/mcpQuality of Service for Voice over IP Resource Reservation Protocol 29 QoSVoIP.mif Figure 8 RSVP Support for LLQ on Point-to-Point Interfaces Cisco IOS Release 12.1(5)T introduced RSVP support for LLQ on Frame Relay PVCs. In this case, each PVC has its own queueing structure with a PQ and a CBWFQ system. At the interface level, a FIFO queue is set up unless you have enabled FRF.12 fragmentation. In that case, a dual FIFO system is set up with a high priority queue and a low priority queue. The high priority queue receives the PQ traffic from all PVCs plus Layer 2 control traffic. The low priority queue receives all other traffic from all PVCs. Remember that Frame Relay traffic shaping (FRTS) is required for Frame Relay circuits whether FRF.12 fragmentation is enabled or not. FRTS provides the back-pressure mechanism to detect congestion per PVC. Support for ATM PVCs is available in Cisco IOS Release 12.2(1)T. Deploying RSVP Support for LLQ You enable RSVP support for LLQ by default for voice flows on interfaces where RSVP and WFQ are enabled. You need not explicitly configure priority queues for voice packets. You can configure a custom priority queue profile using the ip rsvp pq-profile global configuration command. Configuring the profile as ip rsvp pq-profile voice-like restores the default behavior. The default priority queue profile uses a token rate of 12,288 bytes per second (approximately 98 kbps), a bucket size of 592 bytes, and a peak rate equal to 110 percent of the token rate (13,516 bytes per second or approximately 108 kbps). These parameter values support all possible codec configurations on voice gateways running IP RTP Priority Classification RSVP Class Priority Class 1 Class 2 Class Default Default Unreserved Classification Reserved Queues Priority Queue Scheduler Non-Voice Flow Voice Flow Reserved Queues Reserved Queues Reserved Queues 60096