IPv6 Addressing Help

Mark Andrews marka at isc.org
Fri Aug 14 17:05:49 CDT 2009

In message <4A85878A.2000208 at uk.clara.net>, David Freedman writes:
> Chris Gotstein wrote:
> > I think we had to let ARIN know the time frame of deploying IPv6 and how
> > many customers we expected to put on in the first couple years.  They
> > did not ask for an addressing scheme.
> > 
> > Reading over the RFC's and other IPv6 resources, we have decided to hand
> > out /56's to small/home/SOHO customers and /48's to larger customers.
> > 
> > I'm just not able to wrap my brain around the subnetting that needs to
> > be done on the router.  Like i said before, i think i'm just over
> > complicating it in my mind.
> Will keep it simple, this is what I (and I suspect many others) do
> /128 - Loopback (what else?)
> /126 - Router p2p
> /112 - Router LAN shared segments (p2mp)
> /64  - Single customer LAN segments (customers asking for basic IPv6)
> /56  - Customer wants multiple LANs, doesn't want to fill out
> justification form
> /48  - Customer wants multiple LANs, thinks /56 is too small (for some
> reason), needs for routing, wants rDNS delegation etc.etc.etc..

Why do you think only /48 customers will want reverse DNS?  Every
customer will want reverse DNS.  The question is who supplies the

With the home market potentially getting routable address to all
machines there will also be a need to supply forward DNS services
as well.

> This question gets asked so many times now, whilst people argue about
> the implications of using networks smaller than /64 for anything
> such deployments continue to exist and are successful.
> Perhaps we should document people's addressing plans somewhere, I
> see ratemyaddressingplan.com hasn't been taken yet? :)
> Dave.
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org

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