3. Ethernet - data standards

Most networks break up the data they want to exchange into separate chunks called a packet. Each type of network formats its packets differently, adding or removing certain bits of extra information. For example, packets sent over the Internet will have IP-address information.

In Ethernet networks, the format for a packet is called a 'frame'. Frames include:

• The data being sent
• The MAC address of the device sending the packet
• The MAC address of the device receiving the packet
• Error checking bits

The error checking bits are, as their name suggests, checked by the receiving computer device to ensure the packet arrived intact. If it finds an error, the device either sends back a request to re-send that packet or it discards the packet.