Here is a neat trick to limit the amount of bandwidth you get from a specific IP or web address. I setup a box for my last company that used this technique to simulate sever and client being in different locations, great for performance testing. It uses a BSD command called ipfw or IP Firewall, which allows you to create pipes and queues to simulate any sort of network conditions. In a terminal type the following, replacing the x’s with an IP address:
ipfw add pipe 1 ip from xxx.xxx.xxx.xxx to any
ipfw pipe 1 config bw 5000kbit/s
Now you will get a maximum of 5000 Kbit/s form the IP address you entered. You don’t even have to be root to do this.
You can also use this to limit say the amount of bandwidth you give a particular IP address, great for when people are leeching off you, just swap from and to. This setup is an example of Dummynet.