[OpenSIPS-Users] load balancing behing a NAT

[Madhu]

Hello,

I am trying to use opensips as a loadbalancer for some asterisk Servers that offer the
same exact configuration. (using the load_balancer modul).

The problem ist that my instalation is NATed and there is little i can do about that. 

setup:
1) opensips registers with external ip at a sip provider (xxx.yyy.zzz.aaa)
2) the 5060 port is forwarded to opensips[192.168.1.20]
3) the media port ranges are forwarded to the asterisk servers (e.g. 6000-6999UDP-> asterisk01[192.168.1.31] , 7000-7999UDP-> asterisk02[192.168.1.32], ...)
4) if a call arrives it is sent to opensips, which in turn forwards this call to the asterisk
-- this far it works
5) the sip handshake works till the first ACK from the sip provider is received, which is not forwarded to the asterisk machine.

Q1: how to make opensips forward the ACK and all following packages.
Q2: from what i have seen so far the nat_traversal module is designed for
       clients only. and can not directly be used for a server. is this correct?
Q3: if possible, how can nat_traversal be used in this setup?
Q4: In which Database are the current open calls stored?
       I a way to get the current load  to trigger outgoing calls from the asterisk with the least load.

find attached the (anonymized) config + sip call trace from Wireshark

best regards.
Madhu


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