minimum IPv6 announcement size

bmanning at bmanning at
Fri Sep 27 04:57:18 UTC 2013

 Yup.  Seen/Heard all that.  Even tooted that horn for a while.
 /64 is an artifical boundary - many/most IANA/RIR delegations are in the top /32
 which is functionally the same as handing out traditional /16s.  Some RIR client
 are "bigger" and demand more, so they get the v6 equvalent of /14s or smaller.
 Its the _exact_ same model as v4 in the previous decade.  With the entire waste
 in the bottom /64.

 Its tilting at windmills, but most of the community has "drunk the koolaide"
 on wasteful /v6 assignment.   What a horrific legacy to hand to our children
 (and yes, it will hit that soon)


On Thu, Sep 26, 2013 at 01:18:50PM -0700, Darren Pilgrim wrote:
> On 9/26/2013 1:07 PM, joel jaeggli wrote:
> >
> >On Sep 26, 2013, at 12:29 PM, Darren Pilgrim <nanog at>
> >wrote:
> >
> >>On 9/26/2013 1:52 AM, bmanning at wrote:
> >>>sounds just like folks in 1985, talking about IPv4...
> >>
> >>The foundation of that, though, was ignorance of address space
> >>exhaustion.  IPv4's address space was too small for such large
> >>thinking.
> >
> >The first dicussion I could find about ipv4 runnout  in email
> >archives is circa 1983
> >
> >>IPv6 is far beyond enough to use such allocation policies.
> >
> >There are certain tendencies towards profligacy that might
> >prematurely influence the question of ipv6 exhaustion and we should
> >be on guard against them allocating enough /48s as part of direct
> >assignments  is probably not one of them.
> That's just it, I really don't think we actually have an exhaustion risk 
> with IPv6.  IPv6 is massive beyond massive.  Let me explain.
> We have this idea of the "/64 boundary".  All those nifty automatic 
> addressing things rely on it.  We now have two generations of hardware 
> and software that would more or less break if we did away with it.  In 
> essence, we've translated an IPv4 /32 into an IPv6 /64.  Not great, but 
> still quite large.
> Current science says Earth can support ten billion humans.  If we let 
> the humans proliferate to three times the theoretical upper limit for 
> Earth's population, a /64 for each human would be at about a /35's worth 
> of /64's.  If we're generous with Earth's carrying capacity, a /36.
> If we handed out /48's instead so each human could give a /64 to each of 
> their devices, it would all fit in a single /52.  Those /48's would 
> number existance at a rate of one /64 per human, one /64 per device, and 
> a 65535:1 device:human ratio.  That means we could allocate 4000::/3 
> just for Earth humans and devices and never need another block for that 
> purpose.
> That's assuming a very high utilisation ratio, of course, but really no 
> worse than IPv4 is currently.  The problem isn't allocation density, but 
> router hardware.  We need room for route aggregation and other means of 
> compartmentalisation.  Is a 10% utilisation rate sparse enough?  At 10% 
> utilisation, keeping the allocations to just 4000::/3, we'd need less 
> than a single /60 for all those /48's.  If 10% isn't enough, we can go 
> quite a bit farther:
> - 1% utilisation would fit all those /48's into a /62.
> - A full /64 of those /48's would be 0.2% utilisation.
> - 0.1%? We'd have to steal a bit and hand out /47's instead.
> - /47 is ugly.  At /52, we'd get .024% (one per 4096).
> That's while maintaining a practice of one /64 per human or device with 
> 65535 devices per human.  Introduce one /64 per subnet and sub-ppm 
> utilisation is possible.  That would be giving a site a /44 and them 
> only ever using the ::/64 of it.
> Even with sloppy, sparse allocation policies and allowing limitless 
> human and device population growth, we very likely can not exhaust IPv6.

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