Internet Protocol Stack

Internet Protocol Stack

Internet is governed by its protocols. To give a structured approach to the internet protocols, they are classified into five layers. This not only makes them easy to understand but also provides modularity.

The five layers of the internet protocol stack are:

1. Application
2. Transport
3. Network
4. Link
5. Physical

Five Layer Internet Protocol Stack

Application Layer:

Application layer protocols mainly run on end systems. Application layer packets are called 'messages'. HTTP(Hyper Text Transfer Protocol) is one of the famous application layer protocol designed for web documents. SMTP(Simple Mail Transfer Protocol) governs email services. FTP(File Transfer Protocol) is another application layer protocol for transferring files between two end systems. DNS(Domain Name System) translates the web addresses which humans understand to IP addresses which the internet understands.

Transport Layer:

Transport layer is responsible for transportation of application level messages between communicating end systems.Transport layer messages are called 'segments'. TCP(Transmission Control Protocol) and UDP(User Datagram Protocol) are two important protocols of the transport layer. TCP provides services like reliable data transfer,timing,security etc. UDP is somewhat opposite to TCP and doesn't provide reliable data transfer.

Network Layer:

Network Layer packets are called 'datagrams'. It is the layer which mainly establishes the internet. Network layer houses the famous IP(Internet Protocol). It contains many routing protocols also. However IP and routing protocols are collectively referred to as IP protocols. The first major version of IP is IPv4(Internet Protocol version 4) who is the predecessor of another major version IPv6.

Link Layer:

Link Layer packets are called 'frames'. Some of the famous link layer protocols are Ethernet, WiFi, DOCSIS(Data Over Cable Service Interface Specification), PPP(Point-to-Point Protocol) etc. Link is the physical connection between two nodes and link layer protocol operates only between two nodes.

Physical Layer:

Physical Layer is responsible for actual transmission of bits. Protocols in physical layer are link dependent. This layer is implemented mainly using hardware.

⧪⧪⧪