[reSIProcate] Two UAs behind same NAT

[Alan Hawrylyshen]

On Jul 5, 2005, at 14.16, Eustanos wrote:

> Hi friends,
>
> I have UA which detected it's IP address using STUN. When I run two  
> UAs behind same NAT
> I have problem. They are unable to make a succesfull call, they  
> provide SDP with public IPs.
> They cannot connect to each other using that addresses. How this  
> kind of problem should be solved ?
>
> Thank you for your time.
> Mariusz Ciepły.

At the heart of this problem is that the NAT will not 'hairpin' the  
RTP. You are telling both UAs to send RTP to the public address of  
the NAT.
There are almost no (none?) commercial residential grade NAT devices  
that allow you to send datagrams from the NAT-ed network to the
NAT-ed network via the public interface on the NAT.

See the ICE drafts and NAT scenarios documents for more information  
about these problems.

ICE:

https://datatracker.ietf.org/public/idindex.cgi? 
command=id_detail&id=11119

NAT Scenarios:

https://datatracker.ietf.org/public/idindex.cgi? 
command=id_detail&id=9094

Hope this helps,


Alan Hawrylyshen
reSIProcate Project Administrator
http://sipfoundry.org/reSIProcate/
a l a n a t j a s o m i d o t c o m