Note on ASA/PIX Firewall: To keep the office network of having uninterrupted Internet connection while establishing IPSec tunnel coming in from remote users, you want to keep the "isakmp nat-traversal" command. You may need to increase the value from 20 to 30 secs (or to any value other than default) to make the regular web traffic passing while remote user VPN in.
To keep the Internet access for the remote users while IPSec VPN into the Office Network, you need to use the "vpngroup split-tunnel" command. On this command, you need to associate it with the access list that control the encrypted traffic. In other word, you may use the same access list that is used in the "nat 0 (inside)" command.
