Advantages and disadvantages of the top-down and bottom-up implementation approaches

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The top-down and bottom-up approaches to deploying your identity management solution are provided to help you decide the best way to integrate identity management capabilities into your environment. Each approach has distinct advantages and disadvantages, as shown in Table 11.
Table 11. Pros and cons of the top-down and bottom-up implementation approaches Bottom-up approach Top-down approach
Summary

* High deployment coverage in early phases
* Earlier return on investment
* High visibility of organizational changes
* Higher impact to organization



* Tactical, limited coverage
* Delayed return on investment
* Lower impact to overall organization
* Higher deployment costs

Advantages

* User and business awareness of the product. Benefits are realized in the early phases.
* You can replace many manual processes with early automation.
* You can implement password management for a large number of users.
* You do not have to develop custom adapters in the early phases.
* Your organization broadens identity management skills and understanding during the first phase.
* Tivoli Identity Manager is introduced to your business with less intrusion to your operations.



* Your organization realizes a focused use of resources from the individual managed application.
* The first implementation becomes a showcase for the identity management solution.
* When the phases are completed for the managed application, you have implemented a deeper, more mature implementation of the identity management solution.
* Operation and maintenance resources are not initially impacted as severely as with the bottom-up approach.

Disadvantages

* The organizational structure you establish might have to be changed in a later roll-out phase.
* Because of the immediate changes to repository owners and the user population, the roll-out will have a higher impact earlier and require greater cooperation.
* This strategy is driven by the existing infrastructure instead of the business processes.



* The solution provides limited coverage in the first phases.
* A minimal percentage of user accounts are managed in the first phases.
* You might have to develop custom adapters at an early stage.
* The support and overall business will not realize the benefit of the solution as rapidly.
* The implementation cost is likely to be higher.