North American Network Operators Group
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Re: IPv6 Advertisements

  • From: Stephen Sprunk
  • Date: Thu May 31 13:40:28 2007

Thus spake "Donald Stahl" <[email protected]> 
Current policy allows for greater-than-/48 PI assignments if the
org can justify it.  However, since we haven't told staff (via
policy) what that justification should look like, they are currently
approving all requests and several orgs have taken advantage
of that.


I can't imagine what an end-user could come up with to justify
more than a /48 but what do I know.

First of all, there's disagreement about the definition of "site", and some folks hold the opinion that means physical location. Thus, if you have 100 sites, those folks would claim you have justified 100 /48s (or one /41). Other folks, like me, disagree with that, but there are orgs out there that have tens of thousands of locations with a need for multiple subnets per location, and that could justify more than a /48 as well via pure subnet counts.

And if ARIN's primary goal is to prevent de-aggregation then
shouldn't there be another fixed allocation size (/40) and block
to prevent this?

ARIN's goal in v6 is to try to issue blocks so that aggregation is _possible_, by reserving a larger block to allow growth, but ARIN can't prevent intentional (or accidental) deaggregation, and there's too many folks who want to deaggregate for TE purposes to pass a policy officially condemning it.

So, it's entirely possible someone could get a /40 and
deaggregate that into 256 routes if they wanted to.  Given
the entire v6 routing table is around 700 routes today, it's
obviously not a problem yet :)


Obviously that's short sighted :) As for the deaggregation-
anyone deaggregating a /40 into 256 routes should have
there AS permanently bloackholed :)

I'd agree in principle, but all it takes is a brief look at the CIDR report and you'll see that nobody does anything in response to far more flagrant examples in v4. If everyone aggregated properly, we could drop over a third of the current v4 table. This makes me extremely suspicious of ISPs that continually whine about routing table bloat whenever loosening policies for small orgs is discussed.

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