When a node needs to resolve an IPv6 address to a MAC address, it sends an NS packet in which the destination IP address is the solicited-node multicast address corresponding to the IPv6 address. In IPv6, Neighbor Solicitation (NS) packets are used to resolve IP addresses to MAC addresses. IPv6 does not support broadcast addresses or Address Resolution Protocol (ARP). Each unicast or anycast address corresponds to a single solicited-node multicast address, which is often used in neighbor discovery and duplicate address detection. When a node has an IPv6 unicast or anycast address, a solicited-node multicast address is generated for the node, and the node joins the multicast group that corresponds to its IPv6 unicast or anycast address. Figure 6-3 shows the link-local address format.Ī solicited-node multicast address is generated using an IPv6 unicast or anycast address of a node. This mechanism enables two IPv6 nodes on the same link to communicate without any configuration, making link-local addresses widely used in neighbor discovery and stateless address configuration.ĭevices do not forward IPv6 packets with the link-local address as a source or destination address to devices on different links. When IPv6 runs on a node, a link-local address that consists of a fixed prefix and an interface ID in EUI-64 format is automatically assigned to each interface of the node.
A link-local address uses a link-local prefix of FE80::/10 as the first 10 bits (1111111010 in binary) and an interface ID as the last 64 bits. Link-local addresses are used only in communication between nodes on the same local link. Interface ID: identifies a device (host).
#Convert mac address to ipv6 64 bits#
Similar to an IPv4 subnet number, there are a maximum of 64 bits for both the global routing prefix and subnet ID. Subnet ID: is used by organizations to construct a local network (site). Currently, the first 3 bits of every assigned global routing prefix is 001. A global routing prefix is comprised of at least 48 bits. Global routing prefix: is assigned by a service provider to an organization. These components are described as follows: IPv6 global unicast addresses support route prefix summarization, helping limit the number of global routing entries.įigure 6-2 shows a global unicast address consisting of a global routing prefix, subnet ID, and interface ID. The loopback address cannot be used as the source or destination IP address of packets needing to be forwarded.Īn IPv6 global unicast address is an IPv6 address with a global unicast prefix, which is similar to an IPv4 public address. This IPv6 loopback address is usually used as the IP address of a virtual interface, such as a loopback interface.
Similar to the IPv4 loopback address 127.0.0.1, the IPv6 loopback address is used when a node needs to send IPv6 packets to itself. Devices do not forward packets with an unspecified address as the source IP address. It can be used as the source IP address of some packets, such as Neighbor Solicitation (NS) messages, in duplicate address detection. The IPv6 unspecified address is 0:0:0:0:0:0:0:0/128 or ::/128, indicating that an interface or a node does not have an IP address. IPv6 defines multiple types of unicast addresses, including the unspecified address, loopback address, global unicast address, link-local address, and unique local address. Packets sent to an IPv6 unicast address are delivered to the interface identified by that address.
Since each interface belongs to a node, the IPv6 unicast address of any interface can identify the relevant node. Instead, a multicast address can be used as a broadcast address.Īn IPv6 unicast address identifies an interface. Unlike IPv4, there is no broadcast IPv6 address. IPv6 addresses can be classified as unicast, multicast, or a new class called anycast.
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