Network Topologies

Subject:

Business Application of Computers (BAC) CE-305

TELECOMMUNICATION NETWORK TOPOLOGIES Prepared by: Saad Wahid Moosani (CE07-112) Ata-Ur-Rahman

(CE07-078)

NETWORK TOPOLOGY • Architecture describes how a network is arranged. • Arrangement is called topology. • Network topology is the study of the arrangement or mapping of the elements (links, nodes, etc.) of a network .

BASIC TYPES OF TOPOLOGIES There are 5 main types of network topologies: • • • • •

Tree topology Bus topology Star topology Ring topology Mesh topology

TREE TOPOLOGY • Tree topologies integrate multiple star topologies together onto a bus. • In its simplest form, only hub devices connect directly to the tree bus. • This bus/star hybrid approach supports future expandability of the network much better than a bus or a star alone.

BUS TOPOLOGY • All computers and devices connected to central cable or bus. • Consists of a main run of cable with a terminator at each end. • Popular on LANs because they are inexpensive and easy to install.

BUS TOPOLOGY Advantages:

Disadvantages:

•It is cheap as it uses the least amount of cable.

•With a lot of users, the network will be slow as data has to travel through the same central cable.

•More computers can be added without disruption.

•Failure of the central cable will stop the network from working.

STAR TOPOLOGY • This is the oldest communications method coming from telephone switching systems. • Smaller computers linked to a central unit. • Central unit is called the network hub. • All data transferred from one computer to another passes through hub.

STAR TOPOLOGY Advantages:

Disadvantages:

•If a cable fails, it will only affect one workstation.

•It is more expensive as it uses the most cabling.

•More computers can be added without disruption.

•Failure of the central computer will stop the network from working.

RING TOPOLOGY • Cable forms closed ring or loop, with all computers and devices arranged along ring. • Data travels from device to device around entire ring, in one direction. • Primarily is used for LANs, but also is used in WANs. • No central file server or computer. • Useful in a decentralized environment.

RING TOPOLOGY Advantages:

Disadvantages:

•They are cheap to expand.

•If there are a lot of users on the network, it could slow down as all the data is sent along a single line.

•The data flows around the network in one direction so it is fast. •There is no reliance on a central computer.

•If one computer in the ring stops working, the whole network stops.

MESH TOPOLOGY • It uses redundant links between devices. • A true mesh has a link between each device in the network. • Most are hybrid mesh networks which have some redundant links but not all. • Installation of a mesh is more difficult because of the quantity of links. • A mesh network is relatively easy to troubleshoot and are very fault tolerant.

MESH TOPOLOGY Advantages:

Disadvantages:

• Major advantage in fault tolerance.

• Difficulty of installation and reconfiguration

•Guaranteed communications channel capacity.

• Cost of maintaining redundant link

•Relatively easy to troubleshoot.