The wireless team must configure a new voice SSID for optimized roaming across multiple WLCs...

For optimized roaming across multiple Wireless LAN Controllers (WLCs) with Cisco 8821 IP phones, two critical settings must be configured. First, configuring mobility groups between WLCs (Option A) allows for seamless inter-controller roaming by establishing mobility tunnels between controllers, enabling them to share client security context, preventing re-authentication when a phone roams from an AP on one WLC to an AP on another. Second, using Cisco Centralized Key Management (CCKM) for authentication (Option B) reduces the time required for re-authentication during roaming from a full 802.1X exchange to a single-message re-key process. CCKM stores the wireless security keys at the WLC level, enabling rapid key re-derivation during roaming without contacting the RADIUS server. AP groups (Option C) control SSID and VLAN assignments per AP cluster but have no impact on inter-controller roaming. AVC profiles (Options D and E) control application visibility and QoS marking — marking voice as best effort (Option E) would actually degrade rather than improve voice quality. Reference: WLSD Study Guide — VoWLAN Mobility Optimization, CCKM Configuration, Mobility Group Design for Multi-Controller Deployments.