[SR-Users] Looking for RTP Proxy in TCP

[Daniel-Constantin Mierla]

On 6/8/12 1:26 PM, Aft nix wrote:
> On Fri, Jun 8, 2012 at 2:18 PM, Andrew Pogrebennyk
> <apogrebennyk at sipwise.com> wrote:
>> 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
>>>>
>> _______________________________________________
>> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
>> sr-users at lists.sip-router.org
>> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
>
> These things are wild attempt to escape some telcos blocking UDP
> packets suspecting VOIP for pushing their own IP telephony product.
> Sometimes even encrypted media is blocked because their DPI use some
> heuristic methods for detecting media packet. Like payload size in
> different codecs can give a clue about the packet. Although This bites
> in the a** of whole "net neutrality" campaign, They don't bother.
>
> These practices force VOIP providers for "obsfucation" techniques for
> escaping the DPI. Interesting thing is i know of some situation when
> they blocked VPN because people were using it to make VOIP calls. Now
> you can use VPN for other purposes!
>
> Some telco even went to lengths to block UDP "streams" by calculating
> some "threshold" bandwidth consumption.
>
> The DPI vendors are making a business case, but it all comes at price
> of making Provider inventing non standard schemes to do ordinary
> stuffs.
>
> Media over TCP is the worst idea in the history of worst ideas. But
> sometimes you have no choice.
>
> I guess big web companies should push these telcos who are afraid of
> losing their traditional TDM market share and going at lengths to stop
> media over IP.
look at htproxy:

http://www.mbdsys.com/foss/htproxy/file/f16c43f3c3c3/README

it is kind of http proxy that can be used to tunnel udp packets. You 
need to have a client application supporting it, on the sip server side 
you don't need anything.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 - http://asipto.com/u/katu
Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 - http://asipto.com/u/kpw