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

Brian E Carpenter <> Sun, 24 October 2021 19:29 UTC

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To: Xipengxiao <>, Gert Doering <>
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From: Brian E Carpenter <>
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Date: Mon, 25 Oct 2021 08:29:14 +1300
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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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> But the fact is we give each mobile phone is /64 today, and each RG (resident gateway) a /56.  So giving a host a /64 is already a widely existed current practice.   

Note that if a mobile device (maybe not a phone!) is acting as a local hotspot, it needs a prefix, not an address, and /64 is the longest prefix that respects the current addressing architecture. Even that does not allow subnetting.

    Brian Carpenter
    Thinking of the IETF standards process:

On 25-Oct-21 05:04, Xipengxiao wrote:
> Hi Gert,
> Thank you for your time to review and comment.  Please see my response in line.
>> -----Original Message-----
>> From: Gert Doering []
>> Sent: Sunday, October 24, 2021 10:08 AM
>> To: Xipengxiao <>
>> Cc:;
>> Subject: Re: [v6ops] FW: Can you please review and comment on draft-xiao-
>> v6ops-nd-deployment-guidelines
>> Hi,
>> 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".
> [XX] A business Wi-Fi deployment can be considered as a " business customer", and be given a /48 as you suggest. This will allow 64K hosts if each host gets a /64.  Seems like a reasonable arrangement to me.
>> 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)
> [XX] Your opinion is respected.  But the fact is we give each mobile phone is /64 today, and each RG (resident gateway) a /56.  So giving a host a /64 is already a widely existed current practice.
>>> (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.
> [XX] First our draft is not specific to Wi-Fi.  Second, why giving a host a /64 or not depends on " the way stuff attaches
> to the network"?
>> (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)
> [XX] I have no problem with what you suggested, but that's a different discussion.  Please note that our draft didn't prescribe any new solution (or advocate giving each host a /64).  All it did was reviewing the existing ND issues and solutions, and suggested how to select a solution based on the deployment scenario.
> Thanks again for your time.  It's appreciated!
> XiPeng
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