IPv6 end user addressing

Mark Andrews marka at isc.org
Mon Aug 8 14:18:57 UTC 2011

In message <174561.1312807412 at turing-police.cc.vt.edu>, Valdis.Kletnieks at vt.edu
> --==_Exmh_1312807411_38980P
> Content-Type: text/plain; charset=us-ascii
> On Mon, 08 Aug 2011 10:15:17 +0200, Mohacsi Janos said:
> > - Home users - they usually don't know what is subnet. Setting up 
> > different subnets in their SOHO router can be difficult. Usually the 
> > simple 1 subnet for every device is enough for them. Separating some 
> > devices into  a separate subnets is usually enough for the most 
> > sophisticated home users. If  not then he can opt for business service....
> You don't want to make the assumption that just because Joe Sixpack doesn't
> know what a subnet is, that Joe Sixpack's CPE doesn't know either.
> And remember that if it's 3 hops from one end of Joe Sixpack's internal net t
> o
> the other, you're gonna burn a few bits to support heirarchical routing so yo
> u
> don't need a routing protocol. So if Joe's exterior-facing CPU gets handed a
> /56 by the provider, and it hands each device it sees a /60 in case it's a
> device that routes too, it can only support 14 devices.  And if one of the
> things that got handed a /60 is a wireless access point or something, it's on
> ly
> going to be able to support 15 or so subnets. So a simple topology of only a
> half dozen devices can burn up 8 bits of subnet addressing real fast. Yes, yo
> u
> can conserve bits by being more clever, but then you probably need an IGP of
> some sort....

Which is why CPE devices shouldn't do heirarchical assignment by default.
PD supports multiple upstream requests.  

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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