Subject: Re: [Simple] A new draft on using ICE with MSRP

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 01 Mar 2007 23:05:55 -0500

I read this with much interest. I've thought about this too, on and off, 
as ICE matured and gained new functionality. TCP, and then TLS got 
added, and the ability to have two TURN relays for a trapezoid 
configuration.

I think the main thing that needs to be pointed out here is that, with 
ICE, you will end up with a separate TCP connection between a particular 
relay pair, for each session. One of the initial goals of MRSP relays 
was to allow connection reuse between peer networks. This has pros and 
cons; the scalability goes down, but now you can do cool stuff like e2e 
TLS, and if you combine that with self-signed certs and exchange of 
fingerprints you get a nice solution for e2e media encryption. 
Unfortunately I have no doubt that many folks won't want that because of 
the need to enforce policies on who can say what to whom, but at least 
the capability is there.

On your open issue regarding framing, I see no problem with using the 
framing in RFC4571 with MSRP. I chose it because it will work with 
ANYTHING.

I think it'd be great to work on this further and fully flesh out the 
pros/cons, backwards compatibility considerations and so on.

-Jonathan R.

Aki Niemi wrote:

> Hi all,
> 
> I've submitted a straw man proposal for using Interactive Connectivity
> Establishment (ICE) with MSRP. The idea is to have the ability to use
> the same NAT-traversal infrastructure with MSRP as with other media
> sessions. Until it appears at the I-D directories, copies can be fetched
> here:
> 
> http://people.nokia.net/~aki/drafts/draft-niemi-simple-msrp-ice-00.txt
> http://people.nokia.net/~aki/drafts/draft-niemi-simple-msrp-ice-00.html
> 
> Comments are most welcome. The draft is a little rough around the edges,
>  apologies for that.
> 
> Cheers,
> Aki
> 
> 
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> 

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Cisco Fellow                                   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
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---

From: Aki Niemi <[email-masked]>
Date: Tue, 06 Mar 2007 13:59:43 +0200

Hi Jonathan,

ext Jonathan Rosenberg wrote:
<snip />
> relay pair, for each session. 

Yes, this is perhaps the biggest issue that needs to be clearly spelled
out. The ripple effect of it is that you could now drop the To-Path and
From-Path from MSRP SENDs, since ICE does connection validation, and
strictly e2e streams don't need this embedded routing information either.

I understand these may be going too far into redesigning the entire
protocol, but certainly topics worth discussing.

> One of the initial goals of MRSP relays

Very true.

> the need to enforce policies on who can say what to whom, but at least

Right. I also tend to think that some form of logging and/or limited
policy enforcement will be possible (i.e., you can cat the stream into a
file and store it at the TURN relay), but emphasizing the work "limited"
here.

> framing in RFC4571 with MSRP. I chose it because it will work with

Correct, it will work, but will also not be strictly needed. My point
was that since MSRP does framing just fine, you can already mux MSRP and
STUN, right?

For other protocols, such as RTP/RTCP or, say, DNS-over-UDP (wha?),
RFC4571 is certainly required.

> pros/cons, backwards compatibility considerations and so on.

Excellent.

Cheers,
Aki