[dhcwg] A late review of draft-ietf-dhc-slap-quadrant-09

Tomek Mrugalski <tomasz.mrugalski@gmail.com> Mon, 08 June 2020 13:10 UTC

Return-Path: <tomasz.mrugalski@gmail.com>
X-Original-To: dhcwg@ietfa.amsl.com
Delivered-To: dhcwg@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id F27D63A0A84 for <dhcwg@ietfa.amsl.com>; Mon, 8 Jun 2020 06:10:50 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.099
X-Spam-Level:
X-Spam-Status: No, score=-2.099 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JMFQdl-e5Vws for <dhcwg@ietfa.amsl.com>; Mon, 8 Jun 2020 06:10:49 -0700 (PDT)
Received: from mail-lj1-x22a.google.com (mail-lj1-x22a.google.com [IPv6:2a00:1450:4864:20::22a]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id DA7F83A0A5E for <dhcwg@ietf.org>; Mon, 8 Jun 2020 06:10:48 -0700 (PDT)
Received: by mail-lj1-x22a.google.com with SMTP id x18so3914946lji.1 for <dhcwg@ietf.org>; Mon, 08 Jun 2020 06:10:48 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:subject:autocrypt:to:message-id:date:user-agent:mime-version :content-language:content-transfer-encoding; bh=Uy0qo4oHf9WuG7nK0taAPX4M9aFaxCEiibOhZ8qQMDM=; b=Oh51TgSeh/8gV/Kj9ZerjPHV4tQOzNv5IQw3qIiuKlNttNudAsOtQITJJu9DwVsus1 pkpWFlz0OLcOSkPwjJQd/859R6f666HoN8PJsa9KTs8JGSJLl2abi/wYOpcCPV3zjhe5 /J9tMlI6safeBhoKaUe7Udg0JTdT2VCFh5JVBLTttB6gFn8V4hBYM4hj8X5L/Qjmgwcb pSBbC5KDdv+WKlGItyECcqgIAw/mgF6K9w8cmS4Hhcm3k1sPpVrZIWhgRb3twrr5SpDM TQpTR2XhduXGQ2D/DIULFHz5fUR9AvZ3Gktp36+CMb2Ay7vvvhjwXb2zlk16Q4xZPf4G 0SJA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:autocrypt:to:message-id:date :user-agent:mime-version:content-language:content-transfer-encoding; bh=Uy0qo4oHf9WuG7nK0taAPX4M9aFaxCEiibOhZ8qQMDM=; b=jsOy9ZY/YsDCsLm3yIKLS9S8ougFWKDwta7YZJH7w4ohm2jfeyg47+6ncdMqkVgKZh K/4sq6dlnxRuYBDmjbz0siuXwtk/DtYgbdqKKqTlfzt/sD8bSB3yHNKvotCC2HLqeQ7J D0VKpEwx2cDeEIh7BeBoEEiTB7UARNTZOVTPiCgtddLdfkYmf6R1ou9/Q2HQctXhsBgA 74UHPAj6V4KQj3sk7wiABFNlv4dgf5nRBw0NVWbc0y4NTXdPt+Y05ZizHk9/r2cPdiwY bIMDOlKqO5t9/uLeAZdyh7dMP4JRv2lC3wVoacPr6EGA5ytlxxUFW9iaeaC6OI2J7JTV k6qA==
X-Gm-Message-State: AOAM532gIwQ7Kg8x8C/lvRbbp+8Gt/cGZobmK7/QBIhfTqEPZCnhlkyC ttFfxp3JVFCl8wrjOCMZ+vB2uAYJ
X-Google-Smtp-Source: ABdhPJweyZtl1Lr7IG5cnz+yLpNRuP/L2uYvYSbzOqVwp1VR3Em4sAIoJSDo2sM0b7GwT1DAi4aHKw==
X-Received: by 2002:a2e:7105:: with SMTP id m5mr983391ljc.79.1591621846481; Mon, 08 Jun 2020 06:10:46 -0700 (PDT)
Received: from [192.168.1.78] ([31.134.62.65]) by smtp.gmail.com with ESMTPSA id 10sm3679712ljw.134.2020.06.08.06.10.45 for <dhcwg@ietf.org> (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 08 Jun 2020 06:10:45 -0700 (PDT)
From: Tomek Mrugalski <tomasz.mrugalski@gmail.com>
Autocrypt: addr=tomasz.mrugalski@gmail.com; prefer-encrypt=mutual; keydata= mQINBFnoiMwBEADTmiPRnreg9BKxRAq5IixkTT6sMqpueC9kf3UGP3KAeO032wLkEdLd/ELW bhXv2Z0k2Jeq8N9qSsn0uiwlizPz1trH/lad/xQolv6529jhMdWvpt9iNpmjY/M0bdwG8E3e pSpYLg2p9TSa/N3XOIJYqcMHlWaqTlU+//5w2KXQd585+X68bfWmLJQvA371kUAp75PzwHJt zmL6SI5jZOhONPrisUnvEic1cW/VVLQ0RUc6O9+fmpyzoDKKXO/mKxjXScyE7hGmZI2Yr3X5 bf+wixXRnM6mYSocRbMYtPSotWo9UNRQCM3ns4Q8wf99Hbpy0kdLL3aD1NdgdJbIDcbONBj4 YX0bDiaWMKBuUsbBXe1wEUsmkwYxFSdKKJGiOQpDaOFSbiyn0HXAjj9iOcEOSjls03RHS0RV F59Ra0HTaIQIoqgPimjzZK3D7Yee8UKgzNQ/kvowJvom2H+GI6c4YXhluyDE1k869V/EIRO/ kxyznUaXT1kgD+v8YZESm/s5JG6gPYf2Whxp4zW0mRwJE1nJWUdrR/T5aYJatBhwdiYqhOzt qJm6HRihoAz7DxebsVtv/pH/EdX9K0yMdjw4y9cElrXQkUa5jFiPk5fhYcJFp1lxcMy+IZps FR4JUYUkB2gEKbLRp3o7g3PlA1DmeGOv3ojMAWOw9l1l9UDxHwARAQABtCxUb21layBNcnVn YWxza2kgPHRvbWFzei5tcnVnYWxza2lAZ21haWwuY29tPokCVAQTAQgAPhYhBBGZCpIDRNb+ ndZDaYPU7qyYlWHJBQJeoEvyAhsjBQkJZgGABQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAAoJ EIPU7qyYlWHJQ2cQAKQ1EwcjxZCpqPmyBBtIzmGKEo5hU+W1t1/fuzSVPbfXA5gjkOkFcet+ PINaYSPVrn8ahZcclgklZHrIrCDIs1u0ynHteyDii13AWOpU6ksXp6W3fLI7iW/BY1xqnZS/ MC26fZkUZ+8Tw/OdvI0Fqtimkkvr1lA7qx8lMB95q0NwkLRxbRudZF2ln0Dde3KXL1Ku9YLG v5FTRC1P77r7AzmiFhuAc4U+4IVTVoECkHV3EXBckctO78fWPAn9Q9Qp+w5fZU+zYOcqhHxV 1AmWRxhscyaJcQLaDVd9A4ltjj4Bvk4/H5hNZlC1tP6MI+kF0/scL5hW5NYi26XV8MyjWJns Z8o1w/D4LU8sl/NoKIuZ6D4zDXRmVDEHhP+ahuUwgleUvsZNsSlwcNszQRDa7H9CzUOMWIfE kcH2vB6esqwWdt6HgZbPRWGAuim21VvjnVphbko553VgO3Lk61f9eKsu9wnwD8/5je9tTFte 5wO9pWYbZckBUBlPquEnqcTxO6pa6519t/JIfP1Bb/CJbcGwaAO+v1QxdsIcieZ38PoHhDOp GgSRSPuI0DEgKlt93AKj5Ja08OtzHqKJ+j9ESCITgc443qJKt4+huK7L3Dhw2uoAy4ZLq21m D0irW5/Ddqkc5bAwOGMOn4t5hsKTgUA45RDQw6M+kbkAfn/pAcn4uQINBFnoiMwBEADBPSEG UwIayl//i6LJWoy+xJaMSdsiCvcIKcUUSFFRPvbpJ5vYeqoVVRr+EvobpwEYeoy9MGGXamPO 6jC8E2Ufq/pxZAof5x7Kt5GYs/qEgbJyLvQ+Fc9PADhfoJAZQU5Jm/oQ8lIl0CLPmIv62jtY lAPesK/YjPYoFzdQfS9jOVso/WJrYVkKIG3+0RN8LOonR82Z1NIm1TXDuXVDLjLAr+M0k3UZ wviup3eT/lh6xJkTSg8/+DXIWv0SNtEkvNjxZPQwPB9WuvtqD/5SVR7QJifyqqq9T0EovFg0 KHZognMPqIKiYfuZ7SGFHBQZut58Fdg7C9kKwv3QoSwJc9jkMfMw2vcPJUoj41JwATAPSwF2 8Xqa4hBFHZZ/nY3p/3oJOXFW9ubYyf+YrsCbN30FxFN2bCerSZRahb2vkSgibxNjjvemM7Yy uabUFfd5MXqBwS6MzFjeUEI/CWMAxfWWFykMisGT+w+rTAC9/YusuoeEAFldvOrSgN4anmQ8 5CHWGEx3lqNNCLEnhSi9W62MOptfHSGoLLJTz5V2AvGgXX1r4AKhr0upea3ALwXHB41/+wQY PD4uBGQvMb9wFavq3bSglBZ9gvnk+P0EZ2Sfw8BU+AywDJF0PkFwK4on7zLMntgr73B6RNbs IDzWxXEUq1g94PELB9nE7O+zEi7N1wARAQABiQI8BBgBCAAmFiEEEZkKkgNE1v6d1kNpg9Tu rJiVYckFAlnoiMwCGwwFCQlmAYAACgkQg9TurJiVYcmkeg/9Ha9VvXZFUEAEdiKlYJd+nSwd q3QVp5C44EHopblM/AO43OxJREaelc+OPeRo7OaAGtNosLNb1+ocYG6azZjaGyB8UcGXUpKa kqzGapJZxbe5ugiIg2HgWsQx2cshfMLAz00z+gYjVkvvrffJeATnVSRJ3/VDxNfXt1SRNp20 aw2r6FPTkMq+wQYjHKi4rW3NXMnnTVJd3zNepXEdaLl4o5wggOeWePKFN1bTpLZiBTJG7aWT ltrRLzYC1z+4WIutGO1ytQbQV5PDtWncbsbcjtiegpJqNu6q8ThvzvHn1UyP/lx25Sjhgp9/ 5wOwiyDbZbrrNTksNtHkC36ObM9rRw+CfOkf+aTcM+zZB7TUlj924XzuhzqlLQcjuJZ1Tq4f oNz2EeRVDvovZfyhJqO81nNEND4MQi8yumTm4G60IdMPSmJCl4TyIPQJ886h+omcE8hSpbEa MAuV0sLyNKcW3ZgscQqyaeqX3EB3uHhT7cw6NEOkgzyN9tURCMtfnpVGKFA2fSZh1rXhB1yf txOxaBYTw1Wxp2KNDGllsvKOXjz57O9EI4dhqpd+Wl8z+q1jFc5+8g5Fkv8PWvFNF9h2C/kn fNm+qj9w5PCcjkXJEH3imij2e89rWloVAkSQK14sZNuAykzIUSjQv5gpcUPUpNqIJN4G7PqT iVUOrUt+SYc=
To: dhcwg@ietf.org
Message-ID: <2d7c2773-d2b8-d0da-db39-b60d8d21aab6@gmail.com>
Date: Mon, 8 Jun 2020 15:10:44 +0200
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.8.1
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/dhcwg/8rds5O1P1wC8iIllxCEGWGXTftY>
Subject: [dhcwg] A late review of draft-ietf-dhc-slap-quadrant-09
X-BeenThere: dhcwg@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: <dhcwg.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dhcwg>, <mailto:dhcwg-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dhcwg/>
List-Post: <mailto:dhcwg@ietf.org>
List-Help: <mailto:dhcwg-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dhcwg>, <mailto:dhcwg-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 08 Jun 2020 13:10:51 -0000

Hi,
I was requested by IANA to do an expert review of dhc-slap-quadrant-09.
I did as requested and in the process I have reviewed the whole draft.
It's a bit late for editorial changes, but I was not able to dedicate
any time sooner. Sorry for that.

The proposed changes are mostly editorial in nature, except the one
about what the client should do if receives an address from different
quadrant than requested.

Abstract: "A new DHCPv6 option (OPTION_SLAP_QUAD, or QUAD)". Please pick
one name that you want to use for the option and stick with it. Using
alternate names is confusing. I'd prefer to not mention
OPTION_SLAP_QUAD, because that the constant representing a specific
value. The abstract should convey general idea, not the implementation
details.

Section 4.1, bullet 2: "The server, upon receiving an IA_LL option,
inspects its contents. [...] If suitable addresses are found, the server
sends back an Advertise message". This is imprecise. It can easily be
misunderstood as "if there's IA_LL option, always send Advertise,
regardless of if the client sent Solicit, Request or Renew.
This must be rephrased. I suggest something like "The server, upon
receiving an IA_LL option in Solicit, inspects its contents.".

Section 4.1, bullet 5: "When the assigned addresses are about to expire,
the client sends a Renew message." This is usually not true. The client
sends Renew after T1, which usually (as recommended by RFC8415) is set
to 50% of a valid lifetime.

Section 4.1, bullet 6: " 6.  The server responds with a Reply message,
including an LLADDR option with extended lifetime." This can easily be
misinterpreted as "the server sends LLADD as a top-level option in
Reply". This is not true. The LLADDR option is always supposed to be
sent in IA_LL.

"The client SHOULD check if the received MAC address comes from one of
the requested quadrants.  Otherwise, the client SHOULD NOT configure
the obtained address." What if the relay inserted a different an option
asking for a different quadrant and the server's policy used that?
Client following the text as written would drop the option and will not
used the LL address assigned. So how exactly the server policy would
work if anything the client didn't request would be dropped? The policy
could only possible rearrange order of quadrants that the client said is
willing to accept.

I don't particularly like that. There are many mechanisms in DHCPv6
where the client sends some options as hints or suggestions, but it's
not really a negotiation. The server knows best. Would you be willing to
change that, so the client always accepts what the server had said?

If you want the client to pick a different server, you can do so when
evaluating received Advertises. The text as written allows the client
to change his mind when Reply is received.

Section 4.2, bullet 2: "if a client sends multiple instances of the
IA_LL option in the same message, the DHCP relay MUST only add a single
instance of the QUAD option." What if the relay supports this draft,
but isn't configured to insert specific value?

Section 4.2, bullet 9: The same issue as 4.1, bullet 5 (sends renew
when address about to expire).

Section 5.1 "If the server cannot provide an assignment from one of the
specified quadrant-n fields, it MUST NOT assign any addresses and return
a status of NoQuadAvail (IANA-2) in the IA_LL Option." from one => from any.

I support the draft moving forward and I'll pass a note to IANA about my
positive expert review for the option format.

Tomek