A client organization is investigating deploying IP communications. It has a traditional huband- spoke Frame Relay WAN. It has five remote sites, and the WAN link speed for each location is 512 kbps. The WAN supports typical IP-based applications, but the client will also be rolling out a new ERP application that will be considered mission critical. Which three QoS mechanisms will be useful in redesigning the WAN to support the mission-critical application and IP communications? (Choose three.)