[arin-ppml] Policy Proposal: Open Access To IPv6

Kevin Loch kloch at kl.net
Mon Jun 1 19:00:08 EDT 2009

Owen DeLong wrote:
> Let's run some realistic numbers into this "unsustainable growth" we 
> keep hearing about...
> There are, currently, about 32000 actively advertised ASNs
> Source: (http://www.potaroo.net/tools/asn16 Figure 11)
> The IPv4 routing table is currently somewhere around 285,000 routes for 
> an average of
> nearly 9 routes per prefix.  The IPv6 reality is much more likely to be 
> closer to 3 routes
> per prefix (in fact, the vast majority of end-user ASNs should be very 
> close to 1 prefix
> and the vast majority of ISPs will be reasonably close to that for 
> ORIGINating routes,
> but, will advertise prefixes from other end-users, obviously).

There are several factors responsible for the prefixes per ASN being
larger than the "ideal" 1.0 in IPv4:

slow-start RIR policies
mergers and acquisitions
announcement of more specifics (for whatever reason)

The contribution of slow-start RIR policies should be effectively
eliminated by the generous initial assignment sizes in IPv6.  The other
two factors will likely exist in IPv6 in similar proportions.

I looked at the list of observed more specifics from this URL:

which contains 240,289 prefixes.  That number is much higher than I
expected but yields 7.6 prefixes per ASN.

Thus excluding slow-start and mergers and acquisitions we could
still see 7.6 IPv6 prefixes per ASN if IPv6 were deployed and used to
the extent that IPv4 is.

- Kevin

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