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During the network design, an implementation plan is created, as detailed in the next section.
Creating, Documenting, and Executing an Implementation Plan
An effective, documented, implementation plan is a result of good processes and procedures during network
design, deployment, and performance testing. This section describes approaches to creating an
implementation plan and its associated documentation.
Approaches to Creating an Implementation Plan
There are two approaches to implementing changes to a network: using an ad hoc approach or using a
structured approach.
In an ad hoc approach, the network engineer identifies the need for a change, such as a routing protocol
implementation, and implements the solution without planning any of the tasks. The many tasks such as
connectivity, addressing, routing, and security are implemented and configured as required. New equipment
may be added, and new offices may be deployed. With such an approach, it is more likely that scalability
issues, suboptimal routing, and security issues can occur. A good implementation plan is required to avoid
such difficulties.
In a structured approach, the network engineer identifies the need for a network upgrade (for example, a
new routing protocol implementation) and starts with planning as the first step. Based on the existing
topology, all potential changes are reviewed, and many considerations are taken into account. The design
and implementation plan are completed, and may include a new topology, an IP addressing plan, a solution
to scalability issues, a link utilization upgrade, remote network connectivity, and changes to other network
parameters. The design and implementation plan must meet both technical and business requirements. All
details are documented in the implementation plan before the implementation. After the successful
implementation, the documentation is updated to include the tools and resources used, and the
implementation results.
Many models and methodologies used in IT define a lifecycle approach using various processes to help
provide high-quality IT services. Network implementation, including an implementation plan, is just one part
of these models. The following are some examples of these models:
• The Cisco Lifecycle Services approach defines the minimum set of activities needed to help
customers successfully deploy and operate Cisco technologies and optimize their performance
throughout the lifecycle of the network. The Cisco Lifecycle Services approach defines six phases in
the network lifecycle and is referred to as the Prepare, Plan, Design, Implement, Operate, and
Optimize (PPDIOO) model. The implementation plan is part of the Design phase; implementation is of
course part of the Implement phase.
• IT Infrastructure Library (ITIL) is a framework of best practices for IT service management,
providing high-quality IT services that are aligned with business requirements and processes. The
implementation plan and implementation are part of ITIL best practices.
• The Fault, Configuration, Accounting, Performance, and Security (FCAPS) model is defined
by the International Organization for Standardization (ISO) and defines the minimum set of
categories needed for successful network management. Five different categories are defined: Fault
Management, Configuration Management, Accounting Management, Performance Management, and
Security Management. The implementation plan and implementation are part of the Configuration
Management category.
• The Telecommunications Management Network (TMN) model is similar to the FCAPS model
and defines a framework for the management of telecommunication networks. The
Telecommunications Standardization Sector (ITU-T) took the main aspects of the FCAPS Model and
refined it to create the TMN framework. The implementation plan and implementation are one of the
building blocks within the framework.