p roactive s elective n eighbor c aching for e nhancing m obility s upport in i nformation -c entric...

PROACTIVE SELECTIVE NEIGHBOR CACHINGFOR ENHANCING MOBILITY SUPPORT IN INFORMATION-CENTRIC NETWORKS

Xenofon Vasilakos - xvas@aueb.grPh.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

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Domain B

Publisher

PublisherICN 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

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• Proactive Caching• SNC: Selective Neighbor Caching• Evaluation• Future Work and Conclusion

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Proactive Caching

• Use proxies– Handle requests– Proactively Cache IOs

• Neighboring proxies– One hope ahead

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Proxy: Cache with mobility support mechanisms

Proxy: Cache with mobility support mechanisms

J: Set of neighbors

Publisher

Proactive Caching

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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

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Selective Neighbor Caching (SNC)

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• SNC selects only an optimal subset of neighbors

• GOAL: Minimize total costsjj

iiS: Subset of

neighbor proxies

Current Proxy:

Mobile User

Selective Neighbor Caching (SNC)

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a) Chit: Delay cost from a selected proxy

jj

iiCurrent Proxy:

Mobile User

Selective Neighbor Caching (SNC)

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a) Chit: Delay cost from a selected proxy

b) Cmiss: Delay cost from a non selected proxy

jj

iiCurrent Proxy:

Mobile User

Selective Neighbor Caching (SNC)

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a) Chit: Delay cost from a selected proxy

b) Cmiss: Delay cost from a non selected proxy

c) Ccache: The cost for allocating buffer space jj

iiCurrent Proxy:

Mobile User

Selective Neighbor Caching (SNC)

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a) Chit: Delay cost for getting IOs from a selected proxy

b) Cmiss: Delay cost in case next proxy was not selected

c) Ccache: The cost for allocating buffer space

d) Pij: The probability for the MU to move from i and attach to j

jj

iiCurrent Proxy:

Mobile User

Pij

What is the optimal subset S* ?

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Discover which minimizes the total cost:

cachemisshithithit CSNCSPCSP )())(1()(

JS

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Each Proxy decides autonomously

• SNC is fully distributed and decentralized

Pre-fetching in neighbor j if and only if:

hitmiss

cacheij CC

Cp

• Proactive Caching• SNC: Selective Neighbor Caching• Evaluation• Future Work and Conclusion

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Simulation Delay gains over Full Caching

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Simulation delay gains over No Caching

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• Proactive Caching• SNC: Selective Neighbor Caching• Evaluation• Future work and Conclusion

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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

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Conclusion

• SNC trades-off delay with cache cost– Selects the appropriate subset of proxies which

minimizes cost

• Simulation investigations quantify cost gains

17/8/2012Proactive Selective Neighbor Caching for

Enhancing Mobility Support in Information-Centric Networks

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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

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

Full Caching

No Caching

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• 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

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Extensions

• Identify mobiles of the same type (having a similar mobility behavior)– Consider proxy transition probability for each type

• When more than one Musrequest item k– nk is the average number

of requests

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