Name three types of CAC.
Three types of CAC include local CAC, measurement-based CAC, and resource-based CAC.
What CAC mechanism would you use to guarantee enough bandwidth for the duration of a call?
You could use RSVP, which reserves bandwidth on a call-by-call basis and rejects calls when any router in the path is unable to provide sufficient resources.
How are dial peers configured to be part of the same hunt group?
You can use a destination pattern that points the dial peers to the same phone numbers, and designate a preference value to control their order of use.
What is the difference between LVBO and AVBO?
LVBO monitors router interfaces and makes the busyout decision based on the state of the interface. AVBO sends a probe to measure network congestion and make its busyout decision based on the results of that probe.
Which CAC mechanism, other than AVBO, uses probes in making its call admission decision?
PSTN fallback also uses probes to make its call admission decision.
What is TEHO used for, and what are two issues with its use?
TEHO is used to minimize long-distance toll charges. Issues with its use include dial plan complexity and regulatory restrictions.
What are some differences between gateway-controlled RSVP and CallManager-controlled RSVP?
You can use gateway-controlled RSVP only with gateway protocols that have dial peers, because it requires some configuration under the dial peers. The gateway makes the CAC decisions based on its RSVP policy configuration.
You can use CallManager-controlled RSVP with all gateway protocols because it does not require dial peer configuration. RSVP policy configuration is done on CallManager, and CAC decisions are controlled by CallManager. CallManager-controlled RSVP uses SCCP to communicate with a media resource called an RSVP agent on the gateway.
Given the following dial peers, which would the gateway use first? Second? Third?
dial-peer voice 2200 voip
session target ipv4:10.20.25.1
dial-peer voice 2201 voip
session target ipv4:10.20.26.2
dial-peer voice 2202 voip
session target ipv4:10.20.27.3
Dial peer 2201 would be the most preferred. It has the default preference value of 0, which is the highest priority. (Lower preference values have higher priority.) Dial peer 2200 would be used second because its preference value is 1, and dial peer 2002 would be least preferred because it has the highest preference value.
Part I: Voice Gateways and Gatekeepers
Gateways and Gatekeepers
Part II: Gateways
Media Gateway Control Protocol
Session Initiation Protocol
Connecting to the PSTN
Connecting to PBXs
Connecting to an IP WAN
Influencing Path Selection
Configuring Class of Restrictions
SRST and MGCP Gateway Fallback
Using Tcl Scripts and VoiceXML
Part III: Gatekeepers
Part IV: IP-to-IP Gateways
Cisco Multiservice IP-to-IP Gateway
Appendix A. Answers to Chapter-Ending Review Questions