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: mico...@gmail.com >> To: sr-users@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 >> _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
