Re: Shim6, was: Re: filtering /48 is going to be necessary

[Owen DeLong <owen () delong com>]

On Mar 12, 2012, at 8:56 AM, Iljitsch van Beijnum wrote:

> On 12 Mar 2012, at 16:21 , Leigh Porter wrote:
>
> > > Grass-roots, bottom-up policy process
> > > +
> > > Need for multihoming
> > > +
> > > Got tired of waiting
> > > =
> > > IPv6 PI
>
> > A perfect summation.
>
> Except that it didn't happen in that order. When ARIN approved PI the shim6 effort was well underway, but it was too 
> early to be able to know to what degree it would solve the multihoming problem. Earlier, when multi6 was stuck or 
> later, when shim6, at least as a specification, but preferably as multiple implementations, could have been evaluated 
> would both have been reasonable times to decide to go for PI instead.
>
> Of course as has been the case over and over the argument "if you give us feature X we'll implement IPv6" has never 
> borne out.

Except it didn't happen that way.

The argument wasn't "If you give us PI, we'll implement IPv6."

The argument that carried the day and is, IMHO, quite valid was "If you don't give us PI we definitely WON'T implement 
IPv6."

The inability to obtain PI was a serious detractor from IPv6 for any organization that already had IPv4 PI. Shim6 
showed no promise whatsoever of changing this even in its most optimistic marketing predictions at the time. (As you 
point out, it was well underway at that point and it's not as if we didn't look at it prior to drafting the policy 
proposal.)

Frankly, I think the long term solution is to implement IDR based on Locators  in the native packet header and not 
using map/encap schemes that reduce MTU, but that doesn't seem to be a popular idea so far.

> > Also given that people understand what PI space is and how it works and indeed it does pretty much just work for the 
> > end users of the space.
>
> The trouble is that it doesn't scale. Which is fine right now at the current IPv6 routing table size, but who knows 
> what the next decades bring. We've been living with IPv4 for 30 years now, and IPv6 doesn't have a built-in 32-bit 
> expiry date so it's almost certainly going to be around for much longer.

If IPv6 works out in the 1.6-2:1 prefix:ASN ratio that I expect or even as much as 4:1, we'll get at least another 30 
years out of it. Since we've had IPv6 now for about 15 years, it's already half way through that original 30. :p

Owen