Subject: RE: [midcom] Moving SPAN along

From: "Cullen Jennings" <[email-masked]>
Date: Sun, 1 Sep 2002 07:38:17 -0700

This falls into your category of both ends cooperate via a standardized
mechanism but here is one possible idea.

The two endpoint set up a communication channel that is guaranteed to work
via TURN. Then endpoint A send a token and it's private address to endpoint
B over this channel.  Endpoint B looks at the private address and tries to
directly send the token to A's private address. If A receives the correct
token, they know they can talk to each other.

Cullen

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Francois Audet
Sent: Thursday, August 29, 2002 5:11 PM
To: 'Jonathan Rosenberg'; Sanjoy Sen
Cc: 'Melinda Shore'; 'Pete Cordell'; [email-masked]'
Subject: RE: [midcom] Moving SPAN along

> The problem is not the case when two clients are behind the same NAT.
> There are many ways to detect this, and once you know it, you can use
> your private addresses.

Can you expand on the "many ways" to detect this?
I can't think of any way that does not require that both end cooperate on
this
through some standardized mechanism.

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---

From: "Cullen Jennings" <[email-masked]>
Date: Sun, 1 Sep 2002 07:57:43 -0700

I think there are two orthogonal questions.

The first question is UDP traversal in cases where STUN will not work. I
think this is a questions worth solving.

The second question is TCP traversal. I wish we could solve this but I'm not
sure it is possible without running into the issue of violating the policy
that the firewall administrator is trying to provide. If people think we can
do a generic solution for peer to peer TCP - I'm very interested in figuring
out how. If people don't think we can then, unfortunately, I think we may be
stuck with doing traversal of TCP with application specific relays. H.323
and IM are some good use cases to think about - though 323 may just use
Annex E to avoid this and SIMPLE may use sip like proxies as application
level relays. I'd like to solve this problem but before we can figure out if
a solution is possible, we need to figure out what our constraints are from
the point of view of firewall policy.

Cullen

> Melinda Shore
> Sent: Wednesday, August 28, 2002 7:54 AM
> To: Pete Cordell
> Cc: [email-masked]
> Subject: Re: [midcom] Moving SPAN along
>
>
> At this point there seems to be very little support for
> continuing to work on SPAN.  The question is whether or not
> the problem of traversing symmetric NATs is sufficiently
> compelling.  If it is we need to continue; if not we can
> consider dropping the deliverable.  Let's try to resolve
> this question over the next few days.
>
> Melinda