Transmission Control Protocol and Internet Protocol Reference Model

Transmission Control Protocol and Internet Protocol is one of the conceptual models used in networking and computing systems across the globe. It is also known as the Department of Defense (DoD) Model because it was funded by the United States Department of Defense during the cold war when USA was under the threat of a nuclear war with the fellow superpower USSR.


The war seemed inevitable and some measures had to be taken to keep the defenses strong. The motive behind models like this was to create a common network between different branches of the military in case of the war breaks out so they can coordinate and defend the country better without having to deal with an unnecessary communication gap that shouldn’t be present inside and government.


One of the main functions of this model is to Interconnect different network devices on a network so they may work together to bridge the communication gap. It is also used as the communication protocols for Intranet and Extranet. Compared to its’ alternative OSI model which consist of 7 layers, TCP/IP model has only 4:

1. Application Layer – including the protocols for routing and host configuration, application layer contains the protocols that are used by the applications. One of the most familiar and known protocols of these are Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP) and Simple Mail Transfer Protocol (SMTP). This layer alone handles the work done by three different layers in the OSI model; Session layer, presentation layer, and application layer. 


2. Transport – the establishment of data channels that allows the applications to share and receive data with each other is done by the transport layer. It is responsible for end-to-end communication. Along with TCP, User Datagram Protocol (UDP) is also used in this layer.


3. Network – using Internet Protocols (IP) and Internet Control Message Protocols (ICMP), this layer perform two basic tasks and that is of identification and addressing of the host and packet routing, which simply means making sure the packets of data is transferred forward to the receiver.


4. Physical layer – it is the layer that connects the local networking system with a host or receiver. One of the major reason for its’ success is that this model is compatible with all the operating systems. Which give it a fair advantage over OSI.


But there are some disadvantages to it:

1. It has no feature to distinguish between the physical layers and data links which according to the experts is necessary.

2. It fails to describe a Bluetooth connection which is used in many networking systems.

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