Re: [v6ops] Stateful SLAAC (draft-ietf-v6ops-unique-ipv6-prefix-per-host)

Fernando Gont <fgont@si6networks.com> Mon, 13 November 2017 14:27 UTC

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Subject: Re: [v6ops] Stateful SLAAC (draft-ietf-v6ops-unique-ipv6-prefix-per-host)
To: Victor Kuarsingh <victor@jvknet.com>
Cc: Lorenzo Colitti <lorenzo@google.com>, "6man@ietf.org" <6man@ietf.org>, "v6ops@ietf.org WG" <v6ops@ietf.org>
References: <be9724f5-2ff5-d90c-2749-ecae2c628b78@si6networks.com> <0b45890d-ea4a-47b8-a650-ceb72b066df8@gmail.com> <ea772bfd-4004-7f94-8469-b50e3aff0f29@si6networks.com> <F2330138-6842-4C38-B5A0-FB40BFACD038@employees.org> <e40697ca-8017-c9d2-c25d-89087046c9cf@gmail.com> <207f040a-7fe2-9434-e7a5-f546b26fdf63@strayalpha.com> <CAKD1Yr26NK2osApYZBm8Yd=0X7xcetrxojp6=JHOEAu9BB0q8A@mail.gmail.com> <8ca59610-2d25-2be4-9d2c-9b1a75fd3ace@si6networks.com> <E67105A3-396B-403C-B741-E9E01CFB5CE7@employees.org> <e7ec4633-8d45-1cff-ce37-48dafd488e13@si6networks.com> <BBAB48C0-384B-4380-9359-7965C7C61D58@employees.org> <4b7e8e53-ea7a-f84d-92cf-a9a113c200ce@si6networks.com> <CAKD1Yr1NG93Jv7E6hKY4BKApwJg6uG0wAgUL74cw1Fb5VsKnUg@mail.gmail.com> <14d489ec-0b28-8fe5-e28c-35a1f4fc15de@si6networks.com> <CAJc3aaPb8vOxfUVk-6sQNGpftegPCgb+j3OyGD55rmCado+VZw@mail.gmail.com> <a4a380b0-d69c-1c2c-fedc-0a3da2a8060a@si6networks.com> <CAJc3aaPg=qOpiwJ29Bq92m2RfZ-VDJtLWb-GgZV7bXP6iELiRA@mail.gmail.com>
From: Fernando Gont <fgont@si6networks.com>
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Date: Mon, 13 Nov 2017 22:29:06 +0800
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On 11/13/2017 10:17 PM, Victor Kuarsingh wrote:
> On Mon, Nov 13, 2017 at 8:51 AM, Fernando Gont <fgont@si6networks.com>; wrote:
>> On 11/13/2017 09:35 PM, Victor Kuarsingh wrote:
>>> On Mon, Nov 13, 2017 at 8:20 AM, Fernando Gont <fgont@si6networks.com>; wrote:
>>>> On 11/13/2017 07:14 PM, Lorenzo Colitti wrote:
>>>>> On Mon, Nov 13, 2017 at 6:21 PM, Fernando Gont <fgont@si6networks.com
>>>>> <mailto:fgont@si6networks.com>> wrote:
>>>>>
>>>>>     >From a operational point of view, one would wonder why pursue this path
>>>>>     as opposed to e.g. do DHCPv6
>>>>>
>>>>>
>>>>> As for DHCPv6 specifically, one reason is that DHCPv6-only networks are
>>>>> not recommended by the IETF. RFC 7934.
>>>>
>>>> Yes, sorry: I meant DHCPv6-PD.
>>>>
>>>> RFC7934:
>>>>
>>>>     Due to the drawbacks imposed by requiring explicit requests for
>>>>     address space (see Section 4), it is RECOMMENDED that the network
>>>>     give the host the ability to use new addresses without requiring
>>>>     explicit requests.  This can be achieved either by allowing the host
>>>>     to form new addresses autonomously (e.g., via SLAAC) or by providing
>>>>     the host with a dedicated /64 prefix.  The prefix MAY be provided
>>>>     using DHCPv6 PD, SLAAC with per-device VLANs, or any other means.
>>>>
>>>> Therefore, why re-invent PD in SLAAC?
>>>
>>> PD is quite vast, and this draft describes a specific set of use
>>> cases.  It does not seem like a re-invention of PD in SLACC to me.
>>
>> Again: Why not use DHCPv6-PD?
>>
> 
> I would leave this up to the operators to decide.

We are the ones trying to make SLAAC stateful, contributing to IPv6
automatic configuration complexity, and apparent lack of coherence with
respect to which protocol supports both, and why we e.g. disregard the
work of other WGs (e.g. dhc).

If you want to *partially* duplicate functionality in another protocol,
please provide a rationale, or don't.



> They are designing
> their network and know their requirements best.

Exactly: nobody specified the requirements, or said why DHCPv6-PD
doesn't fullfill them.



> There are many factors the weigh into why operators make certain
> decisions.  There are circumstances were DHCPv6-PD would be quite
> valid, and others, as described in the draft, where the methods
> described are desirable.  I don't think there is any one way to build
> a network (I am yet to have built two that look exactly the same given
> different input requirements).

You still have not answered my question.

-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492