OSI Modal

OSI stands for open system interconnection. This layer modal tolled us how the applications communicate over the network. There are 7 layers present in this layer modal. These layers are work on the internet. When two computers are connected then these layers are work on it. Otherwise when you want to transfer the files, text, image.

If you wanted to send a file from one computer to the other, then one computer is act as a receiver and the other act as a sender. These layers are work on top to bottom in sender and act from bottom to top in receiver. Each layer in this modal has own working.

1. Application layer
2. Presentation layer
3. session layer
4. Transport layer
5. Network layer
6. Data link layer
7. Physical layer

Know we will discuss the layers of the OSI modal one by one.

Application Layer

This is the top layer of the OSI Modal. This layer in the OSI modal provides the services to the user. It enables the user, whether it is human or software, to access to the network. It provides the user interface and support for services to the server such as Email, file access and file transfer, access to the system resource, surfing the network and network management. On the behalf of this layer the client request the services of the server and the server responded on this request. SMTP (simple mail transfer protocol), FTP(file transfer protocol), TFTP(trivial file transfer protocol), DNS(domain name server), SNMP(simple network management protocol) and BOOTP etc are the application layer protocols.

Presentation Layer

This is the sixth layer of the OSI modal. It performs data reformatting, data compression and encryption. Data reformatting means:  When two computers exchange data the encoding of data in sender is different from that of receiver. Presentation layer organize the sender encoding according to the receiver layer.

Session Layer

This is the fifth layer of the OSI Modal. This layer establishes, manages and terminates the user connection. It synchronizes user tasks. Synchronization involves the use of checkpoints in the data stream. If a failure occurs, only the data from the checkpoint is retransmitted.

Transport Layer

This is the fourth layer of the OSI modal. It controls the flow of data. It ensures the message is delver error free. It cut the massages into small packets. It gives the packets the most efficient transmission. SCTP, TCP and UDP are the transport layer protocols.

Network Layer

This is the third layer of the OSI modal. It is responsible for the establishing, maintain and terminating the network connection. It manages the delivery from source to the destination. IP is the most important protocol on the network layer.

Data link layer

It is the second layer of the OSI modal. It provides the services to the physical layer. It gives the framing, flow control, error control and access control to the network.

Physical Layer

This is the bottom most layer of the OSI modal. It transmits the bit stream of the data and tells what data is transmitted over the network and what control signals are used. That’s all are decided to the physical layer.

Data link layer and physical layer

These two layers underlying the LAN or WAN technology.