Data Communication & Networking

Data Communication

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Himanshu Kumar

Data communications are the exchange of data between two devices by using some form of transmission medium such as wire cable.

  • Effectiveness of a data communications system depends on :

  1. Delivery : system must deliver the data to the correct destination.

  2. Accuracy : data delivered should be corrected & without any alteration.

  3. Timeliness : delivered data should be timely manner.

    Timeliness means that if we are sending audio or video as a data and it does not produced as the same we send then there is no meaning to sending it.. so it is very important that data should reach with timeliness.
  4. Jitter : It refers to the variation in the packet arrival time.

Data Representation

  • Texts : It is represented as a bit pattern ( a sequence of bits 0s & 1s ).

  • Numbers : It is directly converted to binary numbers.

  • Images : It is converted to bits from pixels

  • Audio : It is converted to digital and analog signals.

  • Video : It is also converted to digital and analog signals.

    Data Flow

communication between two devices can be simplex , half-duplex and full-duplex.

Data flowCommunication typeExample
SimplexUnidirectional , means only transmit or receive.Keyboards & traditional monitors.
Half - Duplexcan do both transmit and receive but not at the same time.Walkie-talkies & citizens band radio.
Full - Duplexcan do both transmit and receive at the same time.Telephone lines & video call applications.

Network

A network is set of devices ( nodes eg. computer , printer ) connected by communication links.

  • a link is communications pathway that transfers data from one device to another.

There are two types of connections :

  1. Point-to-Point : It provides a dedicated link between two devices.

    a) uses cable to connect or microwaves and satellite links.

  2. Multi-Point : It is one in which more than two specific devices share a single links.

Topology of Network

There are mainly four categories :

  • Mesh

  • Star

  • Bus

  • Ring

TopologyDescriptionAdvantageDisadvantage
Meshevery device has a dedicated links to every other device.It is robust as one link failure does not disturb other links.amount of cables & input / output ports required to connect.
Stareach device has a dedicated point to point only to central hub.It is easy to install and configure.All links are depends on the central hub, if it fails each links will disturb.
BusAll devices are connected to a long cable through drop line & tap.ease of installation as only cable to be extends to connect new device.very difficult to reconnection and fault detection and all links depends on a single cable.
RingAll devices has dedicated point to point connections with only two devices either sides of it. where each device act as a repeater.easy to install and configure as required two cable to connect.unidirectional traffic is disadvantage as a single link can disturb the full network.
Hybridwe use multiple topologies according to us to solve the constraints or to increase the strength of network.it can be fast , secure and according to the required needs.it can be very complex to design and install.

data communicationnetworking