Lecture 6 Network Models

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Network Model / Protocol 

A protocol is a set of rules and regulations that looks after computers on network like access method, allows physical topology, types of cabling, and speed of data transfer.

Two well-known model that allows us to deal with various aspects of networks abstractly are OSI reference model and TCP/IP model and both are based on layering.

Layering is the division of a task into sub-tasks.

Each layer performs a specific task and provides services to its layer.

Advantages of layering are code reusing, extensibility, accelerates evolution and simplifies teaching and learning and many more.

Open System Interconnection Reference Model (OSI Reference Model/OSI Model)

It describes layered communications and computer network protocol and transmission design.




Computers transfer information across networks in the form of packet and frame.

TCP/IP Model

It forms the base of present-day internet.

The layers are similar to OSI model except it is sorted into only four steps.




Network interface is also known as host to network layer.

Network layer is also known as internet layer.

Internet Protocol (IP): It is an unreliable and connectionless protocol and transports data in packets called datagrams.

Transmission Control Protocol (TCP): It is reliable connection-oriented services. Its function are error control, flow control and sequencing

User Datagram Protocol (UPD): It is an unreliable and connectionless services. It as no assurance that the packet has reached, no sequencing and no error checking.

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