rate_limit , police_rate , fall_through ?

Rate_Limit_Rate = 128, Rate_Limit_Burst = 20000, Police_Rate = 128, Police_Burst = 20000, what does the 128,20000 mean ? if i want to restrict download speed at 10.0k and upload of 5k for each user? what value should be for rate_limit and police_rate ? what is fall_through? i cant find wiki on this. does anyone has any reference url? --------------------------------- Love cheap thrills? Enjoy PC-to-Phone calls to 30+ countries for just 2¢/min with Yahoo! Messenger with Voice.