[arin-ppml] On the topic of longer prefixes...

Chris Grundemann cgrundemann at gmail.com
Wed Jul 29 11:02:15 EDT 2009

On Tue, Jul 28, 2009 at 23:10, John Curran<jcurran at arin.net> wrote:
>> On Jul 28, 2009, at 11:39 AM, Joel Jaeggli wrote:
>> ...It seems likely that at some point networks will likely routinely
>> accept
>> longer prefixes than /24.
> Taking the long view: once ISP's are unable to obtain any additional IPv4
> allocations from the RIRs (due to free pool depletion), there will be a
> significant focus on recovery of space from less than efficient internal
> (and possibly client) assignments.  I'd expect such space to be reassigned
> to new clients very small assignments (e.g. /30), with nominal effect on
> the routing table since the covering routes are already present.
> The real question is what happens at that point when a new customer shows
> up and says that his friend's letting him to use a piece (e.g. /30) of the
> friend's 'class C' network... i.e. if new native IPv4 service requires a
> BYOA (Bring Your Own Address) approach due to lack of available addresses,
> will ISP's turn down new business that doesn't come with own IPv4 block of
> least /24 in size?

I think that it is more likely that folks will buy access where they
can get addresses rather than crafting BYOA deals.

In your example of Customer A, ISP X and friend #1; I think the most
probable outcome is that Customer A purchases a simple transit circuit
from ISP X, connecting him to friend #1's network.  Friend #1
continues to announce the /24, buys a bit more bandwidth from his
provider and everyone is happy.

I think that *if* ISPs run out of IPv4 addresses we will see quite a
few of these "ISPs of opportunity" spring up to serve the demand (at
least in the area which that ISP serves).

Folks who want to multihome will have a bit more of a challenge but I
think there are some creative solutions that can be applied with a
couple /30s (or /31s even) from distinct providers with no need to
announce them beyond said provider.  Dynamic DNS and a couple BGP
default routes spring to mind; certainly not perfect, but probably
more workable than trying to get everyone to buy into longer prefixes
on your timetable...

How is that for skrying?


> /John
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Chris Grundemann

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