Computer Networking - The TCP/IP (Transmission Control Protocol / Internet Protocol) Model

The TCP/IP Model

- TCP/IP model is also known as “DoD” model due to the fact that the U.S. Department of Defense (DoD) funded the original project from which TCP/IP was developed.

- It is now widely used because of the growth of the Internet. Obviously, Internet won’t be possible without TCP/IP!

Remember: Internet is built on TCP/IP

4 Layers of TCP/IP

The Application or Process Layer

- Application or process layer is equivalent to Application, Presentation and Session layers of the OSI model.

- It defines protocols for node-to-node application communication and also controls user-interface specifications.

- Protocols that function on this layer are Telnet, FTP, TFTP, NFS, SMTP, LPD, X Window, SNMP, DNS, DHCP, Boot P, etc.

The Host-to-Host Layer

- Host-host layer is equivalent to Transport layer of the OSI model.

- It creates reliable end-to-end communication and ensures the error-free delivery of data.

- It handles packet sequencing and maintains data integrity.

- Protocols that function on this layer are TCP and UDP.

The Internetwork or Internet Layer

- Internetwork or simply Internet layer is equivalent to Network Layer of the OSI model.

- It designates the protocols relating to the logical transmission of packets over the entire network.

- It takes care of the addressing of hosts by giving them an IP address and handles routing of packets among networks.

- Protocols that function on this layer are IP, ICMP, ARP, RARP, etc.

Note: IP (Internet Protocol) decides where a packet is to be sent and chooses the best path for data travel. IP address is a 32-bit logical address or ID that contains valuable encoded information greatly simplifying the complex task of routing. It designates that specific location of a device on the network.

The Network Access Layer

- Network layer is equivalent to Data Link and Physical layers of the OSI model.

- It monitors the data exchange between the host on the network.

- It oversees hardware addressing and defines protocols for the physical transmission of data.