Woh! A deep dive, but quite insightful. Gives the reader an appreciation that QoS does NOT happen by magic!
After reading few online posts about wireless QoS, I felt it is worth to spend some time to understand what’s going on packet level. So this will be the first part of wireless QoS related posts. I have used following lab set up for this exercise.
In this part, I will look at how QoS parameter (primarily DSCP/COS tag) of a packet change when it traverse from wireless client (C7921) to Wired client (PC). Before looking into the packet capture this is my basic understanding how it should work.
1. If wireless client device is WMM capable it will classify its application traffic into 8 user priorities(UP) & four Access Categories (Voice-VO, Video-VI, Best Effort-BE, Background-BK).In this case RTP media traffic with DSCP EF ( mark as WMM_UP of 6) & tcp control traffic with DSCP CS3 (WMM_UP of 4).
2. When AP receive this traffic, it will encapsulates the…
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