Cisco Support Community
Community Member

Trouble with modem connection on CES circuit


I have mad a connection between a pabx and a 7204 VXR router (c7200-js-mz.122-13.bin). I have configurred a pvc for unstructured service and connected the cbr port with an atm port.

I can dial and fax to the other site but I can't use a modem correctly.

With a modem, a connection is made but transferring data is going really slow. If I dial in to the internet with a modem I get a good speed but I loose a lot of packets. (time response for ping of 20 sec is normal).

I have tried to change the clock options but this doesn't matter. I have also changed the frame types, no solution.

Does anyone have an idee what I'm doing wrong, or what configuration has to be made. Does anyone know what I can do for debugging.


Rene van Wolferen


Re: Trouble with modem connection on CES circuit

The speed decreases due to the protocol stack sometimes. Based on the application some times the IPX data will slow down the modem connection. You can use some of the debug commands given in the following document. Use modemcap commands to configure the modem and then used debug to find the problem.

There is a good document on the debug commands of Modem and also on "Troubleshooting Modems" as given below:

Modem debug commands.

Troubleshooting Modems

Community Member

Re: Trouble with modem connection on CES circuit

Thanks for your information, but I'm using external modems and not a modem on the 7204 router. So I was wondering if I can troubleshoot the CES module and the defined pvc.


Rene van Wolferen

CreatePlease to create content