Chapter 3, "Large-Scale Enterprise Requirements for IP Telephony," presented the XYZ, Inc. current network scenario and its high-level requirements for its future IPT network. Typically, customers provide these requirements in the Request for Proposal (RFP); otherwise, you can gather the requirements by meeting the voice architecture group in the customer organization. Understanding these requirements is critical to planning and designing a scalable and optimized IPT network.
Before you begin studying the planning phase, you need to understand the approach that we have taken to analyze the network infrastructure of XYZ in the planning phase.
The network infrastructure topologies of XYZ that were presented in Figures 3-2 and 3-3 show that the network is designed with full redundancy, that all network elements are Cisco switches and routers, that all devices understand QoS, etc. This topology is 100 percent ready to deploy IP Telephony (IPT). You will not find a network like this in the real world; instead, you will see networks that pose many challenges. Some of the common challenges are the following:
Networks that are deployed with non-Cisco switches—you are required to provide a solution to deploy Cisco IPT products
Switches that do not understand Layer 3 QoS
Switches that cannot provide inline power to Cisco IP phones
Networks that are deployed without following the recommended designs/best practices
To provide you with answers to some of the preceding challenges, we could have introduced some of these problems into the XYZ network. However, doing so would have made it harder to keep up with the chapter flow. Hence, the approach taken is as follows:
Describe the best practices in making the network infrastructure ready to support IPT
Provide alternate solutions and suggestions for commonly faced problems and challenges, such as those described in the preceding list, at appropriate places in the chapter
This chapter guides you through various tasks involved in the planning phase and discusses the best practices and the steps you need to follow at every layer of the network to make the network infrastructure ready to run the Cisco IPT solution.
To complete the planning phase for XYZ, this chapter uses the information presented in Chapter 3 along with the input provided by the customer to the following two questionnaires:
Network Infrastructure Analysis Questionnaire found in Appendix B, "IPT Planning Phase: Network Infrastructure Analysis Questionnaire".
Telecom Infrastructure Analysis Questionnaire found in Appendix C, "IPT Planning Phase: Telecom Infrastructure Analysis Questionnaire".
The first step in the planning phase is to understand the high-level business and technical expectations and requirements for the future IPT network, which include the following:
Company vision, goals, and forecasted growth
The plan for voice and data networks over the next 3 to 5 years
Deployment and timing
To simplify the discussion for this case study, assume that XYZ expects its workforce to grow 5 to 10 percent every year. XYZ requires that the new IPT system must emulate the functionality of the current PBX, voice-mail, and application systems, be scalable, and provide additional services and features that improve employee productivity. The new technology update project at XYZ received approval from the company's financial board to support the funding for the IPT project, and there are no major budget constraints.
After you understand the high-level business and technical expectations of the customer, the next step is to conduct meetings with the engineers and architects in the LAN, WAN, IT, legacy PBX, legacy voice-mail, and applications network groups. During these meetings with the various groups, you should make sure that the high-level requirements that you received from the customer in the RFP are accurate. Most importantly, make sure that you understand how the customer's existing network infrastructure is built so that you can identify the gaps in the infra-structure that need to be filled to support the converged traffic.