Network Topology
Computer network topology is the way variouscomponents of a network
(like nodes, links, peripherals, etc) are arranged. Network topologies define the
layout, virtual shape orstructure of network, not only physically but also
logically. The way in which different systems and nodes are connected and
communicate with each other is determined by topology of the network.
Types of Network Topologies
• Bus Topology
• Star Topology
• Ring Topology
• Mesh Topology
• Hybrid Topology
Bus Topology
In the bus topology, the computers are connected through a common
communication media. A special type of central wire is used as communication
media. This central wire is called Bus. The computer are attached through the bus
the ends of the bus are closed with the terminator .The terminators are used to
absorb signals.
Advantages of Bus Topology
• Easy to install and configure
• Inexpensive
• Easily extended
Disadvantages of Bus Topology
• Performance decreases
• Weak signals
• Difficult troubleshooting
Star Topology
The star topology uses a separate cable for each work station as shown in
fig.The cable connects the work station to a central device typically a HUB. The
configuration provides a more reliable network that is easily expended. With star
there is no central point of failure in the cable .if there is a problem with the cable
only the station connected to that cable is a effected .to add more work stations
simply connect another HUB
Advantages of Star Topology
• Easily expended and modified
• Easy to troubleshoot
• Multiple cable types supported by hub
Disadvantages of Star Topology
• If hub fails then entire network will fail
• Require more cables
• May require a device to rebroadcast signals across the network
Ring Topology
Every computer is connected to the next computer in the ring and each
transmits what it receives from the previous computer. The messages flow
around the ring in one direction.
Some ring network do ring token passing. A short message called token (memory
area)is passed around a ring until a computer wishes to send information to other
computers.
Advantages
• It provides an orderly network in which every device has access to the
token and can transmit.
• It performs well under a heavy load.
Disadvantages
• Failure of one computer can effect the whole network .
• Difficult to troubleshoot.
• Change mode with adding or removing a device effect the entire network.
Mesh Topology
A mesh network or mesh topology uses separate cable to connect each
device to every other device on the network, providing a straight communication
path. For sending messages, check the cable connected into two devices. A
message is send directly from sender to receiver because each one has individual
and separate connection.
Advantages
• Enhance for error tolerance provided by redundant links.
• Easy to troubleshoot.
Disadvantages
• Difficult to install and maintain.
• Expensive.
Hybrid Topology
Hybrid networks use a combination of any two or more topologies in such a
way that the resulting network does not exhibit one of the standard topologies
(e.g., bus, star, ring, etc.).A hybrid topology is always produced when two
different basic network topologies are connected. Two common examples for
Hybrid network are: star ring network and star bus network.
