-----Original Message----- From: marka@isc.org [mailto:marka@isc.org] Sent: Saturday, April 03, 2010 11:42 AM To: George Bonser Cc: Larry Sheldon; nanog@nanog.org Subject: Re: legacy /8
And we would have still had the same problem of intercommunicating. We know how to talk from IPv6 to IPv4 and get the reply traffic back. The hard part is how to initiate connection from IPv4 to IPv6. The same problem would exist in your "just expand the address bits world".
Mark
Actually, Mark, I hadn't said "just expand the address", I said to tunnel v4 in v4 which we already know how to do and most routers are already capable of doing. But yes, in the case of legacy devices that don't "speak" the new protocol, some sort of state for the flow would have to be maintained in that unit's first hop (or close to first hop) gateway. Simply increasing the address header on v4 to 128 bits would have fixed this problem years ago and got rid of such problems as NAT and we wouldn't be having this issue (and it would have been completely backwards compatible as 0s would be inserted into the new expanded address bits to put the legacy space in a special address range. I wouldn't expect to work out all the details over email on a weekend but I don't think it would take 10 years, either. The fundamental issue to me is that v6 solves a lot of problems that aren't really problems for most people and to get the fix that solves the problem you do have, you must accept a bunch of additional "fixes" for problems you don't have that makes the whole thing some big unwieldy contraption. That having been said, once the world has migrated to v6, we should have an easier go of it in the future as v6 is more easily extensible. But in the meantime, we are stuck with both protocols for probably the next 20 years or so as there are going to be places that are going to run v4 internally even if they communicate v6 externally. So ... "we are going to mandate that everyone use this new and better car but it will take different fuel, use different tires, won't fit in your garage and oh, it is incompatible with all existing roads unless you load it up on one of the old style vehicles piggy-back, but new roads are being built (here's a picture of one) and might someday be available where you live. And two years from now there will be none of the old cars left." But my daughter will need a car in three years and there are no such roads here. "Oh well! The new way is much better, it is for your own good, you will see. Trust me".