/mcpQuality of Service for Voice over IP Resource Reservation Protocol 25 QoSVoIP.mif The default dial-peer configuration requests and accepts best-effort QoS for VoIP calls. This translates to the gateway not initiating an RSVP reservation for the call because IP provides best-effort service by default. The other two service alternatives are controlled-load or guaranteed-delay QoS. These two services require RSVP signaling; they are requested using the req-qos dial-peer configuration command. The acceptable QoS controls how strict or loose the CAC criteria should be; you configure the acceptable QoS controls by using the acc-qos dial-peer configuration command. We recommend that you configure the originating gateway and the terminating gateway to request and accept guaranteed delay. Sometimes you can configure the implicit dial peer matched on a terminating gateway to request and accept best-effort QoS. This dial peer takes effect when there is not an explicit dial peer match. Configuring Local Gateway Resources if CAC Fails As mentioned earlier, you can configure a voice gateway to take different actions if admission control fails. The first alternative is to have the gateways signal the user or the switch that delivered the call with a fast busy signal or a disconnect cause. If the call was delivered to the gateway by an ISDN switch, you can tune the Q.931 disconnect cause to guarantee that the switch handles calls correctly. A “QoS unavailable” (49) cause is returned by default when an ISDN call fails CAC because of the requested and acceptable QoS configured. You can modify this cause with the isdn network-failure-cause interface configuration command or isdn disconnect-cause interface configuration command. The current implementation of the isdn network-failure-cause command overrides the value configured using the isdn disconnect-cause command. ip route 0.0.0.0 0.0.0.0 10.10.1.2 ! voice-port 1/0:23 ! dial-peer voice 100 pots destination-pattern 2...... no digit-strip direct-inward-dial port 1/0:23 ! dial-peer voice 300 voip destination-pattern 3...... session target ipv4:10.77.39.129 req-qos guaranteed-delay acc-qos guaranteed-delay ! line con 0 line aux 0 line vty 0 4 ! end This example shows a complete voice gateway configuration that highlights the commands for configuring CAC using RSVP. The voice gateway can act as an originating gateway and terminating gateway with this configuration. We have not prioritized voice signaling in this example. Configuration Example 10: Deploying CAC Using RSVP (continued)