MAC addressing and operation of the Ethernet frame

We used logical addresses (IP addresses) to identify machines in the network. Routing protocols determine the path to reach the destination network, but there is important questions:

• An IP address identifies the destination logically, but what is the real hardware address of the machine?

• How does a device find the physical address of the destination?

• Where will the data be finally delivered on the local network?

• Can we track data delivery?

FondamentalEthernet protocol

Ethernet protocol defines frames for sending data over a physical medium.

Complément

Each frame contains:

  • Destination MAC[1] address[2][1]

  • Source MAC[1] address

  • Payload (data)

  • Frame FCS[3] for error detection

MAC addresses are unique 48-bit identifiers for each network interface a MAC address is assigned to a network interface card. They are usually written in hexadecimal format.

ExempleMAC address example

00:1A:2B:3C:4D:5E