[SR-Users] Looking for RTP Proxy in TCP

[Andrew Pogrebennyk]

The papers talk about transport protocol for signaling, not media/RTP.
I didn't hear of anyone who does RTP over TCP neither. I doubt even that
the performance is a primary reason behind that, for media over TCP the
client link must be virtually packet-loss free (due to TCP
retransmissions), while over UDP sometimes up to 5% packet loss can be
tolerated. TCP was not designed as transport for real-time media :-)

On 06/08/2012 12:35 AM, Yang Hong wrote:
> Hello.
>  
> SIP over TCP would reduce server performance significantly when compared
> with SIP Over UDP.
>  
> Please read the following two papers. Combining RTP proxy with SIP over
> TCP would degrade SIP server performance even worse.
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------
> http://www.cs.columbia.edu/~hgs/papers/Shen1008_TLS.pdf
>  
> The Impact of TLS on SIP Server Performance
>  
> "Securing SIP is accomplished by using TLS instead of UDP as the
> transport protocol. We show that using TLS can reduce performance by up
> to a factor of 17 compared to the typical case of SIP-over-UDP."
> 
> "Network operators considering deploying SIP over TLS will need to
> consider the extra resources required to provide the same service
> quality as would be the case with UDP."
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------
> http://www.cs.columbia.edu/~hgs/nossdav/2007/files/file-27-session5-paper1-nahum.pdf
>  
> Evaluating SIP Proxy Server Performance
>  
> "The next most signicant performance feature is which transport
> protocol is used, TCP or UDP. Using TCP can reduce performance anywhere
> from 43 percent (the stateful proxying scenario with authentication) to
> 65 percent (state-less proxying without authentication).
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------
> 
> Best regards,
>  
> Yang
>> Date: Thu, 7 Jun 2012 13:36:39 +0200
>> From: miconda at gmail.com
>> To: sr-users at lists.sip-router.org
>> Subject: Re: [SR-Users] Looking for RTP Proxy in TCP
>>
>> Hello,
>>
>> On 6/4/12 7:14 PM, Austin Einter wrote:
>> > Hi All
>> > Now I am using Kamailio 3.1.5 and RTP proxy 1.1.
>> > Looks both are compatible and working fine.
>> >
>> > The RTP Proxy basically sends/receives RTP packets over UDP.
>> > Is there any RTP Proxy available that does send/receive of RTP packets
>> > over TCP and also should be compatible with Kamailio 3.1.5.
>> >
>> > If you have any information in this regard, kindly share.
>> RTP itself is specified over UDP, also I am not aware of any SIP phone
>> doing RTP over TCP.
>>
>> MSRP is a mechanism specified for sending message streams over TCP, we
>> have a module for that, but I guess is not exactly what you are
> looking for:
>>
>> http://kamailio.org/docs/modules/devel/modules/msrp.html
>>
>> Maybe based on it you can implement one that fits your needs.
>>
>> Cheers,
>> Daniel
>>