Networking tutorial for beginer and advanced user

Previously I explained about OSI model now here is work of each layer of OSI model in short. If you want to have a brief idea than visit the link given after explanation of each layer

Application Layer

Application layer is layer 7 and it denominate as the topmost layer of the OSI model and Application layer works with the applications that we use to communicate with network. It provide network services to user applications but Application layer is different than other layers of OSI model as it do not provide services to other layer of OSI model but it provide service to application outside the OSI model.

Example of These applications is Email services, Network printing services, and Database services.

For more detail visit here

Presentation layer

Presentation layer makes the data presentable. Presentation layer make sure that whatever data is sent from one system should be readable by the application layer of another system. If there is any necessary requirement presentation layer translate the data in multiple data format using a common data format

Presentation layer also provide encryption and compression of data

The Presentation Layer is composed of two sublayers:

CASE (Common Application Service Element)

SASE (Specific Application Service Element)

http://en.wikipedia.org/wiki/Presentation_layer

Session Layer

Session layer is responsible for handling the session between devices. That is start maintain and close of connection. Session layer enforce order in the communication between devices. Session layer regulate the flow of data

For more detail visit here

Transport Layer

Transport layer ensure reliable transfer of packet form source to destination. Transport layer also manger the speed of transmission- flow control.

There are two type of transmission

Connection less transmission

Connection oriented transmission

For more detail visit here

Network Layer

Network layer is 3^rd layer of OSI model. Network layer define end to end delivery of packets. Network layer is responsible for defining logical address so that any end point can be identified easily. Network layer is also responsible for defining routes and routing work so packet can be delivered easily.

Network layer do one more important task that is fragmentation of packet in smaller packet to accommodate in different media.

For more detail visit here

Data Link Layer

Data link Layer is 2^nd layer of OSI model. Basic task of The Data Link Layer is the protocol layer which transfers data between adjacent network nodes in a wide area network or between nodes on the same local area network segment. Data link layer is made up of 2 sub layers

Logical Link Control Sublayer

LLC act between different protocols such as internet protocol and MAC method.

Media Access control Sublayer.

MAC is responsible for the connection of media.

For more you should visit here

Physical Layer

Physical layer is the layer 1 of OSI model. It is lowest bottom layer. Physical layer is responsible for connection between devices. Transmission on physical layer may be digital or analog. Physical layer is responsible for the speed and flow of transmission.

Physical layer include all the network devices include Connector weather its RJ45 or BNC type, Token Ring, Media may be cable or wireless, NIC cards, switch, hub, repeaters and may be other device that required.

For more you should visit here

What is OSI MODEL?

1. Open System Interconnection model is fundamental to all communications between network devices.
2. Developed in 1974 by ISO after the American department of defense began yusing the TCP/IP Suite of protocols
3. Finally adopted in 1977. It is not the theoretical model for how communication takes place between network devices

7 Layer model

A layer is a collection of conceptually similar functions that provide services to the layer above it and receives service from the layer below it

Application, Presentation, Session, Transport, Network, Data Link, Physical

Layers

1. Each layer is separate and independent
2. Each layer has its own function but also provides a service to those layers above and below itself
3. When communicating, each OSI layers talks with the same layer in the other device for example the application layer of device A communicates with the Application Layer of Device B, by passing the data through the other layers.
4. The Application layer of each device is not concerned with how the other layers are functioning, but it does rely on them to do their job.

Layer layer OSI model and its work

How data does flows

When data is sent from the application on the source computer it goes step by step as bellow.

1. Data in the form of packet moves down through the layers of OSI layer model starting from Application layer and end at Physical Layer.
2. When Data reach to physical layer Data is ready to send over cable or medium
3. At physical layer data bits may be analogue, digital, in the form of electrical signal or radio waves.
4. When data is transmitted to destination device it travels up through the layer from physical layer to application layer of OSI Model.
5. As data moves from one layer to another layer some additional information get added as header or trailers in data and addition of this additional information is known as encapsulation and data goes encapsulated.
6. Due to this encapsulation data does not change. here is a graphical example of data encapsulation.

In next post I will explain each layer and there job role in OSI model