Cisco IP Telephony: Planning, Design, Implementation, Operation, and Optimization [Electronic resources] نسخه متنی

Chapter 4. Planning Phase

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 switchesyou 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".