Scenario Two Answers

1. The company wants to provide voice services in a converged network.

2. The solution should provide reduced costs over the existing separate voice and data networks.

3. The technical requirements are as follows: Provide IP telephony over the data network.

Provide voice redundancy or failover for the remote sites. Prevent FTP traffic from impacting the voice traffic.

4. The technical constraint is as follows: Call-processing servers need to be located at headquarters.

5. There are 200 IP phones at headquarters, and 35 * 30 = 1050 remote IP phones, for a total of 1250 IP phones.

6. Propose the WAN centralized call-processing architecture with a CallManager (CM) cluster at headquarters.

7. Use low-latency queuing (LLQ) on the WAN links to give the highest priority to voice traffic. Then define traffic classes for regular traffic and FTP traffic. Make bandwidth reservations for the voice traffic and maximum bandwidth restrictions for the FTP traffic. Call Admission Control (CAC) is recommended to limit the number of calls from and to a remote site.

8. To prove that calls can run over the WAN links, implement a pilot site. The pilot would test the design's functionality over the WAN with or without FTP traffic.

9. Recommend the use of Survivable Remote Site Telephony (SRST) to provide voice services in the event of WAN failure, and reroute calls to the Public Switched Telephone Network (PSTN).

10. Figure 17-4 shows the diagram, which shows headquarters and two remote sites for clarity. This architecture is duplicated for all remote sites. Each site uses a voice router that is connected to both the IP WAN and the PSTN. SRST provides voice survivability in the case of WAN failure. A CM cluster is implemented at the headquarters. The CM servers are in the data center in a redundant network.

Scenario Three: Beauty Things Store 577

Figure 17-4 Headquarters and Two Remote Sites for Clarity

Figure 17-4 Headquarters and Two Remote Sites for Clarity

IP WAN Router/GW SRST Remote Sites


IP WAN Router/GW SRST Remote Sites


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