Re: [MMUSIC] I-D Action: draft-ietf-mmusic-media-path-middleboxes-06.txt

"Dan Wing" <dwing@cisco.com> Thu, 10 January 2013 23:02 UTC

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From: "Dan Wing" <dwing@cisco.com>
To: "'Gonzalo Salgueiro'" <gsalguei@cisco.com>, "'mmusic'" <mmusic@ietf.org>
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Date: Thu, 10 Jan 2013 15:02:37 -0800
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Subject: Re: [MMUSIC] I-D Action: draft-ietf-mmusic-media-path-middleboxes-06.txt
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> -----Original Message-----
> From: mmusic-bounces@ietf.org [mailto:mmusic-bounces@ietf.org] On Behalf
> Of Gonzalo Salgueiro
> Sent: Thursday, January 10, 2013 2:47 PM
> To: mmusic
> Cc: obsidian97@gmail.com
> Subject: Re: [MMUSIC] I-D Action: draft-ietf-mmusic-media-path-
> middleboxes-06.txt
> 
> MMUSIC -
> 
> I have simply updated the version of this draft to prevent expiration
> because recent discussions with the chairs have confirmed that we are
> ready now to progress this milestone. As part of that effort the chairs
> requested we clearly define the purpose, scope, and intended audience
> for the document.
> 
> I came a bit late to the party but from my perspective this draft's
> purpose is to provide guidance and best practices on mitigating the
> issues middleboxes (particularly NATs and firewalls) can cause to end-
> to-end SIP/SDP-signaled media streams in different architectures.  The
> target audience is anyone (i.e. NAT/FW vendors, protocol designers,
> etc.) wanting such information ond that might benefit from the design
> tips to make their network/protocol/device more middlebox friendly.
> 
> I believe Flemming's recent comments (as an individual) masterfully
> summarized the scope, purpose and target audience for this document.
> Thus, I don't want to repeat (less eloquently) what I consider to be the
> right approach to this document.  For your convenience, here are those
> comments:
> 
> =====
> 
> A lot of the SIP and SDP work started out with a somewhat "purist"
> Internet view of the world, where things such as middleboxes were not
> considered. As other standards and industry organizations became
> interested in using SIP and SDP, different architectures were defined
> and some of those arcitectures did include the notion of middleboxes
> (e.g. 3GPP IMS and CableLabs PacketCable). From an IETF point of view,
> there was, at least initially, not a great deal of knowledge about these
> architectures and what the middleboxes defined by them were doing.
> Conversely, there was (is) also a concern that such middleboxes may
> break end-to-end transparency and hence there was a desire to try and
> alleviate that.
> 
> To that effect, it was seen as useful to have a document that could
> a) Explain what/how middleboxes might be operating in these
> architectures
> b) Provide guidelines as to how such middleboxes could minimize (ideally
> avoid) impacting end-to-end transparency and/or how protocols could be
> used to try and alleviate any impact such middleboxes might have.
> 
> The middleboxes draft is trying to address the above as it relates to
> the media path. The target audience is thus IETF participants that would
> like an overview of how these middleboxes may affect SIP/SDP-signaled
> media streams as well as what can be done to try and overcome that.
> Similarly, the document is targeted at people involved in these "other"
> architecture efforts, with a goal of making it clear how middleboxes may
> affect the operation of SIP/SDP-signaled media streams and hence provide
> some "design principles". This is not unlike some of the NAT work that
> was done in BEHAVE.
> 
> It could be argued that these architectures have now been around for so
> long that producing the above document will not make any difference at
> this point. While I have some sympathy for this, I also think we have to
> recognize the importance of documenting what we know and to make that
> readily available for new people that will be working in this space.
> 
> In other words, I still believe there is value in pursuing this
> document. As to whether it should be a BCP or Informational, I don't
> have any strong opinions.
> 
> =====
> 
> As a group can we agree on this scope and that is worthwhile to finally
> complete this milestone?  Feedback welcome.

I am glad this document was resurrected.  

Can the document say SBC instead of the awkward (and inaccurate) 
"SIP ALG combined with MIDCOM agent"?  Or is saying SBC impolitic.

-d


> Cheers,
> 
> Gonzalo
> 
> 
> On Jan 10, 2013, at 5:45 PM, Internet-Drafts@ietf.org wrote:
> 
> >
> > A New Internet-Draft is available from the on-line Internet-Drafts
> directories.
> > This draft is a work item of the Multiparty Multimedia Session Control
> Working Group of the IETF.
> >
> > 	Title           : Analysis of Middlebox Interactions for Signaling
> Protocol Communication along the Media Path
> > 	Author(s)       : Brian Stucker
> >                          Hannes Tschofenig
> >                          Gonzalo Salgueiro
> > 	Filename        : draft-ietf-mmusic-media-path-middleboxes-06.txt
> > 	Pages           : 22
> > 	Date            : 2013-01-10
> >
> > Abstract:
> >   Middleboxes are defined as any intermediary box performing functions
> >   apart from normal, standard functions of an IP router on the data
> >   path between a source host and destination host.  Two such functions
> >   are network address translation and firewalling.
> >
> >   When Application Layer Gateways, such as SIP entities, interact with
> >   NATs and firewalls, as described in the MIDCOM architecture, then
> >   problems may occur in the transport of media traffic when signaling
> >   protocol interaction takes place along the media path, as it is the
> >   case for recent key exchange proposals (such as DTLS-SRTP).  This
> >   document highlights problems that may arise.  Unfortunately, it is
> >   difficult for the end points to detect or predict problematic
> >   behavior and to determine whether the media path is reliably
> >   available for packet exchange.
> >
> >   This document aims to summarize the various sources and effects of
> >   NAT and firewall control, the reasons that they exist, and possible
> >   means of improving their behavior to allow protocols that rely upon
> >   signaling along the media path to operate effectively.
> >
> >
> > The IETF datatracker status page for this draft is:
> > https://datatracker.ietf.org/doc/draft-ietf-mmusic-media-path-middlebo
> > xes
> >
> > There's also a htmlized version available at:
> > http://tools.ietf.org/html/draft-ietf-mmusic-media-path-middleboxes-06
> >
> > A diff from the previous version is available at:
> > http://www.ietf.org/rfcdiff?url2=draft-ietf-mmusic-media-path-middlebo
> > xes-06
> >
> >
> > Internet-Drafts are also available by anonymous FTP at:
> > ftp://ftp.ietf.org/internet-drafts/
> >
> > _______________________________________________
> > I-D-Announce mailing list
> > I-D-Announce@ietf.org
> > https://www.ietf.org/mailman/listinfo/i-d-announce
> > Internet-Draft directories: http://www.ietf.org/shadow.html or
> > ftp://ftp.ietf.org/ietf/1shadow-sites.txt
> >
> 
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