IPv6 - Special Addresses



Version 6 has slightly complex structure of IP address than that of IPv4. IPv6 has reserved a few addresses and address notations for special purposes. See the table below:

  • As shown in the table, the address 0:0:0:0:0:0:0:0/128 does not specify anything and is said to be an unspecified address. After simplifying, all the 0s are compacted to ::/128.

  • In IPv4, the address 0.0.0.0 with netmask 0.0.0.0 represents the default route. The same concept is also applied to IPv6, address 0:0:0:0:0:0:0:0 with netmask all 0s represents the default route. After applying IPv6 rule, this address is compressed to ::/0.

  • Loopback addresses in IPv4 are represented by 127.0.0.1 to 127.255.255.255 series. But in IPv6, only 0:0:0:0:0:0:0:1/128 represents the Loopback address. After loopback address, it can be represented as ::1/128.

Reserved Multicast Address for Routing Protocols

  • The above table shows the reserved multicast addresses used by interior routing protocol.

  • The addresses are reserved following the same rules of IPv4.

Reserved Multicast Address for Routers/Node

  • These addresses help routers and hosts to speak to available routers and hosts on a segment without being configured with an IPv6 address. Hosts use EUI-64 based auto-configuration to self-configure an IPv6 address and then speak to available hosts/routers on the segment by means of these addresses.

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