user who use gprs can't access vpn,help!

[jeff.lee]

I am a user of China Mobile,I use GPRS wireless card to access internet,the old IOS of pix is 6.2x,because the IP address I get from ISP is like 10.x.x.x,I can't login my vpn server,After I upgrade the ios to 6.3x,I can log in the VPN(I know it's the "IPSEC through NAT" problem,so I upgrade the IOS),but I can't access even ping anything(such as my sap server,ftpserver),why?someone can help me?thanks

[hadbou]

This could be due to an assymetrical route in the network.

The concentrator sends out keepalive messages to the vpn clients, the

clients are responding, but not all the packets are being received back by the concentrator.

The concentrator then kills the link as it has not heard from the vpn client.

To conform this you can try to find out if the keepalives are being recieved on both sides.