Mailinglist Archive: opensuse (1599 mails)

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RE: [opensuse] Practicalities of IPv6
  • From: Philip Dowie <philip.dowie@xxxxxxxxxxxxxxxxxxxxxx>
  • Date: Mon, 19 Oct 2009 09:53:28 +1300
  • Message-id: <E50D0676A6F98941BC86ED082F8F2AA4363500AD81@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
I don't recall the details and it's been quite a while since I read
about it, but there is an IPv6 address range that's reserved for
mapping directly to IPv4 addresses.

Isn't that the other way around - for mapping IPv4 (in)to IPv6 ?


In a nutshell, your IPv4 address forms part of the prefix in your IPv6
addresses.

The first group is 2002, the second and 3rd is your IPv4 address, the 4th is
totally up to you, and the rest is also totally up to you, but typically used
for autoconfiguration.

each of the dotted quad in an IPv4 address is a 8 bit quantity, which when
converted to hex is a value in the range 00-ff, so if your IP address was
192.168.23.45, then the IPv6 equivalent would be
2002:c0a8:172d:xxxx:yyyy:yyyy:yyyy:yyyy (xxxx and yyyy being up to you, etc)

This gives each IPv4 address 2^80 usable addresses, and if you use the last 64
bits for autoconfig, then you still have 2^16 (65536) subnets of 2^64 each.
You could use autoconfig on some of those, and not on others. In any case,
it's a crap load of addresses, and if you happen to need more, well, this is
just what is available to the IPv4 space!


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