Figure 6: Regular vs Hybrid Spray and Wait routing in Rollernet. (Partial view of the topology at t=15s) Node without any copies Intra-group link Node with a least one copy Inter-group link (a) HYMAD: success within 15 seconds. (b) Spray-and-Wait: the copies stagnate around the source. It will take a total of 525 seconds to hit the destination. and-Wait. Further work includes more comprehensive testing against other real and synthetic mobility sce- narios. HYMAD is an example of a larger class of hybrid DTN-MANET routing protocols which can handle a very wide spectrum of networks that overlaps with those usually handled by either DTN or MANET. We believe that the first results that we obtained are en- couraging for further research in this direction. In par- ticular, other more elaborate DTN/MANET protocol pairs could conceivably be used for intra and inter- group routing and would be worth exploring. This work has been partially supported by the RNRT project Airnet under contract 01205 Acknowledgments References [6] B. Ducourthial, S. Khalfallah, and F. Petit. Algo- rithme de gestion de groupe pour les r´ eseaux ad hoc fortement dynamiques. In AlgoTel , May 2008. [7] K. Fall. A delay-tolerant network architecture for chal- lenged internets. In Proc. ACM SIGCOMM , 2003. [8] M. Grossglauser and D. N. C. Tse. Mobility increases the capacity of ad hoc wireless networks. IEEE/ACM Trans. Netw. , 10(4):477–486, 2002. [10] A. Lindgren, A. Doria, and O. Schelen. Probabilistic routing in intermittently connected networks. In Proc. SAPIR , 2004. [9] M. Grossglauser and M. Vetterli. Locating nodes with ease: Last encounter routing in ad hoc networks through mobility diffusion. In Proc. IEEE Infocom , 2003. [11] J. Ott, D. Kutscher, and C. Dwertmann. Integrating dtn and manet routing. In CHANTS ’06: Proceed- ings of the 2006 SIGCOMM workshop on Challenged networks , 2006. [12] R. C. Shah, S. Roy, S. Jain, and W. Brunette. Data mules: Modeling a three-tier architecture for sparse sensor networks. In Proc. IPSN , 2003. [13] T. Spyropoulos, K. Psounis, and C. Raghavendra. Spray and wait: an efficient routing scheme for inter- mittently connected mobile networks. In Proc. WDTN , 2005. [14] P.-U. Tournoux, J. Leguay, F. Benbadis, V. Conan, M. D. de Amorim, and J. Whitbeck. The accordion phenomenon: Analysis, characterization, and impact on dtn routing. In Proc. IEEE Infocom , 2009. [16] W. Zhao and M. H. Ammar. A message ferrying ap- proach for data delivery in sparse mobile ad hoc net- works. ACM Mobihoc , 2004. [5] S. Dela¨ et, B. Ducourthial, and S. Tixeuil. Self- Stabilizing Systems , chapter Self-stabilization with r- Operators Revisited, pages 68–80. Springer, 2005. [4] E. Daly and M. Haahr. Social network analysis for routing in disconnected delay-tolerant MANETs. In Proc. ACM MobiHoc , 2007. 7 [2] V. Borrel, M. H. Ammar, and E. W. Zegura. Un- derstanding the wireless and mobile network space: a routing-centered classification. In Proc. ACM CHANTS , 2007. [3] J. Burgess, B. Gallagher, D. Jensen, and B. N. Levine. MaxProp: Routing for Vehicle-Based Disruption- Tolerant Networks. In Proc. IEEE Infocom , 2006. [1] CRAWDAD: A community resource for archiving wirelessdata at dartmouth. http://crawdad.cs.dartmouth.edu . http://www.youtube.com/watch?v=kdkCx1xlMkI . [15] J. Whitbeck. Animation of rollernet connectivity graph.