Waste will kill ipv6 too

Mark Andrews marka at isc.org
Fri Dec 29 04:36:51 CST 2017


> On 29 Dec 2017, at 2:51 pm, valdis.kletnieks at vt.edu wrote:
> 
> On Thu, 28 Dec 2017 20:26:46 -0700, Brock Tice said:
> 
>> I will again say I am indeed no expert, I am happy to get feedback. Is
>> there some kind of allocation scheme where a residential user or even a
>> small or medium business will have any chance of using 4096 /64s?
> 
> They won't burn 4096 consecutive addresses.  They'll do what you said - your
> gear supplies their head-end router a /52.  That then starts handing out a
> half-dozen or so /64s for hardware interfaces, and hands a DHCP-PD /56 to the
> expansion router at the other end of the house, which then hands out a
> half-dozen /64s for subnets at that end, and *it* then hands a /60 PD to the
> garage and barn routers, so they can each set up a half-dozen /64s.

PD is designed so that a device (router) can request multiple PD requests upstream. The interior router just needs to make a upstream request on behalf of the downstream device and any prefixes it will be allocating itself.  There is zero need to maintain a pool of prefixes to answer prefix requests.   If you get back a bigger (e.g. /48 sized response) you just use those until they have all been handed out.

> So yeah, they need a /52, even though we've only burned through 2 or 3 dozen
> /64s.  But this is the way it's *supposed* to work - note that careful choice of
> subnet numbers for the PD and local subnets means that even if other stuff
> shows up and starts asking for a PD, there will be plenty left for them to use.

-- 
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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