In layered architecture of Network Model, one whole thing is divided into small tasks. Every layer perform its task independently and pass it other for later processing.

In layered communication system, one layer deals with the task passed by its superior or its peer. The task is either initiated by layer at the lowest level or at the top most level.

OSI Model

Open System Interconnect is the  open standard of all communication systems. OSI model is established by International Standard Organization (ISO). This model has seven layers:

• Application Layer: This layer is responsible for providing interface to the application user. This layer encompasses protocols which directly interact with the user.

• Presentation Layer: This layer defines how data in the native format of remote host should be presented in the native format of host.

• Session Layer: This layer maintains sessions between remote hosts. For example, once user/password authentication is done, the remote host maintains this session for a while and does not ask for authentication again in that time span.

• Transport Layer: This layer is responsible for end-to-end delivery between hosts.

• Network Layer: This layer is responsible for address assignment and uniquely addressing hosts in a network.

• Data Link Layer: This layer is responsible for reading and writing data from and onto the line. Link errors are detected at this layer.

• Physical Layer: This layer defines the hardware, cabling wiring, power output, pulse rate etc.

Internet Model

Internet uses TCP/IP protocol suite, also known as Internet suite. This defines Internet Model which contains four layered architecture. OSI Model is general communication model but Internet Model is what the internet uses for all its communication.The internet is independent of its underlying network architecture so is its Model.

• Application Layer: This layer defines the protocol which enables user to interact with the network.For example, FTP, HTTP etc.

• Transport Layer: This layer defines how data should flow between hosts. Major protocol at this layer is Transmission Control Protocol (TCP). This layer ensures data delivered between hosts is in-order and is responsible for end-to-end delivery.

• Internet Layer: Internet Protocol (IP) works on this layer. This layer facilitates host addressing and recognition. This layer defines routing.

• Link Layer: This layer provides mechanism of sending and receiving actual data.Unlike its OSI Model counterpart, this layer is independent of underlying network architecture and hardware.