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

"Dan Wing" <dwing@cisco.com> Sat, 26 January 2013 05:21 UTC

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From: "Dan Wing" <dwing@cisco.com>
To: "'Hadriel Kaplan'" <HKaplan@acmepacket.com>, "'mmusic'" <mmusic@ietf.org>
References: <20130110224503.20977.89170.idtracker@ietfa.amsl.com> <157CAB7C-8AF8-4F98-9165-10A000DC9EA5@cisco.com> <021201cdef86$96f50ab0$c4df2010$@cisco.com> <A6368A20-007B-4A25-B39F-8FA1E685A7CA@acmepacket.com>
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Date: Fri, 25 Jan 2013 21:21:35 -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 Hadriel Kaplan
> Sent: Friday, January 25, 2013 12:53 PM
> To: mmusic
> Subject: Re: [MMUSIC] I-D Action: draft-ietf-mmusic-media-path-
> middleboxes-06.txt
> 
> 
> On Jan 10, 2013, at 6:02 PM, Dan Wing <dwing@cisco.com> wrote:
> 
> > 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.
> >
> 
> I don't think it can or should say "SBC" - because this doc does not
> describe what an SBC does.  At least not the first half (section 4),
> which is really about an inline ALG in the router/firewall. (ie, it's
> not the target/source of the IP addresses of the packets, doesn't change
> SIP/SDP, etc.)

Yes, you're right.  Thanks.

> Anyway, I read this latest draft, and it looks exactly like the older
> ones, so I don't see it fixing the issues with the older ones:
> 1) It claims to describe the impact on ICE, but doesn't
> 2) Doesn't describe the issues with forked or moved calls on early in-
> band media signaling (especially if you actually comply with
> recommendations #2+#4)
> 3) Uses terminology from ancient history (ie, RFC 3303) that no one else
> uses

Which is where I got confused.  I thought it was trying to describe
what is sometimes called a 'decomposed SBC', where the B2BUA is 
controlling the media relaying function using a 
protocol-similar-to-MIDCOM.

I agree nobody uses "MIDCOM" or "MIDCOM architecture" to describe
how an ALG within a firewall or an ALG within a NAT (or NAPT) 
functions.

-d


> 4) Recommendation #5 is backwards I think - it should recommend
> protocols not to require/expect to exchange media-plane signaling after
> the session has been terminated. (in other words, since you can't rely
> on middleboxes being lenient, don't design a protocol to expect them to
> be so)
> 
> -hadriel
> 
> 
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