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Re: IPv6 end user addressing
From: Mark Andrews <marka () isc org>
Date: Tue, 09 Aug 2011 00:18:57 +1000


In message <174561.1312807412 () turing-police cc vt edu>, Valdis.Kletnieks () vt edu
 writes:
--==_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 () isc org


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