1. Robust Content Delivery Network R92725016 周亦方 R92725050 莊豐源 R92725051 黃世翔

2. China U.S.A. Web servers Taiwan text movie picture HTTP Request cache

3. China U.S.A. Web servers Taiwan text movie picture HTTP Request cache

4. Terms  www.media.com : On-line media center www.media.com  www.cdn.com: Content deliver service www.cdn.com  DNS server of cdn.com:  GRM (Global Request Manager)  Configuration Manager  DNS (bind)  Agent  Cache (nodes)

5. DNS Query Format

6. DNS Response Format

7. System Diagram http://www.media.com/ http://www.cdn.com/movie/waterbaby.wmv – ButterFly, RFC 9999 Our core tech. !!!

8. DNS BIND GRM Config Manager 1. Mapping table 2. Agent DNS Server of cdn.com ISP DNS Query cdn.com 1.If the client domain exists in the table, GRM returns what it maps. 2. If it doesn’t exist in the table, GRM returns a list of randomly–selected servers and then starts agent for this domain, so that next user from the same domain will receive a better server list answers.

9. Domain Ex: 140.112.107 USER GROUP Ex: Taiwan, China, U.S.A Cache Ex: TW1, TW2, CN1… 140.112.107 -> Taiwan, U.S.A., China 169.237.198 -> U.S.A Taiwan, China Taiwan -> TW1, TW2, TW3 U.S.A. -> US1, US2, US3 China -> CN1, CN2 ….. Domain->Group Table: ….. Each cache is an object having many attributes such as IP, name, group, health… Group->Cache Table:

10. Goal  Domain -> Group: (content distribution) Using known facts or starting agent to place each domain in suitable group.  Group -> Cache: (load balance) Randomly assign a cache to each request.

11. Server-Choosing Algorithm  Use known facts: Ex: We know that 140.112.xxx.xxx is NTU domain. Then any IP from this domain will be served by caches in Taiwan.  Agent help: Using various methods to decide a group order for the unknown domain.

12. Agent Type 1. ICMP ping -> Round trip time (layer 3) 2. Traceroute -> hop count (layer 3) 3. DNS lookup round trip time -> DNS reverse lookup (layer 7) 4. Multicast to find the most available (any) Reference: Network appliance, Cisco, 麟瑞科技 The lower the layer, the less the noise. More accurate but is subjected to be banned.

13. Scenario ( 差別服務 ) 1. Users from different domains will get different lists of answers. User from 140.112.107 (Domain = Taiwan) User from 140.112.106 (Domain = U.S.A.)

14. Scenario ( 仰賴 browser) 2. If the first-selected server crashes, browser will automatically try the next one in the list. 1.TW1: 140.112.107.77 2.TW2: 140.112.107.178 3.US1: 140.112.106.66 User from 140.112.107 (Domain = Taiwan)

15. Scenario ( 仰賴自己最可靠 ) 3.TestHealth runs periodically to ensure that cache health states in Group -> Cache table is updated. 4.Here comes another user from 140.112.107 domain, and he will get a new server list.

16. Scenario ( 前人種樹 ) 5.If a user comes from an unknown domain, ex: 140.112.214, GRM returns a randomly chosen server list. 6.Then Config Manager starts PingAgent to decide a group order for this domain, and then updates Domain -> Group table.

17. Scenario ( 後人乘涼 ) 7.If another user comes from 140.112.214, since Config Manager has the prior knowledge of this domain, it simply returns the answer.

18. Conclusion  Using known facts and agent to update knowledge base. (AI learning)  Our butterfly model can be applied to almost any application because it is an overlay of DNS.  Popular Protocols (HTTP, FTP, …)  Streaming (RealNetwork, Windows Media Video, Apple QuickTime, …)  Mobile (WML, …)