TCP/IP model

Packet

A small block of data which is transported from one computer to another.

Header

The part of the packet which contains the sender and destination addresses, the protocol being used and a packet number.

Payload

The part of the packet which contains the actual data which is being sent.

Source Address

The address of the device where the initial message has been sent from.

Destination Address

The address of the device where the message is going to.

Handshake

An agreement which must be made between two devices, before communicating over the internet.

Application

The protocols in this layer determine how the data will be transferred in applications. Web browsers, email clients and file transfer protocols operate here.

Data Link

The layer where the network hardware is located such as the network interface card and cabling. Ethernet and Wi

Internet

This layer routes the packets across the network using the IP protocol

Transport

Sets up the communication between the two devices communicating data and breaks the data in to the agreed packet size. TCP and UDP run here.

IP Address

A numerical address assigned to a device communicating data across the internet. This address changes.

Error Detection

When the receiving device detects that an error has occurred during the transmission of data. The data is then requested again.

Packet Switching

A data network technology. A message is broken in to packets and then sent across a network using the most suitable routes between the source and destination