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NETWORKS&
TOPOLOGY
BY :PRINCE KUMAR
B. SC (IT)
GAYA COLLEGE, GAYA
INDEX
Analogue and Digital signals.
Communication medias and Protocols.
Definitions of NETWORK.
TOPOLOGY & some arrangements
ANALOGUE AND DIGITAL SIGNALS
Analogue signal: A continuous time varying signal is called Analogue signal.
Digital signals: The signals having two mode of transmission either ON (1) or OFF (0) are Digital.These are used as input and output signals
COMMUNICATION MEDIA AND PROTOCOLS The process of electronically transfer of
information between two locations is known as ‘Data Communication’.
Some basic needs of Data Communication_
Message : The information to be communicated. It may be either text, image, audio, or video
file(s). Sender : Sender creates and transmits
messages. Receiver : receives the information. Medium : The channel through which information
travel from sender to receiver. Protocol : Set of rules to control and co-ordinate
the communication.
COMMUNICATION MEDIA AND PROTOCOLS
COMMUNICATION MEDIA AND PROTOCOLS The medium or channel is used in data
communication may be_ Cables : Cables or wires are used to transmit
signals from sender to receiver via a metallic pathway. It may be of several types_ Twisted pair : Two wires are wound around each
other in a helical form.In general copper or Aluminium wire used in twisted
pair wire.They are easy to handle ,flexible ,and can run more
longer distances.Generally this is used in telephonic communications.
COMMUNICATION MEDIA AND PROTOCOLS
Co-axial cables : They consist a stiff copper wire as core surrounded by an insulating material. The insulating material is encased by a cylindrical conductor normally in the form of closely woven wire mesh. Again it is covered with a plastic cover for protection termed as jacket.The inner copper wire is used to transmit signals and the woven mesh is used for ground.They have better data transmission performance w. r .t twisted pair cables.
COMMUNICATION MEDIA AND PROTOCOLS
Optical fibres : This is based on optical technology of transmission of data as a pulse of light.
An optical fibre cable consist of a thin strand of light conducting glass or plastic fibre. This fibre is very thin and flexible solid cylinder act as transmission medium for the pulses of light.
These fibres are claded over a core and finally covered by a protecting plastic material called jacket.
Faster data communication. Expensive in comparison of twisted pair and co-
axial cables.
COMMUNICATION MEDIA AND PROTOCOLS
COMMUNICATION MEDIA AND PROTOCOLS
Microwave : Communication through microwaves can be used when the sender and receiver are large distance apart from each other.
These waves are used to transmit analogue signals.this mode of transmission is greatly affected by weather condition.
Satellite : satellites are used to sending as well as receiving information globally.We can send data from one country to another country using satellite communication.WANs having large coverage often use satellites to link with LANs.Faster + less affected by weather condition.
COMMUNICATION MEDIA AND PROTOCOLS Protocols : Protocols are set of rules to
control and co-ordinate data communication. Some of protocols are http ,smtp ,ftp ,tcp / ip
and dns etc.We can perform on following tasks using protocol_
Identification of the physical connection used. Error detection and correction of the improper
message . Initiation and Termination of the communication
session. Message formatting.
DEFINITIONS OF NETWORK A computer network is a systematic
inter connection of computers that enable them to communicate with each other and share resources, data and applications.
Generally the computer networks are classified on the basis of geographical area as follows_
Local area network (LAN) Wide area network (WAN)
Metropolitan area network (MAN) Internet
DEFINITIONS OF NETWORK LAN :
Network of a few computers in a small area such as building, homes etc.
Used for communication between two or more PCs.
Medium : twisted pair wires and co-axial wires.
Because no. of computers is limited so faster communication will happened.
DEFINITIONS OF NETWORK WAN :
Group of computers that are connected in a large area such as country, continent etc.
Generally used to connect more LANs.
Medium : telephone lines, Microwaves.
Slow rate of data transmission.
DEFINITIONS OF NETWORK MAN :
Network of computer covers a large city.
Size : lies between LAN & WAN (area of radius between 5 km to 50 km).
Optical fibres and copper wire is media and “router” used to connect LANs.
Routers is a device that direct information packets to the desired destination.
Used by private organizations.
DEFINITIONS OF NETWORK The Internet :
This is a global area network that allows computers connected over network to share resources, data and applications using different protocols.
TCP/IP is used in transferring of information. The Internet provides us following services.
E-mail, Online chat, Online shopping, UseNet and several applications.
Advantages: Easily availablity of information and resources at lower cost.
Disadvantages: so many societal impacts like VIRUS, Hacking, Malwares, and Bulk-emails.
TOPOLOGY AND SOME ARRANGEMENTS Topology means arrangements of
computers connected over a network through some physical medium cables and determines the shape of network and communication pathway between nodes.
These are some types of topology under here_
Hierarchical Topology Bus Topology Star Topology Ring Topology Hybrid Topology
TOPOLOGY AND SOME ARRANGEMENTS Hierarchical Topology :
The shape of network is as like as inverted tree.
Each of child node has only one parent node.
Medium : twisted pair wire, co axial wire and optical fibres.
Advantages: Supported by most of the
hardware and software. Shared information is received
by each node. Disadvantages:
Difficult to configure so smaller in range.
While root or parent node fails the hole network is crashed.
TOPOLOGY AND SOME ARRANGEMENTS Bus Topology :
In this type of topology nodes are connected to a common line called Bus.
If a message transmitted by any node then its arrived to each node but that is accessed only by which node that one has permission otherwise it is discarded.
Connected by twisted pair, co axial and optical fibres.
Advantages: Less cabling. Having meaningful organization. Easy to implement.
Disadvantages: If the line is crashed whole network
shall be failure. Difficult to regain ones line crashed. Degrade in speed as node increases.
TOPOLOGY AND SOME ARRANGEMENTS Star topology :
In this arrangement several nodes are connected to a HUB via cables or optical fibres. When a message is sent by a node then it first goes to the hub and from hub transmitted to the destination node.
Advantages : Easy error detection and
correction. It doesn’t matter any one of node
is crashed. Easy to install.
Disadvantages : If hub fails hole network will
crashed. Large cabling. Expensive due to cast of hub.
TOPOLOGY AND SOME ARRANGEMENTS Ring Topology :
Nodes are connected in the form of ring by twisted pair as shown in the figure.
Message sent by any node moves in clockwise node to node.
Advantage : Each node is connected to
every nodes. Addition of two node doesn’t
degrade the speed. Easy to install
Disadvantage : Expensive relatively. If any node is disturbed
network will crashed.
TOPOLOGY AND SOME ARRANGEMENTS Mesh Topology :
Each node in the network is connected to every possible node in the network.
If we have n nodes in the network there are n(n-1)/2 possible ways of connectivity.
Advantages : Message delivery is more
reliable Minimal network congestion
due to more links. Disadvantages :
Difficult to implement and install.
TOPOLOGY AND SOME ARRANGEMENTS Hybrid Topology :
Mixture of any two or more topologies according to the requirement of networking arrangement.
Generally Ring and bus topologies are arranged. More reliable.
