Re: [pntaw] Real-time media over TCP

["Tirumaleswar Reddy (tireddy)" <[e-mail]>]

> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]] On Behalf Of Dan
> Wing (dwing)
> Sent: Tuesday, October 15, 2013 5:31 AM
> To: [e-mail]
> Cc: [e-mail]; [e-mail]
> Subject: Re: [pntaw] Real-time media over TCP
> 
> 
> On Oct 14, 2013, at 12:06 PM, [e-mail] wrote:
> 
> > Hi,
> >
> > In practice I doubt you find many situations where UDP is completely blocked
> but incoming TCP connections from anywhere are allowed.
> 
> Agreed.
> 
> But if both ends are trying to communicate with each other, their
> communications will appear as a TCP simultaneous-open.  That could (in fact,
> "should") work across a firewall because the firewall will see an outbound SYN
> to a host/port after which it will see an inbound SYN from that same
> host/port.

But firewall TCP inspection causes the inbound SYN from the same host/port to be dropped (Firewalls typically do not permit TCP simultaneous-open). Even with NAT as per the survey results in ICE TCP (http://tools.ietf.org/html/rfc6544#appendix-A) TCP simultaneous-open worked only in roughly 45% of the cases.

-Tiru.

> 
> -d
> 
> 
> > I'm not sure the use cases and requirements document really claims that to
> be the case, but I agree it is somewhat ambiguous. That means that while
> direct TCP connection would be better than TCP based relay, its success rate
> would be very small. I suppose we agree that UDP based relay would still be
> better than direct TCP for real-time media.
> >
> > Markus
> >
> >> -----Original Message-----
> >> From: [e-mail] [mailto:[e-mail]] On Behalf
> >> Of ext Parthasarathi R
> >> Sent: 14 October, 2013 21:55
> >> To: [e-mail]
> >> Subject: Re: [pntaw] Real-time media over TCP
> >>
> >> Hi all,
> >>
> >> My point is that the direct media connection has to be given priority over
> >> TURN based mechanism. In case of ICE-TCP, there is a possibility for the
> >> direction connection between two browsers involved in the WebRTC session
> >> and should be given priority over TURN based mechanism. So, 6) TCP based
> >> candidates (ICE-TCP) - MUST
> >>
> >> There is an assumption in the discussion that the incoming TCP traffic is
> not
> >> allowed through firewall. In case it is the problem to be solved, RTCWeb
> >> usecase and requirement has to be updated. I noticed in
> >> draft-ietf-rtcweb-use-cases-and-requirements-12 (published today) that
> >> there is no such requirement. I'll write the mail in RTCWeb WG to get the
> >> clarity on the requirement in case the firewall forbidding incoming TCP
> traffic
> >> is a matter of missing text in the requirement.
> >>
> >> Thanks
> >> Partha
> >>
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