak signal. The disadvantage of ring topology
is, if one workstation fails, the entire network will fail.
In this topology, all nodes are connected to one – another
in the shapes of a closed loop or ring. Each device is connected directly to
two or more devices, one on either side of it. Data travels in a one direction
only. Each system can pass data to its adjacent system.
Advantages of Ring topology
- Economical (short length cable needed o set up)
- Suitable for optical fibre cable.
- Performance of network is good during peak hours.
Disadvantages of Ring topology
- Difficult to install.
- Fault diagnosis - if one node fails entire network can fail.
- Less reliable.
Hybrid Topology
Is the combination of any of the aforementioned
topologies. Hybrid topology is a mixture of different topologies. Example is
star-bus topology.
Thanks for reading...
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