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

Planning Phase

Planning is the first phase in the PDIOO lifecycle. A thorough execution of the planning phase tasks lays a solid foundation for the design of an IPT network.

One of the first important tasks in the planning phase is to understand the end customer's expectations and requirements. These fall into two main categories:

Business expectations and requirements

Technical expectations and requirements

Note

The customer usually provides the business and technical expectations and requirements in the RFP document. You should use the information presented in the RFP first and then consult the voice network architecture group, IT groups, or other groups in the customer's organization to obtain additional information.

From the business expectations and requirements point of view, you should understand the company's goals and vision and analyze how these relate to the future IPT network. More particularly, information that might help you to execute the project in a timely manner and complete it within the projected budget includes the company's goals for expansion in the next 4 to 6 years, its capital expenditures (CAPEX), its operational expenditures (OPEX), its return on investment (ROI), and its expectations regarding how long the project should take to plan, design, and implement.

From the technical expectations and requirements point of view, you should understand the company's current and future needs regarding IPT network features and functionality. These expectations and requirements include general features that are required in the IPT network, such as network redundancy, high availability, convergence, security, network management, application requirements, utilization, performance, scaling requirements, and so forth.

After you understand these high-level business and technical expectations and requirements, the next phase is to conduct a site survey. One of the most important tasks in the site survey is to meet the right groups of people (i.e., LAN group, WAN group, IP network group, legacy PBX and voice-mail network group, applications group, etc.). Establishing the right contacts helps you to quickly obtain accurate information pertaining to the network.

While conducting the site survey, you need to obtain details regarding the following:

Existing LAN infrastructure, such as the LAN topology, equipment deployed, and current LAN QoS policies

WAN infrastructure, such as the WAN architecture, WAN equipment deployed, existing QoS policies, traffic flows, bandwidth assignments, and link utilizations

Layer 3 and Layer 2 infrastructure

IP addressing scheme, including how network services such as Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS) are deployed

Directory and messaging architecture

Layer 3 routing and routed protocols used in the network

Legacy telephony and voice-mail infrastructure and telephony features such as paging, operator, night bell, call center, Music on Hold, etc. deployed in the network

Legacy dial plan configurations

Current utilization and performance for voice and data networks

Current network management infrastructure

Current day 2 support and operations support process

After you collect the information by conducting the site surveys, you should perform a detailed network infrastructure assessment to ensure that the network will support IPT, that new systems and applications will be compatible with existing systems and devices, and that the new IPT system will perform as planned. The infrastructure assessment should include details regarding gaps in the infrastructure that need to be filled to support IPT and recommendations to strengthen the infrastructure to support the converged network.

Proper execution of the planning phase will lead to the following:

Realistic expectations of the scalability, performance, and features of the new IPT system

A network infrastructure that is able to support the IPT traffic

Identification of proper resources to accelerate the rollout of the IPT deployment

An IPT network that is aligned with business needs

Successful integration with legacy PBX and voice-mail systems or complete migration to an IPT network

Deployment of IPT applications and their integration with existing applications

Chapter 4, "Planning Phase," covers the planning phase and various tasks involved. Appendixes B, "IPT Planning Phase: Network Infrastructure Analysis Questionnaire," and C, "IPT Planning Phase: Telecom Infrastructure Analysis Questionnaire," include Network Infrastructure and Telecom Infrastructure Analysis Questionnaires, respectively, that you can use to collect the information required in the planning phase and to perform the network infrastructure assessment and gap analysis.