[SR-Users] Kamailio to Asterisk Proxy with NAT

[Daniel Tryba]

On Thu, Mar 29, 2018 at 11:37:37AM +0200, Benjamin Marty wrote:
> I need the scenario for scalability on the asterisk side.
> 
> The scenario I still have in my head is that the clients -could- do the RTP
> stream directly with the Asterisk Server. The Asterisk Instances have all
> their own NATed Public IP (AWS EC2 Instances). But I think I will build
> more problems than solving complexity with that approach.
> 
> I quite like the approach to use the internal network and don't use the
> Asterisk Public IP's at all. So basically all Clients are doing SIP
> Signalling + RTP Mediastream over the Kamailio Instance. Or would you avoid
> that?

I'd go for direct RTP from client to asterisk. The proxy is a single
point of failure. Not running rtpengine/proxy makes the loadbalancer
easier and kamailio could be stateless. Since the asterisk machines have
a unique public ip, all you need to do is advertise this address
(media_address in chan_sip, no idea what it is in pjsip). Also this is
cheaper if EC2 costs are based on cpu time spend on you proxy instance.