Information Technology Reference
In-Depth Information
When representing an IPv6 host address with its subnet prefix, you combine the two. For
example, the IPv6 address 2001:0000:0000:0ab0:001c:1bc0:08ba:1c9a in subnet prefix
2001:0000:0000:0ab0::/60 is represented as the following:
2001:0000:0000:0ab0:001c:1bc0:08ba:1c9a/60
This section covers the major types of IPv6 addresses. IPv4 addresses are unicast, multi-
cast, or broadcast. IPv6 maintains each of these address functions, except that the IPv6
address types are defined a little differently. A special “all-nodes” IPv6 multicast address
handles the broadcast function. IPv6 also introduces the anycast address type.
Also important to understand are the IPv6 address allocations. Sections of the IPv6 ad-
dress space are reserved for particular functions, each of which is covered in this section.
To p r o v i d e y o u w i t h a f u l l u n d e r s t a n d i n g o f a d d r e s s t y p e s , t h e fo l l o w i n g s e c t i o n s d e s c r i b e
each type.
IPv6 Address Allocations
The leading bits of an IPv6 address can define the IPv6 address type or other reservations.
These leading bits are of variable length and are called the format prefix (FP). Table 9-3
shows the allocation of address prefixes. The IPv6 address space was delegated to IANA.
You can find current IPv6 allocations at
www.iana.org/assignments/ipv6-address-space.
Many prefixes are still unassigned.
Ta b l e 9 - 3
IPv6 Prefix Allocation
Binary Prefix
Hexadecimal/Prefix
Allocation
0000 0000
0000::/8
Unspecified, loopback, IPv4-compatible
0000 0001
0100::/8
Unassigned
0000 001
0200:/7
Unassigned
0000 010
0400::/7
Reserved for Internetwork Packet Exchange
(IPX) allocation
0000 1
0800::/5
Unassigned
001
1000::/4
Unassigned
001
2000::/3
Global unicast address
010
4000::/3
Unassigned
011
6000::/3
Unassigned
100
8000::/3
Reserved for geographic-based unicast addresses
101
A000::/3
Unassigned
110
C000::/3
Unassigned
