VPN on host machine breaks guest's connection

[alkalifly]

Whenever I connect to the VPN for my school (using the Cisco VPN client version 4.9.00) the internet connection to the guest machine (windows xp) gets killed. This will happen with both host-only networking and bridged networking.

When I do host-only networking, I am able to connect the guest to the internet by turning on Internet sharing on the Mac and manually assigning the IP address in Windows so that the router number is the same as the Mac's IP address and the DNS servers are the same as the one used by the Mac. But then as soon as I switch on the VPN service on the Mac, the Window's guest gets disconnected.

When I do bridged networking, I have the Window's guest connect to the internet using the Airport adapter, and I use DHCP so that Windows gets assigned its own IP address by my router. It seems that in this case, it should not matter what kind of connection my host machine has, but nonetheless as soon as I connect the Mac to the VPN, the guest is no longer able to get internet service. The connection is not totally broken, because I can still access shared folders.

It seems that this must be a bug, perhaps with Parallels or perhaps with the Cisco VPN client, or perhaps I am just setting it up wrong. Either way, I would appreciate any suggestions on what I should try doing to fix this or whether it is indeed a bug and will be sorted out.

Thanks!

 

[alkalifly]

Some more detailed info that may help in understanding this; here are the two different situations I experience:


Stiuation A: I am doing a bridged connection, where the host and the guest both have unique IP addresses assigned by my router using DHCP. As soon as I connect the host to the VPN, the guest loses its internet connection. I can still connect to shared folders on the Mac from within the windows environment, but from within the Mac I am NOT able to connect to any of the shared windows directories.

Situation B: I am doing a host-only network, where the guest gets connected via internet sharing from the Mac. Connecting the host to the VPN also kills the internet to the guest. I am still able to connect to shared folders on the MAc from within the windows environment, and this is consistent with situation A above. However, I am also still able to connect to shared Windows folders from within the Mac, which is INCONSISTENT with situation A above.

Perhaps this information will shed some more light on my problem?

Meanwhile, is there anyone out thee who is successfully connecting their HOST machine to a VPN and maintaining all communication between the guest and host? If so, please let me know how you set it up so that I can try to do the same...