Re: [tae] New draft: announcing the supported transports via DNS

"Dan Wing" <dwing@cisco.com> Fri, 18 September 2009 19:06 UTC

Return-Path: <dwing@cisco.com>
X-Original-To: tae@core3.amsl.com
Delivered-To: tae@core3.amsl.com
Received: from localhost (localhost [127.0.0.1]) by core3.amsl.com (Postfix) with ESMTP id 4BBE13A68C8 for <tae@core3.amsl.com>; Fri, 18 Sep 2009 12:06:20 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.217
X-Spam-Level:
X-Spam-Status: No, score=-6.217 tagged_above=-999 required=5 tests=[AWL=-0.218, BAYES_00=-2.599, J_CHICKENPOX_43=0.6, RCVD_IN_DNSWL_MED=-4]
Received: from mail.ietf.org ([64.170.98.32]) by localhost (core3.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8+9AS-fU6TJE for <tae@core3.amsl.com>; Fri, 18 Sep 2009 12:06:19 -0700 (PDT)
Received: from sj-iport-2.cisco.com (sj-iport-2.cisco.com [171.71.176.71]) by core3.amsl.com (Postfix) with ESMTP id 265B23A6915 for <tae@ietf.org>; Fri, 18 Sep 2009 12:06:19 -0700 (PDT)
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: Ap0EADN3s0qrR7MV/2dsb2JhbACKbawKiFABkBUFhBuBXYki
X-IronPort-AV: E=Sophos;i="4.44,411,1249257600"; d="scan'208";a="206189446"
Received: from sj-dkim-1.cisco.com ([171.71.179.21]) by sj-iport-2.cisco.com with ESMTP; 18 Sep 2009 19:07:14 +0000
Received: from sj-core-5.cisco.com (sj-core-5.cisco.com [171.71.177.238]) by sj-dkim-1.cisco.com (8.12.11/8.12.11) with ESMTP id n8IJ7DlY012919; Fri, 18 Sep 2009 12:07:13 -0700
Received: from xbh-sjc-211.amer.cisco.com (xbh-sjc-211.cisco.com [171.70.151.144]) by sj-core-5.cisco.com (8.13.8/8.14.3) with ESMTP id n8IJ7Dxx003348; Fri, 18 Sep 2009 19:07:13 GMT
Received: from xfe-sjc-212.amer.cisco.com ([171.70.151.187]) by xbh-sjc-211.amer.cisco.com with Microsoft SMTPSVC(6.0.3790.3959); Fri, 18 Sep 2009 12:07:06 -0700
Received: from dwingwxp01 ([10.32.240.198]) by xfe-sjc-212.amer.cisco.com with Microsoft SMTPSVC(6.0.3790.3959); Fri, 18 Sep 2009 12:07:06 -0700
From: Dan Wing <dwing@cisco.com>
To: 'Joe Touch' <touch@ISI.EDU>
References: <Pine.LNX.4.64.0909180057060.5479@zippy.stdio.be> <77F0974F-62CD-411C-96D3-C29E6D872DEA@asomi.com> <4AB2E6AB.7020409@gmail.com><4AB3A33B.7080909@ifi.uio.no> <4AB3A5DE.1040708@isi.edu> <055001ca388b$163a0070$5da36b80@cisco.com> <4AB3CF61.5060208@isi.edu> <057601ca388e$d775e620$5da36b80@cisco.com> <4AB3D3ED.5010002@isi.edu> <058401ca3891$8b0e3d20$5da36b80@cisco.com> <4AB3D84E.3090408@isi.edu>
Date: Fri, 18 Sep 2009 12:07:06 -0700
Message-ID: <058b01ca3893$36cad190$5da36b80@cisco.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
X-Mailer: Microsoft Office Outlook 11
Thread-Index: Aco4kiMsPgMSZd7vTwGVMgJ1yDq47wAAEpQA
In-Reply-To: <4AB3D84E.3090408@isi.edu>
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3350
X-OriginalArrivalTime: 18 Sep 2009 19:07:06.0447 (UTC) FILETIME=[36D09DF0:01CA3893]
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; l=3054; t=1253300833; x=1254164833; c=relaxed/simple; s=sjdkim1004; h=Content-Type:From:Subject:Content-Transfer-Encoding:MIME-Version; d=cisco.com; i=dwing@cisco.com; z=From:=20=22Dan=20Wing=22=20<dwing@cisco.com> |Subject:=20RE=3A=20[tae]=20New=20draft=3A=20announcing=20t he=20supported=20transports=20via=20DNS |Sender:=20; bh=X3Y9Sq9Wlq38W54iIEPLyX34kxLuWeKp+vK2deiWGsY=; b=hAcWss+j3SVdrUo35eh1Bjcfc7YSWjh+BGUI6ao1fltUutPvJGdysv4Qnh u5zUVZT6IUH4LgkI9b7xiaILFjNcyzwU5aR8VQR8n6sM19r5U3L/XA8hJkYu fzZBEoqOW24QC/FtZLUBlXEV+UxXNkddGBIfW8V3bS01xihZThnp4=;
Authentication-Results: sj-dkim-1; header.From=dwing@cisco.com; dkim=pass ( sig from cisco.com/sjdkim1004 verified; );
Cc: tae@ietf.org
Subject: Re: [tae] New draft: announcing the supported transports via DNS
X-BeenThere: tae@ietf.org
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: Transport Architecture Evolution <tae.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/listinfo/tae>, <mailto:tae-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/tae>
List-Post: <mailto:tae@ietf.org>
List-Help: <mailto:tae-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tae>, <mailto:tae-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 18 Sep 2009 19:06:20 -0000

 

> -----Original Message-----
> From: Joe Touch [mailto:touch@ISI.EDU] 
> Sent: Friday, September 18, 2009 11:58 AM
> To: Dan Wing
> Cc: 'Michael Welzl'; tae@ietf.org
> Subject: Re: [tae] New draft: announcing the supported 
> transports via DNS
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> 
> 
> Dan Wing wrote:
> >> Dan Wing wrote:
> >>>> As you note, addresses are sometimes used for non-human 
> >>>> purposes, and
> >>>> with IPv6 they could be created on the fly - I wouldn't want 
> >>>> to have to
> >>>> wait to register them in the DNS vs exchanging them in-band.
> >>> So, when you exchange them (in whatever 
> >>> application-specific protocol 
> >>> you're using to exchange those addresses, e.g., SDP for 
> RTSP, SAP, 
> >>> and SIP) using that application-specific protocol is the 
> best place 
> >>> to indicate which transport protocol is supported on the host. 
> >> I might want to say "here, use this address, but use whatever 
> >> transport the other end wants to use for reliable object 
> >> transfer", which wouldn't have the information available to 
> >> the protocol that indicates the address.
> > 
> > I don't understand; if you have an existing protocol to send
> > an IPv4 or IPv6 address around, it can be extended to include
> > a port (as most application developers have found necessary,
> > as we can't have more than one HTTP server listening on port
> > 80 behind an in-home NAT), and it can likewise be extended to
> > say "TCP=yes, SCTP=yes, DCCP=no".
> 
> It can. Or it can be "here's an address and a port, you 
> figure out what transports are provided".

Sure.  That's easy -- probe for whatever transport you want to
try.

The draft draft-yourtchenko-tran-announce-dns-00 is trying to
optimize that case.

In any event, probes are necessary because there may be middleboxes
that block certain transport protocols.

> > You're saying such an extension is not possible / reasonable?
> 
> I'm saying it should not be strictly required.

I agree.  

And it isn't required.

> > Do you have a proposal you could share on the mailing list or
> > in an I-D?
> 
> No proposal; just trying to see if proposed solutions can 
> handle cases I consider useful.

Can you enumerate those requirements, or shall we just throw things at the
wall?  This goes back to Caitlin's post
<http://www.ietf.org/mail-archive/web/tae/current/msg00114.html> which
suggested we take a step back and look at what we want.  I'm all for doing
that.  This list has been too quiet, so we wrote a straw man.  I take it you
don't like the straw man because it's trying to cover the DNS use-case, and
your use-case is IP address literals, and your use-case can incur additional
round trip(s) to learn which transport protocols the server supports.

-d


> Joe
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.9 (MingW32)
> 
> iEYEARECAAYFAkqz2E4ACgkQE5f5cImnZrs0LQCfePjjO8Fa7GYn627BH3pxn31b
> FOEAn2/DF1X8mkmWmrYrOKd3sQVAwtGl
> =0YqU
> -----END PGP SIGNATURE-----