/mcpBit 4 = Throughput [T] (0 = Normal; 1 = High) • Bit 5 = Reliability [R] (0 = Normal; 1 = High) • 000000XX Bits 6, 7: ECN These two sections discuss two ways in which classification and marking are done. Voice Dial Peers to Classify and Mark Packets With Cisco VoIP gateways, you usually use voice dial peers to classify the VoIP packets and mark the IP Precedence bits. This configuration shows how to mark the IP Precedence bits: dial−peer voice 100 voip destination−pattern 100 session target ipv4:10.10.10.2 ip precedence 5 In the example above, any VoIP call that matches the dial−peer voice 100 voip command has all of its voice payload packets set with IP Precedence 5. This means that the three most significant bits of the IP ToS byte are set to 101. dial−peer voice 100 voip destination−pattern 100 session target ipv4:10.10.10.2 ip qos dscp ef media ip qos dscp af31 signaling In the example above, any VoIP call that matches the dial−peer voice 100 voip command has all of its media payload packets (voice packets) set with Expedited Forwarding (EF) bit pattern 101110. All the signaling packets are set with AF bit pattern 011010. Note: The ip qos dscp command is supported since Cisco IOS® Software Release 12.2(2)T. The IP Precedence is no longer available in Cisco IOS Software Release 12.2T. However, the same is achieved by the ip qos dscp command. IP precedence 5 (101) maps to IP DSCP 101000. For more information, refer to Classifying VoIP Signaling and Media with DSCP for QoS. Modular QoS CLI to Classify and Mark Packets The recommended classification and marking method to use is the modular QoS CLI. This is a template−based configuration method that separates the classification from the policy. This allows multiple QoS features to be configured together for multiple classes. Use a class−map command to classify traffic based on various match criteria and a policy−map command to determine what needs to happen to each class. Apply the policy to incoming or outgoing traffic on an interface by issuing the service−policy command. This configuration example shows how to use modular QoS CLI to classify and mark packets: access−list 100 permit udp any any range 16384 32767 access−list 101 permit tcp any any eq 1720 ! class−map match−all voip match access−group 100 class−map match−all control match access−group 101 ! policy−map mqc class voip set ip precedence 5 class control set ip precedence 5