And Now for Something Completely Different (was Re: IPv6 news)

Sun Oct 16 08:15:28 UTC 2005

>> Shifting the NAT to end system removed the objection to NAT, tho  
>> it's not entirely clear why.  Shifting NAT to the end system also  
>> happened to simplify the entire solution as well.
>
> Except for the part about having to rewrite all existing  
> implementations to take full advantage of the technology.

That was inevitable from the start.  A real locator/identifier  
separation requires a rewrite.  Any system that provided site-wide  
source address control was going to require a rewrite.

The bigger issue is that given that rewrite was inevitable, why  
didn't we have more design freedom.  Religion *is* so much fun.

> Obviously, some of the disadvantages of such an approach would be  
> that it would require both ends to play and end users wouldn't be  
> able to traceroute.  I'm sure there are many other disadvantages as  
> well.  However, if an approach like this would be technically  
> feasible (and I'm not entirely sure it would be), I suspect it  
> would get deployed _much_ faster than an approach that requires  
> every network stack to be modified. Again.  Particularly given the  
> number of folks who care about multi-homing are so small relative  
> to the number of folks on the Internet.

David, I should point out that if only a small number of folks care  
about multihoming, then only a small number of folks need to change  
their stacks.

And even in your solution, there would need to be some changes to the  
end host if you want to support exit point selection, or carry  
alternate locators in the transport.

It's just a mess.  I think that we all can agree that a real locator/ 
identifier split is the correct architectural direction, but that's  
simply not politically tractable.  If the real message that the  
provider community is trying to send is that they want this, and not  
IPv6 as it stands today, then that's the message that should be sent,  
without reference to shim6.

Tony