Running VoIP over SSL VPNs? (Network World article)

[Volker Tanger <vtlists (at) wyae.de>]

Good morning!

On Tue, 21 Feb 2006 23:22:26 -0500
Lee Dilkie <lee_dilkie (at) mitel.com> wrote:
>   
> I  could run VoIP over SMTP if I cared to deal with the latency and
> jitter  but it's hardly a reasonable thing to do. Of all the VPN
> technologies,  IPsec is the only one that makes sense. And even IPsec
> is deemed a  suboptimal fit for RTP due to bandwidth considerations.
[...]
> Running RTP over tcp (SSL or not) is just not practical in a real 
> network (ie. internet) as it's not the latency but the jitter
> introduced  by re-transmission that'd kill you. 

IPSec and SSLish UDP (OpenVPN, to name the beast) are more or less equal
with respect to delay and CPU ressources. OpenVPN has a bit more
overhead packet-size-wise of course, but is much easier to handle
with NAT devices (of course).

The main reason to use a standard VPN usually is that the hardphones
used simply don't do SRTP or similar...
;-)


> Voice can  tolerate reasonable loss a lot better than it
> can handle network jitter.  

...especially with a loss-tolerant codec like iLBC or alike.

Bye

Volker


-- 

Volker Tanger    http://www.wyae.de/volker.tanger/
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