robust scalability of routing system (2) difficult to get consensus even (esp) among routing experts: (akamai researcher bruce maggs, routing wksp www.net.informatik.tu-muenchen.de/wired/) 1. Where (if anywhere) is the congestion in the Internet? 2. How much capacity does the Internet have, and how fast is it growing? 3. How much traffic does the Internet core carry and what does it look like? 4. How fast is network traffic growing? 5. What will traffic patterns look like five years from now? 6. Can we scale the network to support the demands of users five years from now? 7. How much does/will it cost to increase network capacity? 8. Will stub networks soon be employing sophisticated traffic engineering mechanisms on their own, e.g, those based on multihoming and overlay routing? What impact might these techniques have? 9. What fraction of traffic are CDNs carrying? What effects derive from DNS tricks to route traffic?