Re: draft-ietf-ipv6-ula-central-02.txt

Thus spake "Per Heldal" <heldal@eml.cc>
> On Mon, 2007-07-09 at 10:05 -0500, Stephen Sprunk wrote:
>> > * ULA-C/G are NOT ment to be used on internet
>>
>> OTOH, there's no way for the IETF or RIRs to stop it from happening.  I'm
>> not saying it will, but it is irresponsible to claim it won't when 
>> there's
>> no mechanism to enforce that.
>
> <sarcasm>
> What is the mechanism to force operators to carry ULA prefixes?
> </sarcasm>

Money.

Sooner or later, we're going to run out of IPv4 space.  Let's say Ebay 
hadn't been able to get their PIv6 /41.  The only other viable way they'd be 
able to reach all of the new IPv6-only eyeballs is to use ULA-C/G addresses. 
The only way ISPs would be able to give their eyeballs access to that 
content is by accepting that route.  Voila, ULA-C/G becomes the de facto PI 
space.

Note that this scenario is one of several that caused ARIN to pass its PIv6 
policy last year.

> Until such mechanisms are in place ULA-prefixes are likely to be
> rejected by the majority of transit operators. ULA-blocks split in their
> individual /48s (due to incompetence, accident or malice) won't fit in
> any current or near-future routing hardware nor is there a reliable
> mechanism to manage exceptions on a mass-scale.

Routers in the DFZ are limited by the number of slots available, not by the 
length of the prefixes.  Routers don't care whether they've got a million 
/32s or half a million /32s and half a million /48s.

PI /48s do work just fine in the DFZ.  There's no reason why ULA-C/G(/L) 
/48s wouldn't work just as well.  As Jeroen showed, some ISPs can't even be 
bothered to filter 10/8 from the DFZ and that doesn't even do anything 
useful due to collisions.  Why are we expecting they'll filter ULA space 
much better, or even at all -- just because the IETF asked nicely?

S

Stephen Sprunk      "Those people who think they know everything
CCIE #3723         are a great annoyance to those of us who do."
K5SSS                                             --Isaac Asimov 

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