Local-use addresses

The link-local address is the one type of local-use unicast address defined. The link-local address is for use on a single link. Link-local addresses have the following format:

Figure 1. Link-local address format

First 10 bits are 1111111010; next 54 bits are all 0; last 64 bits are the interface ID.

Restriction: A link-local address is required on each physical interface.

Link-local addresses are designed to be used for addressing on a single link for purposes such as automatic address configuration, neighbor discovery, or in the absence of routers. It also can be used to communicate with other nodes on the same link. A link-local address is automatically assigned.

Routers do not forward any packets with link-local source or destination addresses to other links.