The most commonly used link layer protocol for Local Area Networks (LANs) is Ethernet and this is frequently used to support a range of network layer protocols, including IP. The IP datagrams are transmitted by encapsulation in Medium Access Control (MAC) frames (or LLC frames using MAC encapsulation).
Example of an IPv4 datagram (in this carrying an ICMP message) for transmission over Ethernet
IP introduces an extra protocol, known as the address resolution protocol (arp) to map between the destination hardware address in a MAC frame and an IP network address. The protocol stack is shown in the figure below together with the position of each protocol within the Open Systems Interconnection (OSI) reference model.
Protocol stack for IP over Ethernet
(You may click on a box in the diagram to find out more about the operation of each layer)
The Ethernet link layer provides the following important services to the IP network layer:
Example Packet Decodes
Medium Access Control
C. Hornig, Standard for the transmission of IP datagrams over Ethernet networks, RFC894
List of Ethernet Frame Types