Chapter 5. Creating a Physical Design
After creating a logical design, create the physical design, which consists of constructing a high-level network design and planning for capacity. This chapter provides information to assist you in formulating estimates for how much capacity your design needs. Use it as a general sizing guideline for estimating storage and memory for services.
We suggest that you approach this part of the architecture process with the objective of performing initial capacity planning, based upon estimated usage or industry averages. Also, plan to scale to maximum capacity, based on the ISP’s requirements.
Because of many unknown variables in an ISP’s environment and ever-changing traffic, load characteristics, and subscriber usage patterns, it’s unrealistic to calculate exact capacity amounts during the design phase. Aim for reasonable estimates that can later be refined using actual resource utilization data.
This chapter contains the following topics: