[Taps] Drive-by comments on draft-fairhurst-taps-transports-usage-udp-01

worley@ariadne.com (Dale R. Worley) Wed, 06 April 2016 15:23 UTC

Return-Path: <worley@alum.mit.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 63A8F12D660 for <taps@ietfa.amsl.com>; Wed, 6 Apr 2016 08:23:27 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.934
X-Spam-Level:
X-Spam-Status: No, score=-1.934 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_SOFTFAIL=0.665] autolearn=no autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=comcast.net
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 GPzP4svxPRKV for <taps@ietfa.amsl.com>; Wed, 6 Apr 2016 08:23:26 -0700 (PDT)
Received: from resqmta-ch2-01v.sys.comcast.net (resqmta-ch2-01v.sys.comcast.net [IPv6:2001:558:fe21:29:69:252:207:33]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id BFDA112D11F for <taps@ietf.org>; Wed, 6 Apr 2016 08:19:55 -0700 (PDT)
Received: from resomta-ch2-16v.sys.comcast.net ([69.252.207.112]) by comcast with SMTP id npF5abxHwVEtunpFLaj0Rv; Wed, 06 Apr 2016 15:19:55 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1459955995; bh=mDBvAFUSWFEJr9uPnZ1mNDrXE4/tTU3YLdmsIENMgtM=; h=Received:Received:Received:Received:From:To:Subject:Date: Message-ID; b=JS4uSZZ1eZNw/IHmGx7GWPxlQp4RejxZ5HHDlxCv854f+RpCIOKGXHE0WiFB35FuO 33xHHdWPYIgmqau1atMwkfKp+p9kZaVaK870Hdop3AxWtedxtUJDZ/OMgZC0XAi2d4 mHPZkbS/ZigJsttVBIhvYlgpmuQX1p8pE0+MqSqIzXUEyypfL8V4ypglCOd/p+l69/ 6vWyzerqvmmB1KVDcsMeyUAxIWVMiRRCDUK112Ry/jXQO/X75HW4HtH0L2nXJomlpN IJleJpzxc7rS9u2eQaEcg3RlobbWB4k2Q1evo69uYweKPltmPtHJVlCuIVR0JMQXWD ygrPA7c0EH9PQ==
Received: from hobgoblin.ariadne.com ([73.143.237.82]) by resomta-ch2-16v.sys.comcast.net with comcast id f3Ku1s0071nMCLR013KuSX; Wed, 06 Apr 2016 15:19:55 +0000
Received: from hobgoblin.ariadne.com (hobgoblin.ariadne.com [127.0.0.1]) by hobgoblin.ariadne.com (8.14.7/8.14.7) with ESMTP id u36FJrCT013663 for <taps@ietf.org>; Wed, 6 Apr 2016 11:19:53 -0400
Received: (from worley@localhost) by hobgoblin.ariadne.com (8.14.7/8.14.7/Submit) id u36FJrnF013656; Wed, 6 Apr 2016 11:19:53 -0400
X-Authentication-Warning: hobgoblin.ariadne.com: worley set sender to worley@alum.mit.edu using -f
From: worley@ariadne.com
To: taps@ietf.org
Sender: worley@ariadne.com
Date: Wed, 06 Apr 2016 11:19:53 -0400
Message-ID: <877fgawyqu.fsf@hobgoblin.ariadne.com>
Archived-At: <http://mailarchive.ietf.org/arch/msg/taps/bimJvqS3p0o_CllEBB8F0kFJBnQ>
Subject: [Taps] Drive-by comments on draft-fairhurst-taps-transports-usage-udp-01
X-BeenThere: taps@ietf.org
X-Mailman-Version: 2.1.17
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: Wed, 06 Apr 2016 15:23:27 -0000

I'm reading parts of draft-fairhurst-taps-transports-usage-udp-01
because it was presented in the Dispatch session of the meeting, so I
don't have all the context for this draft.  But a couple of comments
struck me:

The description seems to be connection-oriented, in that it only
describes usages involving two endpoints establishing a connection and
then using it.  Indeed, even the process of establishing a listening
port based on which connections will be created is not described.  E.g.,
the description of the CONNECT primitive says "The CONNECT primitive
allows the association of source and port sets to a socket ...", but
doesn't describe where the socket comes from, or that packets can arrive
on a socket before the receiver has done a CONNECT.

Perhaps these concepts are discussed in the document that establishes
the framework for this draft.  At the least, the use of listening ports
needs to be formalized.

In section 3.1 is:

   SET_IPV6_UNICAST_HOPS:  The SET_IPV6_UNICAST_HOPS function sets the
      hop limit field to be used in the field of an IPv4 header of a
      packet that carries an UDP datagram.  For IPv6 unicast datagrams,
      this is functionally equivalent to the SET_TTL IPv4 function.

   GET_IPV6_UNICAST_HOPS:  The GET_IPV6_UNICAST_HOPS function reads the
      value from the hop count field in the IPv6 header of a received
      UDP datagram.  For IPv6 unicast datagrams, this is functionally
      equivalent to GET_TTL IPv4 function.

I might be wrong, but it looks like "IPv4" and "IPv6" are mistaken for
each other in three places in these items.

How does the application get notified that a packet has arrived?  The
only event that is defined is ERROR_REPORT.  The RECEIVE primitive is
called by the application, but application has to first know that there
is a packet to receive.

Dale