Re: TURN

Toshihiro Sonoda wrote:

> I have two questions about turn.
>
> Q.1
> Assuming the following topology.
>
>
> 　　+---------+
> |TURNserver|
> 　　+---------+
> |
> |
> 　　+--------+ +--------+
> |symmetric1| |symmetric2|
> 　　+--------+ +--------+
> | |
> | |
> 　　+-------+ +--------+
> | client1 | | client2 |
> 　　+-------+ +--------+
>
> Client1 and clients wants to connect each other. Client1 knows TURN 
> server, and it is behind symmetric 1.
> But client2 doesn't know TURN server, and it is behind symmetric2.
> Client1 and client2 can exchange data channel information using 
> signaling channel, like SDP of SIP.
>
> Then, can client1 and client2 be connected?

Assuming the data transport is RTP, which is a uni-directional data 
transport, only client2-to-client1 data channel might be able to be 
established.
Otherwise, a bi-directional data channel might be able to be 
established, depending on the transport protocol used.

>
> If turn server emulates Restricted NAT, but not Port Restricted NAT,
> then I think client 1 and client2 can be connected.
> Are there any problem if turn server emulated Restricted NAT.

A TURN server is a application layer media relay, but not a NAT emulator.
If a TURN server relays packets in a similar manner as a restricted NAT 
routes packets, you would not be able to differentiate which packets are 
from which transport address.

>
>
> Q.2
> Assuming the following topology.
>
>
> 　　+----------+ 　　+----------+
> |TURNserver1| |TURNserver2|
> 　　+----------+ 　　+----------+
> | |
> | |
> 　　+--------+ +--------+
> |symmetric1| |symmetric2|
> 　　+--------+ +--------+
> | |
> | |
> 　　+-------+ +--------+
> | client1 | | client2 |
> 　　+-------+ +--------+
>
> Client1 and clients wants to connect each other. Client1 knows TURN 
> server, and it is behind symmetric1.
> Client2 knows TURN server, and it is behind symmetric2.
> Client1 and client2 can exchange data channel information using 
> signaling channel, like SDP of SIP.
>
> Then, I think client1 and client2 can be connected, using double 
> relaying.
> This is, clietn1 <-> TURNserver1 <-> TURNserver2 <-> client2.
> But, this is not efficient. Do you have good idea for connecting peers 
> under
> above situation?

Yes, they could be connected (two uni-directional data paths).
If they were both authorized for use of the same TURN server, they could 
do that for the sake of efficiency, latency and etc.
There are probably better solution for this scenaio, I would like to 
know, too.

>
> Thank you for advices.

Hope my response would be helpful : ).

>
>
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