[asterisk-users] New thread - SIP over VPN

[Hans Witvliet]

On Sat, 2009-09-26 at 22:09 +0000, Jeff LaCoursiere wrote:
> On Sat, 26 Sep 2009, John A. Sullivan III wrote:
> 
> <snip>
> 
> > We are using SIP over both IPSec and SSL VPNs very successfully with
> > access controls in the tunnel ingress via the ISCS network security
> > management project (http://iscs.sourceforge.net).  There are a couple of
> > issues.
> >
> > I'm not sure what you mean by a TCP tunnel unless you are referring to
> > something like using OpenVPN over TCP rather than the default UDP.
> 
> Isn't an SSL based tunnel all TCP?
> 
No, could be either.

> [snip]
> 
> > to UDP port 1194 but can use any UDP or TCP socket.  There has been some
> > discussion that using it over TCP for VoIP can produce better results
> > because the packets are less likely to be delivered out of order
> > although perhaps with greater latency.
> 
> The resends would have to happen within the jitter buffer period, as 
> someone else pointed out, or I would think large chunks would be missing 
> in the audio (the missing packet plus all the ones queued up after it that 
> missed the jitter window).  Total speculation on my part.

Re-sending audio packets is waste of resource,
Better to have an audio-stream with an occasional missing packet, than
the delay of waiting for re-transmission and re-ordering.