IPv4 OSI Model - Internet Protocol version 4 (IPv4)

What is IPv4 OSI Model?

The International Standard Organization holds a precise model for Communication Systems which is called as Open System Interconnection or the OSI Model. This layered model is a conceptualized view of how one system communicates with the other by using various protocols defined in each layer. Additionally, each layer will be designated to a well-defined part of communication system. For example, the Physical layer will define all the components of physical nature, i.e. wires, frequencies, pulse codes, voltage transmission etc. of a communication system.

The OSI Model has seven layers as shown below:

• Application Layer (Layer-7): in this layer, user application sits which should transfer data between or among hosts. For example: HTTP, file transfer application (FTP) and electronic mail etc.
• Presentation Layer (Layer-6): This layer will help you in understanding data representation in one form on a host to other host in their native representation. Data from the sender will be converted to on-the-wire data (general standard format) and at the receiver’s end; it will be converted to the native representation of the receiver.
• Session Layer (Layer-5): This layer offers session management capabilities between hosts. For example, if some host requires password verification to access and if credentials are provided, then for that session, password verification will not occur again. This layer helps in synchronization, dialog control and critical operation management (e.g., an online bank transaction).
• Transport Layer (Layer-4): This layer offers end to end data delivery between hosts. It takes data from the above layer, breaks it into minor units known as Segments and then gives it to the Network layer for transmission.
• Network Layer (Layer-3): This layer will help in uniquely identifying hosts beyond the subnets and defines the path which the packets will follow or be routed to reach the destination.
• Data Link Layer (Layer-2): This layer will take the raw transmission data (signal, pulses etc.) from the Physical Layer, make Data Frames and send it to the upper layer and vice versa. This layer also checks for transmission errors and sorts it out accordingly.
• Physical Layer (Layer-1): This layer will be dealing with hardware technology and actual communication mechanism like signaling, voltage, cable type and length, etc.

Network Layer

Network layer will be responsible to carry data from one host to another. It offers a way to allocate logical addresses to hosts and identifies them uniquely using the same. Network layer will take data units from Transport Layer and cuts them in to smaller unit called Data Packet.

Network layer will define the data path which the packets should follow for reaching the destination. Routers will work on this layer and provide mechanism for routing data to its destination.