Quality of Service (QoS), in general, is probably one of the most difficult topics to digest. Combing QoS with wireless makes it even more confusing. Without good documentations, ones can easily find themselves lost in translation. In this article, we will look at QoS settings on Cisco Wireless LAN Controller (WLC), specifically regarding packet marking in central switching mode, and try to understand relationships among 802.1p, 802.11e, WMM, and AVC, through lab experiments. Wireshark will be heavily used in this lab to provide insight to packet headers.