Network topology

-Is the study of the  arrangement or mapping of the element link,nodes etc.

Physical topology

Any given node in the LAN will have one or more links to one or more other nodes in the network and the mapping of these link and nodes onto a graph result in a geometrical shape that determines the physical topology of the network.

Logical topology

The mapping of the flow of data

1.       Linear bus

2.       Star

3.       Star-wired ring

4.       Tree

1.Linear bus

-continuos length of cable that connects TWO or MORE device together

BUS = backbone network

-only ONE computer can transfer info at a time

-The info moves through the entire length of a cable

each END of the cable must have a

TERMINATOR.

-device that absorbs the signals transmitted on a network cable

prevents signals from being bounced back along the cable and causing interference...

advantages

~ simple

~each computer is connected to a single length of cable

~often connected to a small area (office)

disadvantages

~expansion is exisiting can be difficult ! > cable must be broken to extend the cable and attach to the additional computer

~thus, other computer cannot exchange info

~if the computer is MALFUNCTIONING and causing problem on the cable > entire network will be infected !

~expensive ! most use a single piece of copper cable to connect its computers together

2.star

-central point on the network = HUB

-currently connectd to 4, 8 or 16 computers

-length between computers cable and hub must be LESS than 100m

advantages

~easy as long as there is a FREE port on the HUB

~no need to shut down when adding another computers

~when error occured, other computers not affected !

disadvantage

~hub fails = information can no longer transfer from one computer to another

~the COST is more implement than other types of network

~LARGE amount of cable is used because computer on the network must be independently connected to the hub

3.RING

-travels in ONE direction only

-information in transfer located next to it

-if it is not adress to the computer.then info will send to the next computer and so on

there is no beginning and end

Advantages

~   This type of network topology is very organized. Each node gets to send the data when it receives an   empty token. This helps to reduces chances of collision. Also in ring topology all the traffic flows in only one  direction at very high speed.

~   Even when the load on the network increases, its performance is better than that of Bus topology.

~  There is no need for network server to control the connectivity between workstations.

~   Additional components do not affect the performance of network.

~  Each computer has equal access to resources.

Disadvantages

~  Each packet of data must pass through all the computers between source and destination. This makes it slower than Star topology.

~  If one workstation or port goes down, the entire network gets affected.

~   Network is highly dependent on the wire which connects different components.

~  MAU’s and network cards are expensive as compared to Ethernet cards and hubs.

4.TREE

-Same with star and linear bus

-One type of star topology

-Also have terminator

-Hybrid(combine of 2 topology)

Advantage

Point to point for individual segments

Disadvantages

More difficult to configure and wire

Backbone line break,the intire segment goes down