We have 2 independent networks and a few users in network A use remote desktop to get on a terminal server in network B. We set up an IPSec tunnel between the 2. As far as we can tell the bandwidths on either side aren't reaching their limits, so we haven't set up any dedicated bandwidth rules on the routers or firewalls.
When users on network A ping the public IP or private IP of the terminal server in network B, they get 100 ms responses. When on the server in network B and pinging back to network A, ping times are 200 ms.