Jang, Donghyun 2011/4/4 dhjang@mmlab.snu.ac.kr

1. The cache-and-forward network architecture for efficient mobile content delivery servicesin the future internetSanjoy Paul, Roy Yates, DipankarRaychaudhuri, Jim Kurose Jang, Donghyun 2011/4/4 dhjang@mmlab.snu.ac.kr

2. Table of contents • Introduction • System overview • CNF Protocol details • Performance summary • Conclusion

3. Introduction • Representative Future Internet research project • NSF FIND and GENI in the U.S. • FP7 Future Networks and FIRE in Europe • This paper presents the initial results of an NSF FIND project • The initial results focus on designing a clean-slate network architecture for efficient delivery of media content to mobile users

4. Why should we focus onmobile contents? • ~2.5 billion cell phones vs. ~500 million wired PC • Smart phones and PDA proliferate rapidly • The number of Internet transactions from mobile devices may be expected to surpass those from wired network PC’s over the next 5-10 years • Shift of end-users from wired to mobile VS

5. Why should we focus onmobile contents? • Internet usage pattern • Communication => contents service (delivery of large file) • Need next-generation Internet protocol service optimized to support media content delivery to mobile user

6. Why do we need new architecture? • Existing Internet protocols (e.g., TCP/IP) are not well-suited for mobile content services • TCP model assumes a contemporaneous source-to-destination path • Mobile users experience intermittent and unreliable access over wireless channels • TCP model was originally designed to support point-to-point data services • It is not suitable for multipoint content dissemination

7. Main idea • To solve the problems of TCP/IP architecture • Facilitate opportunistic transport on a hop-by-hop basis rather than end-to-end streaming of data • Hop-by-hop transport model implies large in-network storage (cache) of content files • This is basic idea of the cache-and-forward (CNF) network architecture

8. System overview –CNF and CNC router • Each node has a large storage cache • CNF router may either be wired or wireless, also mobile (especially, mobile CNF router refer to Cache and Carry (CNC) router) CNC

9. System overview –Pull & Push contents • Network serves two functions • Pull: Mobile end-user can request contents • Push: Content provider can push the content to one or more end-users

10. System overview –Pull contents • When mobile end-user can request contents • Contents Discovery • copies of the same content can be cached in multiple CNF routers in the network • Discover the CNF router with the desired content that is “closest” to the requesting endpoint S Content Content

11. System overview –Push contents • When content provider can push the content • Post Office (PO) • Edge of the wired core network • Holding and forwarding point for content to mobiles PO

12. System overview –The steps of pushing contents • The sender contacts a name resolution service that resolves the name of the mobile host to a set of PO nodes • The sender will forward the file to one or more PO’s using conventional point-to-point routing • These PO’s will “hold” the file until contacted by the mobile host to arrange delivery

13. System overview –package • Each query and content file is carried as a CNF packet data unit or package in a hop-by-hop fashion

14. CNF protocol details • Implemented as overlay network on IP network

15. CNF protocol details –Link layer • A link in the CNF architecture is a logical link between two adjacent CNF nodes • Consists of two components • Link Session Protocol (LSP) • Link Transport Protocol (LTP) • The choice of LTP will depend on the characteristics of the link

16. CNF protocol details –Network layer • Content discovery • Content-aware routing based on a content identifier (CID) • Routing content after content was discovered • Conventional (IP) address-based routing

17. CNF protocol details –Transport layer • Fragment very large files (10’s of GB) into smaller chunks (~100MB-1GB) before transporting End-host

18. CNF protocol details –NRS & FNRS • Name Resolution Service (NRS) • Map the name of an endpoint to its corresponding POs • File Name Resolution Service (FNRS) • Map a CID (content identifier) to corresponding attributes of the content • Attributes of the content • Content Hash, Content Creator, Content Access Rights, etc

19. Conceptual Flow Diagram

20. Performance summary • Simulation by using ns2 • Hop-by-hop vs. TCP performance • TCP is better than hop-by-hop in low load • Hop-by-hop is better than TCP in high load • Wireless multi-hop performance • The results show that significant throughput gains are possible with customized link layer protocols like CLAP instead of TCP • Content routing gains • Reduction of content retrieval time and traffic load

21. Conclusion • New approach to network design in response to growing needs for improved support for both mobility and content in the future internet • The design presented here is clearly preliminary and will be further refined