Mixing Ipv4 And Ipv6 - ADDER AdderLink Digital iPEPS User Manual

Mixing IPv4 and IPv6

Although IPv6 is based upon, and shares a number of similarities with IPv4,
there are great differences in their address spaces and other key details which
mean that they are not directly compatible. This means that while computers
and their operating systems can support both types, IPv4 and IPv6 networks exist
essentially as two parallel, independent entities with numerous cross over points
(known as relay routers). For the foreseeable future, while both versions coexist,
exchanging traffic between them will require many relay routers and various
transition techniques.
One such technique involves IPv4-mapped IPv6 addresses. These are used in
operating systems and applications that transparently support both IP formats.
In such cases IPv6 will be the native format with IPv4 fully supported whenever
necessary. When an IPv4 address must be incorporated, it is placed into a special
IPv6 address that has its first 80 bits set to zero and the next 16 bits set to one.
The remaining 32 bits are where the IPv4 address is embedded. When written,
the address is an amalgam of the two network types - ::ffff:192.0.2.128
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