Comments on: Converting IPv4 to IPv6 and back

By: Abhishek

Abhishek — Thu, 23 Apr 2009 11:14:32 +0000

i want to convert 2001:0DB8::1428:57AB into an equavalent IPv4 address..!! how should i convert this into an equavalent IPv4 address..!!

By: UC IPv6

UC IPv6 — Tue, 14 Apr 2009 12:36:28 +0000

He’s showing the format of the IPv6 as compare to IPv4. Very basic.

By: Jim

Jim — Mon, 13 Apr 2009 06:12:15 +0000

He’s showing you how to accomplish 6-to-4 tunnels basically. Those tunnels always concatenate 2002::/16 with the IPv4 address. Of course you can’t just throw the IPv4 dotted decimal notation after 2002::/16 so you have to convert it to hex and create a 48 bit prefix. So for example 192.168.1.34 becomes 2002:C0A8:122::/48.

The routers then take care of rest as far as extracting the the IPv4 address from the IPv6 address then encapsulating the IPv6 packet to to be sent over an IPv4 network. Then at the other end the IPv6 packet is decapsulated from the IPv4 packet.

Yes his wording was wrong but if you work with IPv6 it’s quite clear when this kind of conversion from IPv4 to a hex address is required.

Thanks for the great trick by the way.

By: Derek Morr

Derek Morr — Thu, 09 Apr 2009 14:13:28 +0000

I’m not sure what you’re trying to accomplish.

“So the IPv4 address of 192.168.99.1 in IPv6 address format is C0A8:6301″

That’s not correct.

If you want to represent an IPv4 address as an IPv6 address, use an IPv4-mapped address. For example, ::ffff:c0a8:6301 (alternative written as ::ffff:192.168.99.1). IPv4-mapped addresses are commonly used with IPv6 wildcard sockets on a dual-stacked machine.

If you want to convert between IPv6 and IPv4 on the wire, you’d have to use one of the proposed translators that the IETF is currently defining.