Wi-Fi · WMM & QoS
Generate Cisco Catalyst 9800 WLC QoS profile for voice/video SSIDs — Platinum, WMM required, DSCP-to-UP mapping, Apple Fastlane, and Call Admission Control.
Wi-Fi is the weak link for voice quality in most enterprises. Done right, 9800 WLC + WMM + Fastlane delivers carrier-grade voice over Wi-Fi. Done wrong, every microwave oven kills a call.
Wi-Fi doesn't use DSCP on the air — it uses User Priority (UP) in the 802.11e frame. The WLC translates between DSCP and UP using a map that you must control. The Cisco default maps voice DSCP (EF = 46) to UP 6 (voice), which is correct. What gets confused is when enterprise Windows and Mac clients mark DSCP on the wire but the AP driver only looks at 802.11e UP — you end up priority-queuing by application only, not by marking.
Cisco's 9800 WLC exposes four pre-built QoS profiles: Platinum, Gold, Silver, Bronze. Platinum is for voice — maps DSCP-EF → UP6, allows WMM, and participates in airtime fairness. For voice SSIDs, always pick Platinum in the policy profile.
Apple Fastlane is an extension that requires DSCP markings from a managed Apple device (MDM-pushed) to be trusted end-to-end from the iOS app through the AP to the wired network. Enable it if you use Jabber for iPhone or the Webex App on corporate-managed iOS.
Not usually. Cisco recommends leaving CAC off in favor of proper RF planning (20% airtime headroom, one call per AP per radio minimum, 5 GHz preferred) and WMM admission control handling of 802.11e TSPECs. Only enable CAC if you have known airtime overload in auditorium-style deployments.
The AP only sees DSCP if the traffic arrives at the WLC un-tunneled. In FlexConnect (local switching), the AP tags 802.11e UP but may not honor DSCP on egress. Use qos trust dscp on the wired port of the AP's switch.
Rule of thumb: 8 calls per 2.4 GHz radio, 12 calls per 5 GHz radio at 20 MHz. Wi-Fi 6/6E with OFDMA can double this because of scheduled access.
Platinum profile, WMM required, Fastlane enabled. Policy profile maps to VLAN 220 (voice). Clients: Webex App on iPhone (marks EF when Fastlane policy is signed).
Platinum with static CAC at 50% reservation. Vocera requires CAC-aware APs. Disable 802.11b/g/n-2.4 GHz entirely on this SSID; 5 GHz only, with DTIM 1.
Gold profile (not Platinum — guest shouldn't get voice priority over corporate). WMM allowed. DSCP re-marked on the WLC egress to AF31 regardless of client marking.