18 Apr
2013
18 Apr
'13
1:51 a.m.
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.