McDewey

Quality of Service for Voice over IP Traffic Shaping 15 QoSVoIP.mif drop VoIP traffic if contracts are violated. Therefore, you need to control transmission rates into a Frame Relay cloud so that you can control which packets get dropped and which packets receive priority servicing. Figure 3 shows an example of a typical Frame Relay network without traffic shaping. Figure 3 Frame Relay Network Frame Relay Traffic Shaping Example The following configuration example shows how to configure Frame Relay traffic shaping: Frame Relay, ATM Central Site T1 T1 Remote Sites Result: Buffering that will cause delay and, eventually, dropped packets 128 kbps 256 kbps 512 kbps 768 kbps 60061 Configuration Example 8: Frame Relay Traffic Shaping interface Serial 0/1 no ip address encapsulation frame-relay frame-relay traffic-shaping ! interface Serial 0/1.64 point-to-point ip address 10.14.96.2 255.255.255.252 frame-relay interface-dlci 128 class voice ! map-class frame-relay voice no frame-relay adaptive-shaping frame-relay cir 256000 frame-relay bc 2560 frame-relay mincir 256000 In this example, Frame Relay traffic shaping is enabled on the main serial interface 0/1 and DLCI 128 is placed into a voice shaping class. Map class voice sets up a CIR of 256000 bps and a committed burst rate (Bc) of 2560 bits. This configuration means that the router will send 2560 bits every 2560/256,000 seconds (10 ms) and queue any excess bursts. The minimum CIR is set to the same value as CIR, and adaptive shaping is disabled. The Frame Relay excess burst (Be) value is not set and therefore defaults to 0, preventing any bursting over CIR. This is the recommended configuration for traffic shaping when carrying VoIP.