2.1 Network Topology

8/3/2019 2.1 Network Topology

1/29


2/29

Network Basics

Network Topology


3/29

A network topology refers to the layout ofthe computers and devices in a

communications network.

It refers to both the physical and logicallayout of a network.


4/29

Diagram ofdifferent network topologies.

Ring

Star

Bus


5/29

Physical Topology

The arrangement of a cabling is the physicaltopology.

Logical Topology

The path that data travels between computeron a network is the logical topology.


6/29

Types of network topology.

Three commonly usednetwork topologies are:

Bus network

Starnetwork

Ring network


7/29

BUS NETWORKTOPOLOGY


8/29

Bus Network Topology

A bus network consists of a single centralcable (backbone), to which all computers andotherdevices connect.

T-Connector

Terminator

Backbone


9/29


The bus is the physical cable that connects thecomputers and otherdevices.

The bus in a bus network transmit data,

in

struction

s, and

in

formation

as a series ofsignal.

Those signals are sent as electrical pulses thattravel along the length of the cable in all directions.


10/29


Each devices is connected to the single buscable through T-Connector.

Aterminatoris required at each end of the bus

cable to prevent the signal from bouncing backand forth on the bus cable.

T-Connector

Terminator

Backbone


11/29

When a sending device transmits data, theaddress of the receiving device is includedwith the transmission.

If the device address does not match theintended address for the data, the deviceignores the data.

If the data does match the device address,the data is accepted.

All devices receive the data but only the

receiving device accept them.



12/29


Advantages:

1. Bus networks are inexpensive and easy to install.

2. Computers and otherdevices can be attachedanddetached at any point on the bus withoutdisturbing the rest of the network.

3. Failure of one device usually does not affect therest of the bus network.


13/29


Disadvantages:

1. There might be disruption when computer orotherdevices are added or removed.

2. Because all systems on the network connect toa single cable or backbone, a break in the cablewill prevent all systems from accessing the

network.

3. It is difficult to identify the problem if the entirenetwork shut down.


14/29

STAR NETWORKTOPOLOGY


15/29

Star Network Topology

All the computers and otherdevices on thenetwork connect to a central device, thus forminga star.


16/29


Two types ofdevices that provide a commoncentral connection point to all the otherdeviceson the network are a hub and a switch.

Hub / Switch


17/29


The device that provides a common centralconnection point for otherdevices on anetwork.

All data that transfers from one device toanother passes through the hub or switch.

The hub takes a signal that comes from anydevice and passes it along to allthe otherdevices in the network.

Hub / Switch

Hub / Switch


18/29


Advantages:

1. If one device fails, only that device is affected.

2. Devices can be added to or removed fromnetwork with little orno disruption.

3. Easy to troubleshoot and isolate problem.


19/29


Disadvantages:

1. If the hub or switch fails, the entire network willbe inoperabled.

2. Requires more cable than most of the othertopologies.

3. More expensive because of the cost of thehub/switch.


20/29

RING NETWORKTOPOLOGY


21/29

Ring Network Topology

On a ring network, a cable forms a closed loop(ring) with all computers anddevices arrangedalong the ring.


22/29


Data transmitted on a ring network travels fromdevice to device around the entire ring, in onedirection (clockwise or counterclockwise)

Token passing is on

e method

for send

in

gd

ataaround a ring

Each device takes a turn sending and receiving

in

formation

through theuse of a token.


23/29


The token along with any data is sent from thefirst device to the seconddevice which extracts thedata addressed to it and adds any data it wishesto send.

Then seconddevice passes the token anddata tothe thirddevice, etc. until it comes back around tothe first device again.

Only the device with the token is allowed to senddata . All otherdevices must wait for the token tocome to them.


24/29



25/29


Advantages:

1. The transmission ofdata is relativelysimple as packets travel in one direction only.

2. Cable faults are easily located, makingtroubleshooting easier.

3. The uses of token passing enables all devices ina ring topology to share the network resourcesfairly.


26/29


Disadvantages:

1. A failure in any cable ordevice breaks theloop and can take down the entire network.

2. Data packets must pass through every computertherefore, this makes it slower.

3. A ring network can span a largerdistance than abus network, but it is more difficult to install.


27/29

DEFINITION ADVANTAGES DISADVANTAGES

A bus networkconsists of asingle central

cable (backbone),to which all

computers andother devices

connect.

Inexpensive and

easy to install.

There might bedisruption when

computer or otherdevices are added

or removed.

Other devices ca beattached or detached

without disturbing

the network.

Failure of one deviceusually does not

affect the restof the network.

The break in themain cable(backbone)

will prevent all systems

from accessing thenetwork.

It is difficult toidentify the problemif the entire network

Shut down.

SUMMARY:

BUS NETWORK TOPOLOGY


28/29


All the computersand other devices

on the networkconnect to acentral device,thus forming a

star.

If one device fails,only that device

is affected.

If the hub or switchfails, the entire

network will beinoperabled.

Devices can be addedor removed fromnetwork with no

disruption.

Easy totroubleshoot andisolate problem.

Requires more cablesthan most of the

other topologies.

More expensivebecause of the

cost of hub/switch.

SUMMARY:

STAR NETWORK TOPOLOGY


29/29

SUMMARY:


On a ring network,a cable forms a

closed loop (ring)with all computersand devices

arrangedalong the ring.

Transmission of datais simple as packets

travel in onedirection only.

A failure in any cableor device breaks the

loop and can take

down entirenetwork.

Cabel faults are easilylocated, makingtroubleshooting

easier.

All devices in ringtopolgy share thenetwork resources

fairly.

Data packets mustpass through every

computer, thus make

it slower.

More difficult toinstall than abus network.

RING NETWORK TOPOLOGY

Documents

2.1 Network Topology