Shim6 vs PI addressing

Jeroen Massar jeroen at
Thu Mar 2 10:31:51 UTC 2006

On Thu, 2006-03-02 at 02:21 -0800, Owen DeLong wrote:
> >> Personally, I think a better solution is to stop overloading IDR
> >> meaning onto IP addresses and use ASNs for IDR and prefixes for
> >> intradomain routing only.
> >
> > Did you notice that 32bit ASN's are coming and that IPv4 addresses are
> > 32bits? :) Which effectively means that we are going to route IPv6 with
> > an IPv4 address space. Or when one would use the 32bit ASN for IPv4:
> > routing a 32bit address space with an 32bit routing ID. The mere
> > difference
> >
> Yes, I am well aware of 32bit ASNs.  However, some things to consider:
> 1.	Just because ASNs are 32 bits doesn't mean we'll instantly
> 	issue all 4 billion of them.  The reality is that we probably
> 	only need about 18 bits to express all the ASNs well need for
> 	the life of IPv6, but, 32 is the next convenient size and there's
> 	really no benefit to going with less than 32.

True. If we would take the 170k routes that are in BGP at the moment
then a 18bits address space is enough to give every route a dedicated
ASN. The issue is that there are way more people who might want to
multihome than that, just take the number of businesses on this planet,
add some future growth and we'll end up using the 24th bit too quite
quickly. Which is, according to some people who do routing code, no
problem at all. Like shim6, see first then believe.

> 2.	In my current thinking on how to achieve ASN based IDR, we
> 	would not need ASNs for every organization that multihomes,
> 	only for each organization that provides transit.  This
> 	would greatly reduce some of the current and future demand
> 	for ASNs.

Paper/draft/description/website? :)

> > Yep, 2005-1 fits my idea pretty well. Takes care of the folks needing
> > address space now while being able to use it differently later when it
> > is needed.
> >
> > Though as Joe Abley also mentioned (and I also quite a number of times
> > already ;) anyone with even a vague definition of a plan for 200
> > customers can get a /32 IPv6 without a problem. Just check the GRH list
> > for companies in your neighbourhood who did get it.
> >
> True, but, until recently, I was being told that ARIN insisted that the
> 200 "customers" had to be non-related third parties.  E.g. Chevron
> couldn't use all their different business units as 200 customers of
> Chevron Corporate IT.  It appears based on some recent allocations that
> they may have relaxed that stance.

It might have been that ARIN was a bit stricter, the other RIR's though
have never given any real problems as far as I know. The few ones that I
heared of that couldn't get it, either didn't try or didn't want to
"lie" about their plans.


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