how to limit the maximum no. of request to my website in asp

Question

Hi sir,
    Tell me the steps to limit the maximum no. of request to my website in asp.net c#. Suppose if i set 100 person can access my website at the same time, if new user visit
my website it has to show "the server is temporarily busy please try again after a moment". Kindly give me the solution for this problem.



[Hint : I need to set only 100 online users to enter the website , if the 101th user enter the website it has to show error like "Server is busy". I need to avoid network
traffic for my website request]