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 IP 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 Ethernet link layer provides the following important services to the IP network layer:
See also
http://www.erg.abdn.ac.uk/users/gorry Date: 10/11/1995 Revised: 7/10/2003