IETF Logo Mail Archive

Re: [Taps] New rev of udp-usage (01) and review comments on taps-transport-usage-04

Joe Touch <touch@isi.edu> Mon, 15 May 2017 19:14 UTC

Return-Path: <touch@isi.edu>
X-Original-To: taps@ietfa.amsl.com
Delivered-To: taps@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id DACD11201F8 for <taps@ietfa.amsl.com>; Mon, 15 May 2017 12:14:50 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -5.001
X-Spam-Level:
X-Spam-Status: No, score=-5.001 tagged_above=-999 required=5 tests=[BAYES_40=-0.001, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_HI=-5, RP_MATCHES_RCVD=-0.001] autolearn=ham autolearn_force=no
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 tptCQB6EYcaR for <taps@ietfa.amsl.com>; Mon, 15 May 2017 12:14:49 -0700 (PDT)
Received: from vapor.isi.edu (vapor.isi.edu [128.9.64.64]) (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 F2E32128E19 for <taps@ietf.org>; Mon, 15 May 2017 12:11:37 -0700 (PDT)
Received: from [128.9.184.22] ([128.9.184.22]) (authenticated bits=0) by vapor.isi.edu (8.13.8/8.13.8) with ESMTP id v4FJAgp9006048 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT); Mon, 15 May 2017 12:10:43 -0700 (PDT)
To: Michael Welzl <michawe@ifi.uio.no>, "<gorry@erg.abdn.ac.uk> Fairhurst" <gorry@erg.abdn.ac.uk>
Cc: "taps@ietf.org" <taps@ietf.org>
References: <15106817-a81c-d247-5fad-a67c5faa93f3@erg.abdn.ac.uk> <8A063CAE-55DF-4C38-8631-DC854564DE22@ifi.uio.no>
From: Joe Touch <touch@isi.edu>
Message-ID: <46d4da5d-8e64-2d9b-fcda-c822d88469d7@isi.edu>
Date: Mon, 15 May 2017 12:10:40 -0700
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0
MIME-Version: 1.0
In-Reply-To: <8A063CAE-55DF-4C38-8631-DC854564DE22@ifi.uio.no>
Content-Type: multipart/alternative; boundary="------------2F3200DF8F9857C05BA1B36F"
Content-Language: en-US
X-ISI-4-43-8-MailScanner: Found to be clean
X-MailScanner-From: touch@isi.edu
Archived-At: <https://mailarchive.ietf.org/arch/msg/taps/vNLivKmdQzEUjtnrU3n7LwsMVyU>
Subject: Re: [Taps] New rev of udp-usage (01) and review comments on taps-transport-usage-04
X-BeenThere: taps@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Discussions on Transport Services <taps.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/taps>, <mailto:taps-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/taps/>
List-Post: <mailto:taps@ietf.org>
List-Help: <mailto:taps-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/taps>, <mailto:taps-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 15 May 2017 19:14:51 -0000

FWIW:


On 5/12/2017 5:31 AM, Michael Welzl wrote:
>> -------------------
>> Get Interface MTU is missing from pass 2 and 3:
>>
>> ADD to pass 2:
>>
>> 	GET_INTERFACE_MTU.UDP:
>> 		Pass 1 primitive: GET_INTERFACE_MTU
>> 		Returns: Maximum datagram size (bytes)
> But this doesn’t exist!  It’s strictly an IP function and I couldn’t find it described for UDP anywhere. I think we agreed on how a TAPS system should handle this, and this is reflected in
> https://tools.ietf.org/html/draft-gjessing-taps-minset-04#section-6.4.1
> … which may require a system to implement new local functionality, maybe based on this MTU function - but to my understanding it’s just not something that UDP offers.
IP is supposed to export MMS_S and MMS_R to the transport, which are
calculated from EMTU_S, EMTU_R, and the link MTU for the given source IP
address.. PMTUD exports PMTU to the transport. Both already take into
account the link MTU and other MTU information, where available.

In no cases does the transport actually ever need to see the link MTU.

Joe

v2.23.0 | Report a Bug | By Email