network environment is that:
ASA ----- Internet -------C2811
ASA connect Internet by ISP (special line), and has an fixed public address(eg: 221.x.x.x)
C2811 connect Internet by ISP (ADSL line), it will dial by PPP, and is assigned an private address.(eg:10.x.x.x, address is not fixed)
The private address will NAT by ISP to access Internet. (global public address is not fixed also)
Now we need create site to site vpn, between ASA and C2811. How to do it? Thank you very much.