Network

What is Network ?

Network is a collection of computers and

devices connected together via

communication devices and

transmission media.

What is Network Topology ?

A network topology refers to the layout of

the computers and devices in a 

communications network.

It refers to both the physical and logical

layout of a network.

Physical Topology Layout

 The arrangement of a cabling is the physical

   topology.

Logical Topology Layout

 The path that data travels between computers

  on a network.

Types of network topology.

THREE commonly used network topologies are:

   Star network      ⟶      

                                 

   Bus network       ⟶              

   Ring network       ⟶       

(1) Star Network Topology

 All the computers and other 

devices on the network

 connect to a central 

device, to form a star.

Two (2) types of devices that provide a common

  central connection point to all the other devices

  on the network are a hub and a switch.

*The device that provides a common central 

connection point for other devices on a 

  network.

 *All data that transfers from one device to 

  another device passes through the hub or 

  switch.

 *The hub takes a signal that comes from 

any device and passes it along to all

  the other devices in the network

Advantages:

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

Disadvantages:

1. If the hub or switch FAILS, the entire network will

    be inoperable until the device is repaired.

(2) Bus Network Topology

   A bus network consists of a single central

    cable (backbone), 

to which all computers and

    other devices connect.

The bus is the physical cable that connects the

  computers and other devices.

 The bus in a bus network transmit data,

  instructions, and information  as a series of signal.

 Those signals are sent as electrical pulses that

  travel along the length of the cable in all directions.

Each devices is connected to the single bus

  cable through T-Connector.

 A terminator  is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable.
               

Advantages:

1. Bus networks are not expensive and easy to

    install.

Disadvantages:

1. There might be disruption when the cable (backbone)

     is break. It is because all systems on the network

     connect to a single cable or backbone.

(3) Ring Network Topology

 On a ring network, 

a cable forms 

a closed loop(ring) 

with all computers 

and devices arranged

  along the ring.

Data transmitted on a ring network travels from

  device to device around the entire ring, in one

  direction (clockwise or counterclockwise)

 Token passing is one method for sending data

   around a ring.  A token, which is a special

   bit pattern, travels around the circle.

 Each device takes a turn sending and receiving

  information through the use of a token.

Advantages:

1. The transmission of data is relatively

    simple as packets (A piece of a message

    transmitted) travel in one direction only.

Disadvantages:

1. A failure in any cable or device breaks the

    loop and can take down the entire network.