nanog mailing list archives

Re: Waste will kill ipv6 too


From: Mark Andrews <marka () isc org>
Date: Fri, 29 Dec 2017 15:36:51 +1100


On 29 Dec 2017, at 2:51 pm, valdis.kletnieks () 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 () isc org


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