At least one person (me) who doesn't! Sadly there isn't time to become knowledgable about everything, and I never found network administration very interesting anyway.
Which OS are you running?
Yep and here is a graph of usage:
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If not, it can be done using Linux's tc command.
How do you do it in Windows?
Do it at the router. It really helps if your router supports open-source Linux firmware.