Content-Based Routing in Mobile Ad Hoc Networks

Milenko Petrovic, Vinod Muthusamy, Hans-Arno Jacobsen

University of Toronto

July 18, 2005

MobiQuitous 2005San 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

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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

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Publish/Subscribe Model

Publisher Publisher

Subscriber Subscriber

Subscriptions

Publications

NotificationNotification

IBM=84

MSFT=27 INTC=19 JNJ=58ORCL=12

HON=24

AMGN=58

Stock marketsNYSE

NASDAQTSX

Subscriptions:IBM > 85ORCL < 10JNJ > 60

BrokerNetwork

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

PublisherSubscriber 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

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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

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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

S1 S2

BS3

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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

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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

1 2 3 4 5 6P S

1 3 4 5

PS1

2 5 6 S2

Difficulties of RAFT-CBR

S3 S1

P

S2

Publication Acknowledgement

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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

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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

40

50

60

70

80

90

100

10 20 30 40 50

Del

iver

y R

atio

(%

)

Subscribers

CBRFT-CBR

RAFT-CBR 0

0.2

0.4

0.6

0.8

1

10 20 30 40 50

Del

ay (s

)

Subscribers

CBRFT-CBR

RAFT-CBR

0

10000

20000

30000

40000

50000

60000

70000

80000

10 20 30 40 50M

essa

ges

Subscribers

RoutingControl

SubscriptionsDataCBR

FT-CBRRAFT-CBR

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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

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

10 20 30 40 50

Del

ay (s)

Subscribers

CBR CBR w/ MC

CBR w/o covering 40

50

60

70

80

90

100

10 20 30 40 50

Deliv

ery

Rat

io (%

)

Subscribers

CBR CBR w/ MC

CBR w/o covering

0

5000

10000

15000

20000

25000

30000

35000

40000

10 20 30 40 50M

essa

ges

Subscribers

RoutingControl

SubscriptionsDataCBR

CBR w/ MCCBR w/o covering

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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

40

50

60

70

80

90

100

0 25 50 75 100

Del

iver

y R

atio

(%

)

Interest Locality (%)

CBR CBR w/ MC

CBR w/o covering

0

0.01

0.02

0.03

0.04

0.05

0.06

0 25 50 75 100

Del

ay (s)

Interest Locality (%)

CBR CBR w/ MC

CBR w/o covering 0

5000

10000

15000

20000

25000

30000

35000

40000

0 25 50 75 100M

essa

ges

Interest Locality (%)

RoutingControl

SubscriptionsDataCBR

CBR w/ MCCBR w/o covering

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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

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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

www.msrg.utoronto.ca