[tram] Adam Roach's Discuss on draft-ietf-tram-stun-pmtud-10: (with DISCUSS and COMMENT)
Adam Roach <adam@nostrum.com> Sun, 30 September 2018 21:19 UTC
Return-Path: <adam@nostrum.com>
X-Original-To: tram@ietf.org
Delivered-To: tram@ietfa.amsl.com
Received: from ietfa.amsl.com (localhost [IPv6:::1]) by ietfa.amsl.com (Postfix) with ESMTP id DC4B6129619; Sun, 30 Sep 2018 14:19:30 -0700 (PDT)
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
From: Adam Roach <adam@nostrum.com>
To: The IESG <iesg@ietf.org>
Cc: draft-ietf-tram-stun-pmtud@ietf.org, Gonzalo Camarillo <gonzalo.camarillo@ericsson.com>, Tolga Asveren <tasveren@rbbn.com>, tram-chairs@ietf.org, tasveren@rbbn.com, tram@ietf.org
X-Test-IDTracker: no
X-IETF-IDTracker: 6.84.0
Auto-Submitted: auto-generated
Precedence: bulk
Message-ID: <153834237082.13405.1228259718885034461.idtracker@ietfa.amsl.com>
Date: Sun, 30 Sep 2018 14:19:30 -0700
Archived-At: <https://mailarchive.ietf.org/arch/msg/tram/QdwF3D_wMPjx2pFsUtrSYxAU1HU>
Subject: [tram] Adam Roach's Discuss on draft-ietf-tram-stun-pmtud-10: (with DISCUSS and COMMENT)
X-BeenThere: tram@ietf.org
X-Mailman-Version: 2.1.29
List-Id: "Discussing the creation of a Turn Revised And Modernized \(TRAM\) WG, which goal is to consolidate the various initiatives to update TURN and STUN." <tram.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tram>, <mailto:tram-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tram/>
List-Post: <mailto:tram@ietf.org>
List-Help: <mailto:tram-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tram>, <mailto:tram-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 30 Sep 2018 21:19:31 -0000
Adam Roach has entered the following ballot position for draft-ietf-tram-stun-pmtud-10: Discuss When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-tram-stun-pmtud/ ---------------------------------------------------------------------- DISCUSS: ---------------------------------------------------------------------- This seems like an interesting technique that warrants collection of operational experience. >From a process perspective, I think we have a bit of an issue, unless I've overlooked something relevant. This is proposed as a Standards-Track document, but it relies on the use of the PADDING attribute defined in RFC 5780. RFC 5780 is Experimental, so this is a formal downref. And RFC 5780 does not appear in the downref registry [1], nor did the IETF last call [2] include a request that the IETF community consider allowing such a refernce. >From a practical perspective, the mechanism described in this document seems like the kind of thing that it would be useful to gather operational experience with prior to putting it on the standards track. I have some operational concerns (described below) that I think could be either proven out or dispelled by experimental deployment of the technology. My recommendation is to recategorize this mechanism as experimental, adding some text about the desire to gather operational experience. For avoidance of doubt: My DISCUSS is only on the process issue, and I'll happily clear regardless of how this issue is rationalized (e.g., either by running IETF last call again, by reclassifying this mechanism as experimental, or perhaps some novel solution that I may not have thought of). Everything else is merely a recommendation. ____ [1] https://datatracker.ietf.org/doc/downref/ [2] https://www.ietf.org/mail-archive/web/tram/current/msg02609.html ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- In the general case, STUN servers aren't aware of the signaling protocol that is in use. For example, when a TURN server is use with RTP and RTCP with a session set up via SIP, there is no requirement that the TURN server itself have any inherent knowledge of SIP or RTP or RTCP. From that perspective, the following text in section 4.2 is a bit confusing and/or problematic: Some application layer protocols may already have a way of identifying each individual UDP packet, in which case these identifiers SHOULD be used in the IDENTIFIERS attribute of the Report Response. It seems odd that I would have to teach my TURN server about the protocols I'm using it with just so that it can identify the packets. This behavior, combined with the requirement that all behavior be symmetrical ("As a result of the fact that all endpoints implementing this specification are both clients and servers") leads me to believe that perhaps the use cases that drove this mechanism are tightly scoped to direct peer-to-peer uses of ICE, while the other common uses of STUN (e.g., public TURN servers used for symmetric NAT traversal) were given no consideration. If that was intentional, then I think the abstract and introduction need to clearly describe the scenarios the mechanism was defined for; and, more importantly, clarify that it does not work for the general case, including STUN servers used for NAT traversal. I suspect that, once this mechanism begins to be deployed, the foregoing limitations will cause operational difficulties, which may in turn suggest changes to the mechanism that is currently defined, hence my suggestion above to recharacterize the mechanism as experimental. --------------------------------------------------------------------------- §4: > The Probing mechanism is used to discover the Path MTU in one > direction only, from the client to the server. Nit: "...only: from..." > Two Probing mechanisms are described, a Simple Probing mechanism and Nit: "...described: a Simple..." > a more complete mechanism that can converge quicker and find an Nit: "...converge more quickly..." > appropriate PMTU in the presence of congestion. Additionally, the Nit: Please expand "PMTU" on first use. --------------------------------------------------------------------------- §4.2.5: > algorithm used for the FINGERPRINT attribute (i.e., the CRC-32 of the > payload XOR'ed with the 32-bit value 0x5354554e [ITU.V42.2002]). The location of the citation in here implies that the XOR'ing described is part of V.42. Given that 0x53545554E is ASCII for "STUN," I'm pretty sure that's not part of the underlying CRC. Would suggest reworking as: algorithm used for the FINGERPRINT attribute (i.e., the CRC-32 calculated per the algorithm defined in [ITU.V42.2002], such has subsequently been XOR'ed with 32-bit value 0x5354554e).
- [tram] Adam Roach's Discuss on draft-ietf-tram-st… Adam Roach
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Spencer Dawkins at IETF
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Simon Perreault
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Spencer Dawkins at IETF
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Simon Perreault
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Spencer Dawkins at IETF
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Camarillo
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Spencer Dawkins at IETF
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Salgueiro (gsalguei)
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Camarillo
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Salgueiro (gsalguei)
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Camarillo
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Camarillo
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Salgueiro (gsalguei)
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Camarillo
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Gonzalo Salgueiro (gsalguei)
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Felipe Garrido (fegarrid)
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Felipe Garrido (fegarrid)
- Re: [tram] Adam Roach's Discuss on draft-ietf-tra… Adam Roach