Content-Based Routing in Mobile Ad Hoc Networks Milenko Petrovic, Vinod Muthusamy, Hans-Arno Jacobsen University of Toronto July 18, 2005 MobiQuitous 2005 San Diego, CA

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 2 Mobile Ad Hoc Networks Mobile Ad Hoc Network  Autonomous system of wireless mobile routers  Characteristics Varying bandwidth, latency, connectivity Mobile nodes, and highly dynamic topology Applications  Interactive games, location based advertising, mobile auctions, financial services, selective information dissemination Communication primitives  Unicast  Broadcast  Multicast

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 3 Content Based Routing in MANET Content Based Routing (a.k.a. publish/subscribe)  Unicast, multicast, broadcast  No addresses  loose coupling  Supports large number of fine-grained groups Expressive group membership Applications  Stock updates  Mobile games  Accident information dissemination

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 4 Agenda Background: Publish/Subscribe  Model  Wired distributed algorithm  Benefits Content-Based Routing  Protocols  Evaluation Conclusions

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 5 Publish/Subscribe Model Publisher Subscriber Subscriptions Publications Notification IBM=84 MSFT=27 INTC=19 JNJ=58 ORCL=12 HON=24 AMGN=58 Stock markets NYSE NASDAQ TSX Subscriptions: IBM > 85 ORCL < 10 JNJ > 60 Broker Network

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 6 Distributed Publish/Subscribe Advertisements flooded  Create ad tree Subscriptions propagate along reverse ad path  Create multicast tree Publications propagate along reverse sub path Publisher Subscriber...  Advertisements  Subscriptions  Publications

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 7 Publish/Subscribe Benefits Simple interface Decoupling of producers and consumers of data  Address Content-based routing Anonymity  Platform  Space  Time  Representation (semantic) Efficient data dissemination (scalability)  Push model  Multicast

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 8 Content Based Routing in MANET Challenges  Highly dynamic network  Fault tolerance, reliability CBR (Content-Based Routing)  Based on wired pub/sub protocols FT-CBR (Fault-Tolerant CBR)  Adapt to node mobility RAFT-CBR (Reliable And Fault-Tolerant CBR)  Guaranteed delivery

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 9 CBR Protocol Based on distributed pub/sub protocols  Broadcast ads Build connectivity graph  Unicast subs Setup multicast route Soft state  Beacon ads and subs  Passive route repairs P S  Advertisements  Subscriptions  Publications

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 10 Protocol Optimizations Covering optimization  Common in pub/sub systems  Quench subsumed subscriptions Most Covering (MC) optimization  Forward subscription toward existing multicast tree  Tradeoff route length for transmission and storage  Builds more stable multicast trees P  Subscriptions S1S1 S2S2 BS3S3

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 11 FT-CBR Protocol Routes broken due to node mobility Hop by hop reliability Proactive route repairs  Hop by hop ACK of messages  On unack’d message Expanding ring search to find destination node P S  Publication  Acknowledgement

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 12 RAFT-CBR Protocol End to end reliability  Difficult to ensure in CBR No ad or sub state maintained  Reuse underlying unicast routing protocol Assume publisher is reliable and knows subscriber set  Include (dest, seq) pair in each publication Subscribers send cumulative ACKs and selective NACKs Hierarchical ACK propagation PS 1345 P S1S1 256 S2S2 Difficulties of RAFT-CBR S3S3 S1S1 P S2S2  Publication  Acknowledgement

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 13 Evaluation Simulation Environment  ns-2 network simulator  Implemented CBR protocols Shopping district scenario  Vendors advertise to shoppers in a shopping district  Shoppers interested in nearby stores Parameters  50 mobile nodes (subscribers)  Stationary publisher Random publications Metrics  Delivery ratio  Delivery delay  Message load

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 14 Subscriber Scalability Delivery ratio  75% for CBR, ~100% for FT-CBR Delivery delay  Little change Little change in multicast tree depth No recovery mechanisms (CBR) Message cost  FT-CBR high due to expanding ring search

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 15 Effects of Optimizations Covering and most-covering (MC) optimizations MC improves delivery by 10% points …  Benefits increase with more subscribers... but increases delay and message load  Costs diminish with larger multicast trees Covering significantly reduces message load

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 16 Interest Locality Vary number of subscribers with static interest  Leads to less stable and larger multicast trees MC optimization has largest impact  Makes more stable (but longer) multicast trees

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 17 Related Work Little research into fully content-based pub/sub protocols in MANET Wired CBR protocols  Typically assume stable acyclic topologies Multicast in MANET  MAODV, DVMRP, ODMRP  Group-based (not content-based) Reliability protocols not applicable to content-based

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 18 Conclusions Publish/Subscribe content based routing  Appropriate for mobile networks No “best” protocol  CBR: Low delay, message cost Streaming media applications  FT-CBR: Adapts to dynamic environments High mobility applications  RAFT-CBR: Reliable Financial applications Future work  More protocols Combine best of existing protocols  More experiments Mobile subscribers, realistic scenarios, etc.

July 18, 2005 (MobiQuitous ’05) Content-Based Routing in MANET 19 Content-Based Routing in Mobile Ad Hoc Networks Q&A