On 04/17/2013 02:28 PM, Marius Petrescu wrote:
When you take in account OpenVPN and the problems related to UDP in VoIp communications, take in account that there are also OpenVPN tunnels over TCP, which maintain the proper packet order and don't have the mentioned problem.
I think the problem (if there is any problem at all) *is* OpenVPN over TCP. Ordering isn't the problem: the problem is that there's no point in retransmitting a dropped packet when it represents real-time audio that's already happened. The receiving device has already moved on.
This is why RTP operates over UDP. If RTP happens to be encapsulated in a tunnel that runs over TCP, then you have violated the design assumptions of RTP. Fortunately, OpenVPN can also be configured to work over UDP.
I'm rather doubtful that a properly configured OpenVPN tunnel presents any issues with VoIP. I wouldn't believe any such claims without a properly cited reference, since I have several handsets that connect to a remote office through OpenVPN over the public internet with no issues whatsoever. Not that I've performed extensive research on the subject, but I figure my phone manufacturer did some testing before deciding to put OpenVPN connectivity in all of their handsets, and I've never had a reason to doubt their conclusion.