Re: draft-rosenberg-midcom-turn-06: Why a client has to send data first before receiving any UDP data?

If Phone1 won't first send data out to Phone 2 using the TURN Send
Request via Phone1's binding,  then TURN server doesn't have
default IP address and port of  Phone1's binding, so TURN server
couldn't  know where it sends the non-TURN packets received from 
Phone1 on Phone1's binding.

Forthermore, If  Phone1 can receive data not using TURN Send Request, 
Phone1 can receive any data from any node, because it is equivalent to 
ignoring "permission" flag added when TURN Send Request is got through.

> Hi all,
> 
> In the new TURN draft, it mentions that the client has to send data 
> first (using TURN Send Request) before receiving any UDP data (Section 8.6).
> 
> I am using the TURN for two VoIP phones. I assume each of them will do a 
> TURN allocation to request their own binding. Phone 1 will send RTP to 
> Phone 2 via Phone 2's TURN binding, while Phone 2 will send RTP to Phone 
> 1 via Phone 1's TURN binding.
> 
> However, the specification mentions that Phone 1 will first send data 
> out to Phone 2 using the TURN Send Request via Phone 1's binding. I am 
> confused here, as I have no idea why I need to do this. Also, what data 
> should I be sending? Any idea?
> 
> I am also using ICE with TURN.
> 
> Thanks.
> 
> Best Regards,
> Tony Cheung
> 
> 
> 
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