1. CHINACOM 2006, Beijing, China26 Oct 2006 Osmosis in Pocket Switched Network Pan (Ben) Hui University of Cambridge Computer Laboratory Pan.Hui@cl.cam.ac.uk Jeremie Leguay, Jon Crowcroft, James Scott, Timur Friedman, Vania Conan

2. CHINACOM 2006, Beijing, China26 Oct 2006 Outline Pocket switched networks Osmosis scenario Osmosis analogy Penalty-based osmosis Evaluation methodology Results and discussion Conclusion

3. CHINACOM 2006, Beijing, China26 Oct 2006 Pocket switched networks Give it to me, I have 1G bytes phone flash. I have 100M bytes of data, who can carry for me? I can also carry for you! Thank you but you are in the opposite direction! Don’t give to me! I am running out of storage. Reach an access point. Internet Finally, it arrive… Search La Bonheme.mp3 for me There is one in my pocket…

4. CHINACOM 2006, Beijing, China26 Oct 2006 Is there a packet in your pocket or are you pleased to see me?

5. CHINACOM 2006, Beijing, China26 Oct 2006 Applications Asynchronous, local messaging Automatic address book or calendar updates Ad-hoc Google File sharing, bulletin board Commercial transactions Alerting, tracking or finding people

6. CHINACOM 2006, Beijing, China26 Oct 2006 Osmosis scenario Large scale Intermittently Connected Mobile Ad hoc Networks – Hundreds, thousands or more – Delays from minutes to days Query-driven data migrations Data usually much bigger than queries – E.g. file sharing Multiple possible paths

7. CHINACOM 2006, Beijing, China26 Oct 2006 Osmosis analogy Pic from:http://web.educastur.princast.es

8. CHINACOM 2006, Beijing, China26 Oct 2006 Penalty-based osmosis Data follows the query traces to requesters Penalties on paths without traces Control flooding

9. CHINACOM 2006, Beijing, China26 Oct 2006 Evaluation methodology(1) CRAWDAD Wi-Fi data from Dartmouth college January 26th 2004 and March 11th 2004 (45 days) Replay traces

10. CHINACOM 2006, Beijing, China26 Oct 2006 Evaluation methodology(2) File popularities and queries – Zipf’s law USNET newsgroup survey, 145 answers File sizes – Zipf’s law – Distortion at 3M

11. CHINACOM 2006, Beijing, China26 Oct 2006 Results and discussion Close success rate to Epidemic Half medium accesses, data transferred Reasonable mean delay

12. CHINACOM 2006, Beijing, China26 Oct 2006 Conclusion and future work Reasonable good lookup satisfactory Much reduce in transmission cost, buffer utilization Packets erasure algorithm Further evaluations – Haggle iMote traces – MIT RealityMining traces

13. CHINACOM 2006, Beijing, China26 Oct 2006 Thank you! Pan.Hui@cl.cam.ac.uk Jon.Crowcroft@cl.cam.ac.uk