I've got a surprisingly large number of requests for my "Unterstanding QoS" presentation on last Thursdays SWINOG 18 meeting. I've made it available as PDF on my website:

http://www.networx.ch/Understanding%20QoS%20by%20Andre%20Oppermann%20-%20200...

Please don't hesitate to book be for an hour, day or more to go into more detail or to get an independent review of your current QoS concept.