[OpenSIPS-Users] Load balancer behind NAT

Muhammad Shahzad Shafi shahzad at voip-demos.com
Thu Aug 1 06:57:25 CEST 2013

I think your opensips would have two interfaces, one for public ip, 
from where the client request comes in and one on private ip to send 
call to FS.

Now, since call is come to FS from local LAN (private ip of opensips), 
therefore, it will most likely won't any NAT adjustments for it, 
resulting in media flow failure. So,

1. Is this assumption correct or your architecture is more complex then 
2. How does FS connects to internet, does you have different gateway to 
internet for FS compare to opensips?

If any or both question is yes, then you can either,

1. Try using ext-rtp-ip parameter in sofia profile,


2. You can also change rtp ip in sdp on opensips using fix_nated_sdp 

3. If your internet gateway is running fairly recent version of linux 
kernel >= 3.x then loading sip nat kernel module will also do the trick, 
(but its not guaranteed to work in all distros, i can only confirm it in 
ubuntu 12.x+ and debian 7.x+).

modprobe -r ip_nat_sip
modprobe -r ip_conntrack_sip

4. Install rtpproxy and enable it in opensips in bridged mode.

For solution 1 - 3, port forwarding must be enabled on your FS's 
internet gateway.

Thank you.

On 2013-08-01 03:49, Jose Suero wrote:
> Some aditional info,
> I'm trying not to use RTPProxy for this, so I can have the load on
> freeswitch servers as opposed to have all calls (RTP) on the opensips
> server.
> Any help would really be appreciated, i've searched all day with no 
> luck
> thanks in advance
> On 2013-07-31 13:52, Jose Suero wrote:
>> Hello all
>> I'm trying to setup opensips as proxy/loadbalancer for freeswitch,
>> following
>> http://wiki.freeswitch.org/wiki/Enterprise_deployment_OpenSIPS
>> right now I'm able to register to opensips which sends the
>> registration to freeswitch, and when I dial a number it goes to
>> freeswitch and gets dialed, the problem is that the phone tries to
>> connect to freeswitch server's internal IP.
>> If I connect to freeswitch directly everything works fine, 
>> freeswitch
>> advertises correct NAT address, but not thru opensips
>> I'm using dispatcher for registration and LoadBalancer with this 
>> script
>>        if (is_method("INVITE")) {
>>                 if (!load_balance("1","pstn","1")) {
>>                         send_reply("503","Service Unavailable");
>>                         exit;
>>                 }
>>         }
>>         else if (is_method("REGISTER")) {
>>                 if (!ds_select_dst("1", "0")) {
>>                         send_reply("503","Service Unavailable");
>>                         exit;
>>                 }
>>         }
>> thanks in advance
>> Jose Suero
>> _______________________________________________
>> Users mailing list
>> Users at lists.opensips.org
>> http://lists.opensips.org/cgi-bin/mailman/listinfo/users
> _______________________________________________
> Users mailing list
> Users at lists.opensips.org
> http://lists.opensips.org/cgi-bin/mailman/listinfo/users

Mit freundlichen Grüßen
Muhammad Shahzad
CISCO Rich Media Communication Specialist (CRMCS)
CISCO Certified Network Associate (CCNA)
Cell: +49 176 99 83 10 85
MSN: shari_786pk at hotmail.com
Email: shaheryarkh at googlemail.com

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