TCP/IP model

TCP/IP model

1. Application layer

   • FTP, HTTP, HTTPS, SMTP, POP, IMAP
     • Provides services to applications such as web browsers and email clients. This is where requests are made to web servers or emails are sent.

2. Transport layer

   • Transmission Control Protocol (TCP)
     • Divides data sent from the application layer into packets. Checks that data sent has been received and notifies sender that data has been received.

3. Internet layer

   • Internet Protocol (IP)
     • Adds the source and destination IP addresses to the data and routes it to the recipient.

4. Network Access layer

   • Ethernet or Wi-Fi Protocols
     • Uses network-specific protocols to ensure correct transmission of data through the local network.

5. When data is transferred between computers, it is split into packets to avoid the high bandwidth needed for large files.

   • Each packet consists of:
     • Header containing the source and destination addresses and the position of the packet in the complete message.
     • Body containing some of the data.
     • Footer to inform the receiving device that this is the end of the packet.

6. The protocols involved in the transmission of the packets make up the TCP/IP suite. It is sometimes called a 'stack' as the protocols are organised into four layers through which data must pass as they are being transmitted and received.