1. Network Protocols - abhaypsoni/Network-Protocols GitHub Wiki

Network Protocols are a set of rules governing exchange of information in an easy, reliable and secure way.

The most popular model used to establish open communication between two systems is the Open Systems Interface (OSI) model proposed by ISO.

OSI Model

OSI model is not a network architecture because it does not specify the exact services and protocols for each layer. It simply tells what each layer should do by defining its input and output data.

It is up to network architects to implement the layers according to their needs and resources available.

These are the seven layers of the OSI model −

Physical layer −It is the first layer that physically connects the two systems that need to communicate. It transmits data in bits and manages simplex or duplex transmission by modem.

Data link layer − It is the firmware layer of Network Interface Card. It assembles datagrams into frames and adds start and stop flags to each frame.

Network layer − It is concerned with routing, switching and controlling flow of information between the workstations.

Transport layer − Till the session layer, file is in its own form. Transport layer breaks it down into data frames, provides error checking at network segment level.

Session layer − This layer is responsible for establishing a session between two workstations that want to exchange data.