IPv6 Network Addressing: Additional Information

Please make sure when purchasing future technology hardware and software for departmental use that it is IPv6 ready.

For additional information, please contact the IPv6 Product Team at [email protected].

The primary motivation for IPv6 is the need to meet the demand for globally unique IP addresses. IPv6 quadruples the number of network address bits from 32 bits (in IPv4) to 128 bits, which provides more than enough globally unique IP addresses for every networked device on the planet. By being globally unique, IPv6 addressesinherently enable global reachability and end-to-end security for networked devices, functionality that is crucial to the applications and services that are driving the demand for the addresses.

Additionally, the flexibility of the IPv6 address space reduces the need for private addresses; therefore, IPv6 enables new application protocols that do not require special processing by border devices at the edge of networks.

IPv6 addresses are represented as a series of 16-bit hexadecimal fields separated by colons (:) in the format:x:x:x:x:x:x:x:x.

Following are two examples of IPv6 addresses:
2001:DB8:7654:3210:FEDC:BA98:7654:3210
2001:DB8:0:0:8:800:200C:417A


IPv6 addresses commonly contain successive hexadecimal fields of zeros. Two colons (::) may be used to compress successive hexadecimal fields of zeros at the beginning, middle, or end of an IPv6 address (the colons represent successive hexadecimal fields of zeros). The table below lists compressed IPv6 address formats.


A double colon may be used as part of the ipv6-address argument when consecutive 16-bit values are denoted as zero. You can configure multiple IPv6 addresses per interfaces, but only one link-local address.

 IPv6 Address Type Preferred Format Compressed Format
 Unicast 2001:0:0:0:DB8:800:200C:417A 2001::DB8:800:200C:417A
 Multicast FF01:0:0:0:0:0:0:101 FF01::101
 Loopback 0:0:0:0:0:0:0:1 ::1
 Unspecified 0:0:0:0:0:0:0:0::

Note: Two colons (::) can be used only once in an IPv6 address to represent the longest successive hexadecimal fields of zeros. The hexadecimal letters in IPv6 addresses are not case-sensitive.

The loopback address listed in the table above may be used by a node to send an IPv6 packet to itself. The loopback address in IPv6 functions the same as the loopback address in IPv4 (127.0.0.1).