Controlling congestion in high-speed networks is becoming more difficult because of large bandwidth-delay product. One aspect of such dif- ficulty is that we may not be able to utilize the large bandwidth marimally with current conser- rative nature of control. We show how much the current algorithms can fail to exploit larger bandwidth such as multi-megabits or gigabits per second. by contrasting its performance with that of an experimental aggressive algorithm. Then we suggest some directions for future research to make congestion control algorithms more aggres- sire without hurting the network stability.