Designers defined some address types and left a lot of scope for future definitions as currently unknown requirements arise. RFC 2373 [July 1998] / IP Version 6 Addressing Architecture defines the current addressing scheme but there is already a new draft available: draft-ietf-ipngwg-addr-arch-*.txt.
Now lets take a look at the different types of prefixes (and therefore address types):
They begin with ( where "x" is any hex character, normally "0")
fe8<emphasis>x: <- currently the only one in use.</emphasis> fe9<emphasis>x:</emphasis> fea<emphasis>x:</emphasis> feb<emphasis>x:</emphasis> |
These are addresses similar to the RFC 1918 / Address Allocation for Private Internets in IPv4 today, with the added advantage that everyone who use this address type has the capability to use the given 16 bits for a maximum number of 65536 subnets. Comparable with the 10.0.0.0/8 in IPv4 today.
Another advantage: because it's possible to assign more than one address to an interface with IPv6, you can also assign such a site local address in addition to a global one.
It begins with:
fec<emphasis>x: <- most commonly used.</emphasis> fed<emphasis>x:</emphasis> fee<emphasis>x:</emphasis> fef<emphasis>x:</emphasis> |
(where "x" is any hex character, normally "0")
Today, there is one global address type defined (the first design, called "provider based," was thrown away some years ago RFC 1884 / IP Version 6 Addressing Architecture [obsolete], you will find some remains in older Linux kernel sources).
It begins with (x are hex characters)
2<emphasis>xxx</emphasis>: 3<emphasis>xxx</emphasis>: |
There are some further subtypes defined, see below:
These were the first global addresses which were defined and in use. They all start with
3ffe:
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3ffe:ffff:100:f102::1
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A special 6bone test address which will be never be globally unique begins with
3ffe:ffff:
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and is mostly shown in examples, because if real addresses are shown, its possible for someone to do a copy & paste to their configuration files. Thus inadvertently causing duplicates on a globally unique address. This would cause serious problems for the original host (e.g. getting answer packets for request that were never sent). You can still apply for one of these prefixes, see here How to join 6bone. Also some tunnel brokers still distribute 6bone test address prefixes.
These addresses, designed for a special tunneling mechanism [RFC 3056 / Connection of IPv6 Domains via IPv4 Clouds and RFC 2893 / Transition Mechanisms for IPv6 Hosts and Routers], encode a given IPv4 address and a possible subnet and begin with
2002:
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For example, representing 192.168.1.1/5:
2002:c0a8:0101:5::1
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A small shell command line can help you generating such address out of a given IPv4 one:
ipv4="1.2.3.4"; sla="5"; printf "2002:%02x%02x:%02x%02x:%04x::1" `echo $ipv4 | tr "." " "` $sla
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See also tunneling using 6to4 and information about 6to4 relay routers.
These addresses are delegated to Internet service providers (ISP) and begin with
2001:
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Prefixes to major (backbone owning) ISPs are delegated by local registries and currently they assign to them a prefix with length 35.
Major ISPs normally delegate to minor ISPs a prefix with length 48.
Multicast addresses are used for related services.
They alway start with (xx is the scope value)
ff<emphasis>x</emphasis>y: |
They are split into scopes and types:
There are many types already defined/reserved (see RFC 2373 / IP Version 6 Addressing Architecture for details). Some examples are:
All Nodes Address: ID = 1h, addresses all hosts on the local node (ff01:0:0:0:0:0:0:1) or the connected link (ff02:0:0:0:0:0:0:1).
All Routers Address: ID = 2h, addresses all routers on the local node (ff01:0:0:0:0:0:0:2), on the connected link (ff02:0:0:0:0:0:0:2), or on the local site (ff05:0:0:0:0:0:0:2)
3ffe:ffff:100:f101:210:a4ff:fee3:9566/64 <- Node's address
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3ffe:ffff:100:f101::/64 <- subnet-router anycast address
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