H3C Technologies H3C S7500E Series Switches - Manual (Page 124)

13-5
z Loopback address: The unicast address 0:0:0:0:0:0:0:1 (represented in the shortest format as ::1)
is called the loopback address and may never be assigned to any physical interface. Like the
loopback address in IPv4, it may be used by a node to send an IPv6 packet to itself.
z Unassigned address: The unicast address "::” is called the unassigned address and may not be
assigned to any node. Before acquiring a valid IPv6 address, a node may fill this address in the
source address field of an IPv6 packet. It cannot be used as a destination IPv6 address.
Multicast address
IPv6 multicast addresses listed in Table 13-2 are reserved for special purpose.
Table 13-2 Reserved IPv6 multicast addresses
Address Application
FF01::1 Node-local scope all nodes multicast address
FF02::1 Link-local scope all nodes multicast address
FF01::2 Node-local scope all routers multicast address
FF02::2 Link-local scope all routers multicast address
FF05::2 Site-local scope all routers multicast address
Besides, there is another type of multicast address: solicited-node address. A solicited-node multicast
address is used to acquire the link-layer address of a neighbor node on the same link, and is also used
for duplicate address detection (DAD). Each IPv6 unicast or anycast address has a corresponding
solicited-node address. The format of a solicited-node multicast address is as follows:
FF02:0:0:0:0:1:FFXX:XXXX
Where, FF02:0:0:0:0:1:FF is permanent and consists of 104 bits, and XX:XXXX is the last 24 bits of an
IPv6 unicast or anycast address.
Interface identifier in IEEE EUI-64 format
An interface identifier is used to identify a unique interface on a link and is 64 bits long.
Different interfaces generate IEEE EUI-64 format interface identifiers in different ways, which are
described below:
z IEEE 802 interfaces (such Ethernet interface and VLAN interface): The interface identifier is
derived from the link-layer address (MAC) of the interface. A MAC address is 48 bits long and
therefore, to get the interface identifier, the hexadecimal number FFFE needs to be inserted in the
middle of the MAC address (behind the 24 high-order bits). To ensure the interface identifier
obtained from a MAC address is unique, it is necessary to set the universal/local (U/L) bit (the
seventh high-order bit) to “1”. Thus, an interface identifier in IEEE EUI-64 format is obtained.