There is an excellent primer on QOS written by Toastman who is the developer of one of the TomatoUSB forks at http://www.linksysinfo.org/index.php?threads/qos-tutorial.68795/. This should be required reading for anyone hoping to use QOS.
It's usually best to configure QoS with your upload speed set at 70% of your actual max speed. For example, if your upstream is 2 Mbits, set it to 1.7 Mbits in QoS. That will usually result in smoother performance when QoS has to kick in.
Is 1.7 Mbits 70% of 2 Mbits? #math
Making sure that credit goes where due, the exhausive tutorial on QoS that was attributed to me above was in fact from Toastman of TomatoUSB fame: http://www.linksysinfo.org/index.php?threads/qos-tutorial.68795/.
I have never set QoS up on my network...have no need for it...but did play around a bit with it and found this tutorial to be very helpful to understand exactly what QoS was doing. Of course, now I have forgotten it all...one of the viscitudes of the aging process.
Welcome To SNBForums
SNBForums is a community for anyone who wants to learn about or discuss the latest in wireless routers, network storage and the ins and outs of building and maintaining a small network.
If you'd like to post a question, simply register and have at it!
While you're at it, please check out SmallNetBuilder for product reviews and our famous Router Charts, Ranker and plenty more!