410 Chapter 11: Designing a Unity Solution
should define this, but there are other support considerations as well. For instance, if you
do a phased migration as a part of your design, indicate any specific support requirements
for that design. Who do subscribers call for problems? Who do your tech support engineers
contact for operational issues during each phase of the migration? How does moving from
legacy voice messaging to unified messaging affect how subscribers are supported? Your
usage analysis should indicate a considerable number of support issues and concerns that
you need to address in your design, implementation, and operations. Document the expec-
tations and any support or operational standards that each Unity server should adhere to.
Criteria for Implementation
When you have your high-level and low-level design documents finalized and signed off
on, you will want to start extracting the low-level information to put together your imple-
mentation plan. Your design documentation should provide all the information that you
need to devise a sound implementation plan. As stated earlier, if it does not, you probably
need to go back and revise your design.
For more information regarding implementation, see Chapter 16, “Installation.
Summary
This chapter discussed the Unity design process from start to finish. It took you step by step
through the key steps of the initial stage, the presales stage.
In the planning stage, you really find out about how a Unity pilot might go. In this stage,
you gather all your data through capacity planning, site surveys, and usage analysis. The
planning stage is essential for putting together a sustainable design for Unity.
The design phase is split in two. The first part involves restating your preliminary design by
defining the high-level design. The high-level design also should reference all your source
data so that you have a recorded audit trail up to this point in the process. The second part
involves the low-level design detail.
Your final goal is to use all the data collected from the planning stage along with your high-
level design to develop your low-level design.
Because the low-level design is your goal, it should be detailed. It should cover every
important aspect of a Unity server installation, including placement next to the messaging
servers that it services and all server-specific details, such as server names, IP addresses,
accounts used to access the server, and configuration details. The low-level design should
contain all information necessary to develop an implementation plan for any Unity deploy-
ment, large or small. This includes both detailed documentation and detailed diagrams for
each Unity installation.
Summary 411
This design process is repeatable in the sense that, if you follow the steps outlined, you
should be able to come up with a sustainable design for Unity. For smaller deployments
(with only a few Unity servers), your low-level design might not be as lengthy, but it should
be as thorough. Just remember that smaller deployments have the same design needs as
large-scale designs.

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