Reply to post: Re: redesign

IPv6 growth is slowing and no one knows why. Let's see if El Reg can address what's going on

Anonymous Coward
Anonymous Coward

Re: redesign

As often discussed here: IPv4 has no repeat no mechanism for indicating a different address length, so switching to a new IP version number was obligatory.

That's not what was suggested.

Consider a crude 'upgrade' model to an imagined IPvX:

Keep the IPv4 header as-is.

Steal part of the data field to hold a header extension with new 64-bit addresses (and other stuff if required)

Define a "magic" IPv4 address which indicates that the "real" extended IPvX addresses are at the start (or end) of the data field.

A true dual-stack IPv4/IPvX device would read the address in the header, and either route the packet as IPv4 from an old device or understand the "magic" address and retrieve the real addresses for correct IPvX routing.

An old IPv4-only device would see the packet as an IPv4 one and dumbly route it to the "magic" destination, which would be an IPv4/IPvX gateway able to send it on it's way and process replies.

It's an ugly, crude, NAT-style hack, but could offer an upgrade path to a later IPvX+1 format once IPv4-only devices had gone away.

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