IPv6 uses link-local addresses as a special kind of unicast IPv6 address. These addresses are not used for normal IPv6 packet flows that contain data for applications. Instead, these addresses are used by some overhead protocols and for routing. This next topic first looks at how IPv6 uses link-local addresses and then how routers create link-local addresses.
Link-Local Address Concepts
Each IPv6 host (routers included) uses an additional unicast address called a link-local address. Packets sent to a link-local address do not leave the IPv6 subnet, because routers do not forward packets sent to a link-local address. ...