In IPMP terminology, an IP link is a communication facility or medium over which nodes can communicate at the data-link layer of the Internet protocol suite. Types of IP links might include simple Ethernets, bridged Ethernets, hubs, or Asynchronous Transfer Mode (ATM) networks. An IP link can have one or more IPv4 subnet numbers, and, if applicable, one or more IPv6 subnet prefixes. A subnet number or prefix cannot be assigned to more than one IP link. In ATM LANE, an IP link is a single emulated local area network (LAN). With the Address Resolution Protocol (ARP), the scope of the ARP protocol is a single IP link.
Other IP-related documents, such as RFC 2460, Internet Protocol, Version 6 (IPv6) Specification, use the term link instead of IP link. Part VI uses the term IP link to avoid confusion with IEEE 802. In IEEE 802, link refers to a single wire from an Ethernet network interface card (NIC) to an Ethernet switch.