The WLAN configuration exhibit shows the Quality of Service (QoS) profile set to Platinum (voice) and, most critically, the WMM Policy set to Required. The Required setting mandates that any client device attempting to associate with this WLAN must support and use Wi-Fi Multimedia (WMM). WMM is the Wi-Fi Alliance's interoperability certification for a subset of the features defined in the IEEE 802.11e standard, which provides QoS enhancements to the 802.11 MAC layer. Therefore, for a VoWLAN phone to connect to this network and have its voice traffic prioritized correctly, it must support both the 802.11e standard and its WMM implementation.

A. TSPEC: This admission control mechanism is not required by this configuration, as indicated by the 7920 AP-CAC setting being disabled.

B. SIFS: Short Interframe Space is a fundamental timing interval in the 802.11 protocol used by all devices; it is not a special feature for QoS.

E. APSD: Automatic Power Save Delivery is a power-saving feature within WMM. While beneficial for VoWLAN phones, it is not the core requirement for establishing a QoS-prioritized connection.

1. Cisco Wireless LAN Controller Configuration Guide

Release 8.5

"Configuring QoS" Chapter

"Configuring QoS per WLAN (GUI)" section. This document states

"From the WMM Policy drop-down list

choose... Required—Clients must support WMM. Clients that do not support WMM are not allowed to associate with the WLAN." This confirms the mandatory nature of WMM support.

2. Cisco Enterprise Mobility 8.5 Design Guide

"Voice over WLAN Design and Deployment Recommendations" Chapter

"QoS for VoWLAN" section. This guide clarifies the relationship between the standards: "WMM is a certification by the Wi-Fi Alliance of a subset of the IEEE 802.11e amendment... Cisco recommends that you configure the voice WLAN for Wi-Fi Multimedia (WMM) and configure the QoS profile to Platinum." This directly links the Platinum profile

WMM

and the underlying 802.11e standard as essential for VoWLAN.

3. IEEE Std 800-4302.11™-2020

"IEEE Standard for Information Technology—Telecommunications and information exchange between systems Local and metropolitan area networks—Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications

" Clause 9.4.2.57 "WMM/WME Parameter Element". This section of the official standard defines the WMM Information Element that WMM-capable stations (clients) use to advertise their QoS capabilities

which is a requirement for associating with a WMM-enabled AP.