Question : Effective bandwidth for a WAN Link

What is the effective bandwdith that I could use for a 2M internet line ? What is the normal overhead for on a WAN link  ? Is there a rough ratio to estimate the effective bandwidth that I can use ?

Answer : Effective bandwidth for a WAN Link

You calculate what is called the Bandwidth Delay Product (BDP) and here is one of many on-line calculators:

     http://www.speedguide.net/bdp.php

However with such a low RTT and "low" bandwidth Windows default window size is fine.