P ROACTIVE S ELECTIVE N EIGHBOR C ACHING FOR E NHANCING M OBILITY S UPPORT IN I NFORMATION -C ENTRIC N ETWORKS Xenofon Vasilakos - Ph.D. Student at AUEB, MMLab member X. Vasilakos, V.A. Siris, G.C. Polyzos and M. Pomonis,

Reduce delay experienced after handing off to another location Mobile Users (MUs) in an ICN architecture Running applications with strict delay requirements 17/8/2012

Domain A Receiver-Driven model in ICN 3 Domain B Publisher ICN architecture MU just re-subscribes after completing the handoff

ICN is mobile-ready What about delay after handoff? – Resend request, wait for resolution and path formation – Wait to get data from (another?) publisher Delay-sensitive applications: – Realtime/emergency notifications, – Teleconferencing, online gaming, etc.. Sensitive to delay jittering – Multimedia Streaming services 17/8/2012Proactive Selective Neighbor Caching4

Proactive Caching SNC: Selective Neighbor Caching Evaluation Future Work and Conclusion 17/8/2012Proactive Selective Neighbor Caching5

Proactive Caching Use proxies – Handle requests – Proactively Cache IOs Neighboring proxies – One hope ahead 6 Proxy: Cache with mobility support mechanisms Proxy: Cache with mobility support mechanisms J: Set of neighbors Publisher

Proactive Caching 7 Proxy: Cache with mobility support mechanisms Proxy: Cache with mobility support mechanisms J: Set of neighbors Publisher Full caching – Proactively fetching and caching requests and IOs to all neighbors Blind approach – Wastes buffer space – Infeasible to cache all IOs for all mobiles – Increases delay for other mobiles

Proactive Caching SNC: Selective Neighbor Caching Evaluation Future Work and Conclusion 17/8/2012Proactive Selective Neighbor Caching8

Selective Neighbor Caching (SNC) 17/8/2012Proactive Selective Neighbor Caching9 SNC selects only an optimal subset of neighbors GOAL: Minimize total costs j j i i S: Subset of neighbor proxies Current Proxy: Mobile User

Selective Neighbor Caching (SNC) 17/8/2012Proactive Selective Neighbor Caching10 a)C hit : Delay cost from a selected proxy j j i i Current Proxy: Mobile User

Selective Neighbor Caching (SNC) 17/8/2012Proactive Selective Neighbor Caching11 a)C hit : Delay cost from a selected proxy b)C miss : Delay cost from a non selected proxy j j i i Current Proxy: Mobile User

Selective Neighbor Caching (SNC) 17/8/2012Proactive Selective Neighbor Caching12 a)C hit : Delay cost from a selected proxy b)C miss : Delay cost from a non selected proxy c)C cache : The cost for allocating buffer space j j i i Current Proxy: Mobile User

Selective Neighbor Caching (SNC) 17/8/2012Proactive Selective Neighbor Caching13 a)C hit : Delay cost for getting IOs from a selected proxy b)C miss : Delay cost in case next proxy was not selected c)C cache : The cost for allocating buffer space d)P ij : The probability for the MU to move from i and attach to j j j i i Current Proxy: Mobile User P ij

What is the optimal subset S* ? 14 Discover which minimizes the total cost:

15 Each Proxy decides autonomously SNC is fully distributed and decentralized Pre-fetching in neighbor j if and only if:

Proactive Caching SNC: Selective Neighbor Caching Evaluation Future Work and Conclusion 17/8/2012Proactive Selective Neighbor Caching16

Simulation Delay gains over Full Caching 17

Simulation delay gains over No Caching 18

Proactive Caching SNC: Selective Neighbor Caching Evaluation Future work and Conclusion 17/8/2012Proactive Selective Neighbor Caching19

Future work Network topology, multiple levels of proxies Traffic demand, IO size, disconnection period The influence of in-network caching Online cache cost evaluation Consider extensions as discussed in the paper 17/8/2012Proactive Selective Neighbor Caching20

Conclusion SNC trades-off delay with cache cost – Selects the appropriate subset of proxies which minimizes cost Simulation investigations quantify cost gains 17/8/2012 Proactive Selective Neighbor Caching for Enhancing Mobility Support in Information- Centric Networks 21

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Analytical Investigations Assume steady state costs and probabilities Illustrate the tradeoff: delay Vs. Ccache – how the tradeoff and gains of SNC depend on cost ratios Cmiss/Chit, Ccache/Chit 17/8/2012Proactive Selective Neighbor Caching23

24  Gain over Full Caching reduces with Cmiss/Chit  Gain over No Caching increases with Cmiss/Chit Full Caching No Caching

25 Gain over full caching increases with Ccache/Chit Gain over no caching reduces with Ccache/Chit Full Caching No Caching

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Defining buffer costs 17/8/2012Proactive Selective Neighbor Caching27

Extensions Identify mobiles of the same type (having a similar mobility behavior) – Consider proxy transition probability for each type When more than one Mus request item k – n k is the average number of requests 17/8/2012Proactive Selective Neighbor Caching28