Cisco client-initiated L2TP tunnel over L2TP tunnel

Hi, everybody.

I’m working for an ISP and we are trying to set up a client-initiated L2TP tunnel over another client-initiated L2TP tunnel (with one Virtual-PPP interface over another) but it doesn?t work, topmost L2TP tunnel doesn?t come up.

We are trying to do this to simulate a client-initiated L2TP tunnel (with a Virtual-PPP) over a L2TP ADSL (with a Dialer), since we don?t have at the moment a L2TP ADSL to test with.

Has anyone of you been able to make such a thing? Do you know if it is possible? I have been doing some researching in google, but I haven?t found anything like this.

Thanks in advance

David