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Ivan_Markovic_3's avatar
Ivan_Markovic_3
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Oct 25, 2012

Problems with NATing SIP traffic

Hello everyone,

 

We have VOIP Central (Splicecom) at 10.0.0.20 and SIP Trunk at 10.0.0.10. Also we have LAN at 192.168.20.0/24. Both (Splicecom and LAN) are attached to F5 interfaces.

 

We try many ways to make this working from desktop applications on LAN network but without success. Can you give me some instructions how to do this or some tips for debugging problems?

 

Thanks,

 

Ivan

 

8 Replies

  • Hey Ivan. Could you provide some more detail please? What's not working? What are the VLANs and IPs on the F5? Are you using Route Domains? What modules do you have? What Virtual Servers etc. etc.
  • Hi Ivan,

     

    As Steve said some more info. is required to help u in this matter. What I am getting from ur post is that u have a port on LTM confgured as LAN with IP segment192.168.20.0/24 and another segment as 10.0.0.x/x and u want them to communicate with each other... is this what you are looking for? have u created a default route on the LTM?

     

     

    Regards,
  • Hi,

     

     

    At this moment I remove all previous settings and now I have on one port with IP segment 192.168.20.0/24 and another one with IP segment 10.0.0.0/24. And yes I want from them to communicate.

     

     

    I have default route defined as:

     

    destination 0.0.0.0

     

    netmask 0.0.0.0

     

    gateway (ours internet link public ip from isp)

     

     

    Can you give me some further instructions?

     

     

    Thanks,

     

    Ivan

     

  • If you're looking to route between subnets without the traffic being handled by LTM you'll need to configure some routing Virtual Servers. Details here: http://support.f5.com/kb/en-us/solutions/public/7000/500/sol7595.html?sr=24070250
  • Hello,

     

     

    I have some progress now and calling is working. I can call any phone number from my desktop application and make connection. But now I don't have voice? I assume that some packets are not forwarded well? Can you give me some intrustions?

     

     

    The configuration now:

     

     

    - All interfaces are in the same VLAN.

     

    - I have SelfIP with 10.0.0.19 address.

     

    - One NAT from 192.168.20.0/24 to 10.0.0.0/24

     

    - One NAT from 10.0.0.0/24 to 192.168.20.0/24

     

     

    Thanks,

     

    Ivan
  • Can you clarify, have you configured two static NATs or used an SNAT?

     

     

    Also, it might be necessary to enable SNAT Packet Forwarding for All Traffic: System > Configuration > Local Traffic > General.

     

     

    Are you able to do a tcpdump on the device and take a closer look at what's happening?
  • Hi Steve,

     

     

    I have two static NATs, and SNAT Packet Forwarding for All Traffic is enabled. I'm trying now to set up enviroment.

     

     

    Thanks,

     

    Ivan
  • OK, so I'm not sure you need both NATs, just the one should work both ways I would have thought.

     

     

    Why are you NATting at all?

     

     

    Again, it would be very useful if you could do a tcpdump if possible.