Write a chapter of a book on introducing data center networking. Target audience is network engineer who took a basic course in computer networking but without specialized knowledge. The section to write is "Capacity and redundancy planning" (Assume reader have read last chapter and know the basic architectures). Outline:
- How to estimate bandwidth requirement (Give examples)
- Data center Tiers and how to provide network redundancy (illustrate in context of modifying an existing blade and spine architecture)
- Internet access options and data center interconnect (discuss things like dedicated lines from ISP, direct interconnect, multiple ISPs, continuing from the blade and spine architecture above)

Ensure each section is long enough and provide details.