In IPv6, link-local addresses are always assigned, along with addresses of other scopes, and are required for the internal functioning of various protocol components. In IPv4, link-local addresses are normally only used when no external, stateful mechanism of address configuration exists, such as the Dynamic Host Configuration Protocol (DHCP), or when another primary configuration method has failed. However, in IPv6 the link-local address may be derived from the interface media access control (MAC) address in a rule-based method. In Internet Protocol (IP) networks, they are assigned most often using stateless address autoconfiguration, a process that often uses a stochastic process to select the value of link-local addresses, assigning a pseudo-random address that is different for each session. Link-local addresses may be assigned manually by an administrator or by automatic operating system procedures. In IPv6, they are assigned from the block fe80:: / 10. Therefore, routers do not forward packets with link-local source or destination addresses. Link-local addresses are not guaranteed to be unique beyond their network segment. Link-local addresses are most often assigned automatically with a process known as stateless address autoconfiguration or link-local address autoconfiguration, also known as automatic private IP addressing ( APIPA) or auto-IP. In computer networking, a link-local address is a unicast network address that is valid only for communications within the subnetwork that the host is connected to.

Network address usable for communication within a subnet

Convert mac address to ipv6 link local