Re: [v6ops] FW: Can you please review and comment on draft-xiao-v6ops-nd-deployment-guidelines

Gert Doering <> Sun, 24 October 2021 11:49 UTC

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Date: Sun, 24 Oct 2021 10:07:49 +0200
From: Gert Doering <>
To: Xipengxiao <>
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Subject: Re: [v6ops] FW: Can you please review and comment on draft-xiao-v6ops-nd-deployment-guidelines
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On Sat, Oct 23, 2021 at 07:26:12PM +0000, Xipengxiao wrote:
> > 2. I expect a lot of objections to UPPH. It really is a ridiculous 
> > waste of address space, unless we can reduce the subnet size with a 
> > prefix greater than /64, and that seems very difficult in the IETF.
> [XX] While I acknowledge that giving each host a /64 may seem wasteful, 
> in reality it may not be so bad, for 2 reasons (1) I heard that RIR will 
> give /29 to an applicant without requiring special justification. This 
> will provide 2**35=32 billion /64's - more than enough I would think 

The /29 is intended to number many individual customers.  ISPs are giving
/56s out of this to "SOHO" customers, and /48s to "business customers".

You can't assume that these are all free to be burned in arbitrary numbers 
of /64s on wifi deployments.

(I, for one, will never ever deploy technology that will require me
to allocate something like a /54 to a wifi network, just to be able
to serve 1000 mobile clients [/54 = 2^10 = 1024 /64s] - which is not 
even very large for a corp wifi)

> (2) We are giving a /64 to each mobile phone.  If we can afford
> that in this scenario (with by far the largest number of hosts),
> we should be able to afford that in other scenarios (with smaller
> number of hosts).  Do you agree?

This is totally not comparable, as there are many layers of address
not involved here.  Mobile ISPs get the /29 "all for themselves",
and the way stuff attaches to the mobile network is way different
from the way wifi segments are attached to normal building networks.

(I like the idea of being able to delegate a /96 with DHCPv6-PD to
each device, to appease Lorenzo and finally be done with the everlasting
DHCPv6 vs. Android discussion - but the numbers for /64 are really
not working out)

Gert Doering
        -- with some experience in address space & vs. aggregation math
have you enabled IPv6 on something today...?

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