Stopping STUN binding requests for natted PSTN voice calls RRS feed

  • Question

  • Hi,


    Does anyone know how to prevent STUN logic from triggering on OCS2007 RTM1?


    The OCS is configured as a remote SIP Gateway to a centralised Call Server. The 2 components are in seperate networks. The Call Server is non-natted, the OCS behind a symettric NAT. No firewall traversal is involved and all call set-up signalling is fine. The Call Server handles all media proxy interaction. Even if NAT traversal is required this should not be handled by the OCS components.


    The next hop on the Mediation server PSTN-GW is a Call Server public address. When a call is offered to the OC client the SDP payload instructs the Mediation Server to send media to a proxy address which is clearly beyond NAT. This scenario triggers a STUN binding request from the client to the mediation server. This request is sent via the Media NAT to the Media Proxy and the unexpected message disrupts the logic on the device, messing up the existing media binds, leading to a non-routable RTP stream. Placing an SBC with a private address in the same subnet as the PSTN-GW interface on the Mediation Server seems to stop this, as OCS does not see the call as natted, but this is not an option here.


    I'd like to prevent this STUN request from arriving at the Media Proxy, but do not want to try to filter it in the network. I've tried disabling ICE support at the client but the message still appears. Is anyone aware of any WMI or other settings that might stop the STUN request?





    Saturday, October 13, 2007 11:26 AM