>>2. Just for double confirmation is it normal that the port "from
which" I send my
>>RTP is irrelevant

It is not normal.
It is not totally irrelevant.
For NAT traversal "symmetric RTP" is important.
See section 4 of tfc 4961: http://tools.ietf.org/rfc/rfc4961.txt

Also some equipment may require that any received RTP has the same
source port
as the destination port for sent RTP.  It's a sort of integrity check.


>>port 5060 is already open and when I give this port number (source
port)
>>from which I send my RTP works perfectly fine.

It might work but it is not at all scaleable.

Regards

Attila


 

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
Siga
Sent: 08 March 2011 09:28
To: Worley, Dale R (Dale)
Cc: [email protected]
Subject: Re: [Sip-implementors] Audio Port problem

Hi Dale,
thank you for the valuable info, I am sorry with my terminology that I
made the mistake in explaining.

1. As of now I can say that the port named in the SDP that I receive is
the port "to which" I send my RTP (this is no problem and works
perfectly fine when i use this as destination port to send my RTP).

2. Just for double confirmation is it normal that the port "from which"
I send my RTP is irrelevant (then I really don't need to worry), because
as far as I can understand the port 5060 is already open and when I give
this port number (source port) from which I send my RTP works perfectly
fine.

if you say this is absolutely fine then I really don't need to worry.
The only thing I need to take care is that I should use my own defined
RTP port (which I have sent with my INVITE/SDP) to listen to incoming
RTP packets.

Correct me if I am wrong

Regards



On Mon, Mar 7, 2011 at 7:00 PM, Worley, Dale R (Dale)
<[email protected]>wrote:

> ________________________________________
> From: [email protected] [ 
> [email protected]] On Behalf Of Siga [ 
> [email protected]]
>
> I am parsing the audio port number which I get as SDP from my SIP 
> Server. I use this port number for sending my RTP Packets.
> _______________________________________________
>
> You need to be careful with your terminology.  The port named in the 
> SDP that you receive is the port *to which* you must send your RTP.  
> The port (on your system) *from which* you send RTP is irrelevant.  
> Now, you may understand this, but what you wrote does not make that 
> clear.  Similarly, the port named in the SDP that you send is the port

> on your system on which you will listen for RTP.
>
> Dale
>
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