I have a VoIP application that I'm trying to run over the PPTP VPN tunnel on a RV120W router.
The system is a NEC SV8100 PBX communicating with the NEC soft phone (SP310). The system uses SIP to set up the call and for other signaling information. It uses RTP to transmit/receive the audio stream.
The problem I'm having is that there is no audio stream from the soft phone. The SIP communication and the audio stream to the soft phone works fine. The symptom is: from the soft phone, the remote party cannot hear you, but you can hear them.
I did a packet trace on the RV120W and found the following:
PT=ITU-T G.711 PCMU, SSRC=0x7F1621CA, Seq=14361, Time=779040
PT=ITU-T G.711 PCMU, SSRC=0xE943F2E7, Seq=19090, Time=3940936556
192.168.1.252 => NEC PBX
192.168.1.52 => Soft phone connected via PPTP
192.168.1.1 => RV120W
As you can see, the Source IP address is being changed from its original 192.168.1.52 to 192.168.1.1. The NEC PBX is expecting the packet to be coming from the softphone, (192.168.1.52) not the RV120W (192.168.1.1). As a result it ignores the RTP packet from the soft phone and does not relay it to the remote party.
Is there any reason why the RV120W is performing NAT on PPTP packets? Can this be disabled somehow?
Any ideas will be helpful.
Solved! Go to Solution.
It looks like there was a similar issue on the RV220W that was fixed in firmware v184.108.40.206 of that model:
Fixed an issue in which enabling a PPTP server changed the port
forwarding Source IP Address to the LAN IP address of the router instead of
the IP address of the device that was used to access the service.
This is exactly the problem that I'm having with the RV120W. Is this a known problem that will be fixed in the next firmware release? Does anyone know the ETA for the next release of RV120W firmware?
I don't see any open Cdets/bugs regarding the issue specified. I would call the SBSC @ 1-866-606-1866 and open a support case so we can start documenting your issue and verifying if this could possibly be a bug with the RV120.We would need some packet captures, syslogs, and any other trouble shooting steps you have completely. Once we have good documented case with replication of your issue and verified all this information we can get approval for escalation.
Thanks for the information! I've contacted your SBSC office and have started a case regarding this problem. I will assemble as much data on the issue as I can and email it to your office.
Just for you reference, Cisco has assigned a case ID to this trouble. If you need the specific case number, let me know.
Hi. I have the same issue with this router.
After enabling PPTP Server forwarded requests from Internet to internal services have internal IP address of the router as the source address.
Because of that doesn't work spam-filter on internal mail server for example.
Should I open a new case with Support team as Joe did?
I have latest firmware at the moment - 220.127.116.11
I doubt you need to open a new support case for this... my existing case (#620173783) is registered with Cisco and I've been in contact with several of their support engineers. According to them, the problems with enabling the PPTP server on the RV120W router is a known bug. They were able to reproduce the problem that I had outlined in my initial post and are (hopefully) working to solve the problem.
None of the people I've been in touch with have been able to provide an ETA for a fix. If you want, you can get a refund for your defective router from Cisco. I ended up using a RV220W for my particular application... the PPTP server on that router does not cause these extraneous NAT problems.
Best of luck to you!
having a similar issue like you, but with CiscoRV180 and with Avaya IP Office IP-PBX and Avaya softphone, How did you solve your problem, are you using cisco RV220W? or not, are your voip services working fine over PPTP?
Thanks for your help
Yes, I am using the RV220W for that particular application. VoIP services work normally over the PPTP tunnel on the RV220W.
It is disappointing that Cisco has not resolved the problem with the RV120W... seems like a very trivial fix to me.
There is a beta firmware 1.0.3.x that fixed the issue you mentioned. You would have to call the support center to get the beta firmware through an escalation process.
Message was edited by: tekliu
It turned out that firmware 18.104.22.168 has not fixed the issue. So we will have to wait for the next firmware. Sorry for the false optimism.
I don't see this firmware version listed on the RV120W's firmware download page:
Are there other bugs that have been fixed in this release? Has the release been delayed until the PPTP server issue is resolved?