Quite a few years ago, I setup tc to do a bit of traffic shaping on my home network. Instead of having a standard router, I have a Linux box with two network cards using iptables to do NAT. I connect my cable modem to one of the network cards and then I connect my home network to the other.

Way back, I found I had two problems - if I was doing something that did a lot of uploading (eg seeding a torrent), my download speed would tank because the tcp/ip packets were bogged down in the upload queue.

I also like to be able to ssh into my machine while away from home, and if I did that while uploads were going on, the ssh terminal was basically unusable.

Back then I discovered tc - it was able to make TCP control packets (ack's etc) and ssh related packets jump to the head of the queue, and the other upload stuff have a lower priority.

Looking back at the script I created now, I don't really understand what it is doing, but it remember it worked. I still run it today and just take it for granted.

I tested it by start a large upload while ssh'ed into the box from the internet - I turned off the tc rules and the terminal became unusably laggy, and then I turned the rules on and it worked perfectly.