Mesh Networking Victor Bahl Senior Researcher Systems and Networking Group Microsoft Research.
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Transcript of Mesh Networking Victor Bahl Senior Researcher Systems and Networking Group Microsoft Research.
Mesh NetworkingMesh Networkinghttp://research.microsoft.com/meshhttp://research.microsoft.com/mesh
Victor BahlVictor BahlSenior ResearcherSenior ResearcherSystems and Networking GroupSystems and Networking GroupMicrosoft ResearchMicrosoft Research
Team IntroductionTeam Introduction
Executive SponsorExecutive SponsorCraig Mundie, CTO & Senior Vice President MicrosoftCraig Mundie, CTO & Senior Vice President Microsoft
Microsoft ResearchMicrosoft ResearchVictor Bahl (Project Lead), Richard Draves, Jitu Padhye, Victor Bahl (Project Lead), Richard Draves, Jitu Padhye, Lili Qiu, Alec Wolman, Brian ZillLili Qiu, Alec Wolman, Brian Zill
The Venice IncubationThe Venice IncubationJeff Erwin (Project Lead), Pierre De Vries, Ian Ferrell, Jeff Erwin (Project Lead), Pierre De Vries, Ian Ferrell, Jason Ginchereau, Steve Kelly, Alexander Popoff, KarenJason Ginchereau, Steve Kelly, Alexander Popoff, Karen
Community NetworkCommunity Network
Community Network Community Network ApplicationsApplications
Internet use increased social contact, public participation and Internet use increased social contact, public participation and size of social network. (social capitalsize of social network. (social capital - access to people, - access to people, information and resources)information and resources)
Keith N. Hampton, MIT (author of “Netville Keith N. Hampton, MIT (author of “Netville Neighborhood Study”)Neighborhood Study”)
URL:URL: http://www.asanet.org/media/neville.htmlhttp://www.asanet.org/media/neville.html
Shared Broadband Internet AccessShared Broadband Internet AccessNeighborhood watchdog (e.g. video Neighborhood watchdog (e.g. video surveillance)surveillance)Neighborhood TiVONeighborhood TiVOMedical & emergency responseMedical & emergency responseDistributed backupDistributed backupNeighborhood eBay, portalsNeighborhood eBay, portals
Bits produced locally, gets used locallyBits produced locally, gets used locallySocial interactionSocial interaction
Mesh Formation: Problem Mesh Formation: Problem FormulationFormulationQuestionQuestion
How many homes in How many homes in the neighborhood have the neighborhood have to sign up before a to sign up before a viable mesh forms?viable mesh forms?
Answer depends onAnswer depends onDefinition of “viable”Definition of “viable”Wireless rangeWireless rangeNeighborhood topologyNeighborhood topologyProbability of Probability of participation by a given participation by a given housholdhoushold
Example ScenarioExample ScenarioViable mesh:Viable mesh: group of at least group of at least
25 houses that form a 25 houses that form a connected graphconnected graph
TopologyTopology: A North Seattle : A North Seattle Neighborhood. 8214 Neighborhood. 8214 houses, 4Km x 4Kmhouses, 4Km x 4Km
Wireless rangeWireless range: 50, 100, 200 : 50, 100, 200 and 1000 metersand 1000 meters
Houses decide to Houses decide to join at join at randomrandom, independent of , independent of each other. We consider each other. We consider 0.1% to 10% participation 0.1% to 10% participation rates.rates.
Mesh FormationMesh Formation
Increasing range is key for good mesh connectivity
5-10% subscription rate 5-10% subscription rate needed for suburban needed for suburban topologies with topologies with documented wireless documented wireless rangesranges
Once a mesh forms, it is Once a mesh forms, it is usually well-connected usually well-connected
i.e. number of outliers are i.e. number of outliers are few (most nodes have > 2 few (most nodes have > 2 neighbors)neighbors)
Need to investigate other Need to investigate other joining modelsjoining models
Business model Business model considerations will be considerations will be importantimportant
SuburbiaSuburbiaUpper-middle class Upper-middle class neighbourhoodneighbourhood
Houses about 40-120’ Houses about 40-120’ apartapart
21 houses covering 7.8 21 houses covering 7.8 acres or ~1/3 acre lotsacres or ~1/3 acre lots
Microwave ovens, Microwave ovens, cordless phones, cordless phones, televisions etc. cause televisions etc. cause interferenceinterference
Angled sheetrock and Angled sheetrock and concrete walls, hills concrete walls, hills and trees absorb signal and trees absorb signal and create multi-path and create multi-path reflectionsreflections
Not a pleasant place to Not a pleasant place to roll out wirelessroll out wireless
One reason why One reason why cellular uses 80’-100’ cellular uses 80’-100’ masts for their cell masts for their cell towerstowers
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40
60
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0
5 GHz:5 GHz:Bandwidth is good, Bandwidth is good, provided you can get a provided you can get a mesh to formmesh to form
Published 802.11a Published 802.11a ranges led us to believe ranges led us to believe we could achieve the we could achieve the yellow circleyellow circle
Measured range from Measured range from the apartment trial is the apartment trial is the red circlethe red circle
Range is not sufficient Range is not sufficient to bootstrap mesh until to bootstrap mesh until installed % is quite high installed % is quite high (in this diagram ~50%)(in this diagram ~50%)
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802.11a in a Multihop 802.11a in a Multihop NetworkNetworkImpact of path length on TCP Throughput
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4000
6000
8000
10000
12000
0 1 2 3 4 5 6 7
Path Length (Hops)
TC
P T
hro
ug
hp
ut
(Kb
ps)
Round Trip Delay versus Round Trip Delay versus Node Density Node Density
Average RTTavg_rtt = 0.1*curr_sample + 0.9*avg_rtt
One sample every 0.5 seconds
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0 20 40 60 80 100 120 140 160 180
Time
Ave
rag
e R
TT
A new 100Kbps CBR connection starts every 10 seconds, between a new pair of nodes. All nodes hear each other.
Collision between ISM Collision between ISM devicesdevices
Panasonic 2.4GHz Spread Spectrum Phone 5m and 1 Wall from receiver
Phone
Colliding standardsColliding standards
Performance worsens when there are large number of short-range radios in the vicinity
Courtesy: Mobilian Corp.
To make it realTo make it realIdentify and solve key problems Identify and solve key problems
build and deploy a mesh build and deploy a mesh prototypeprototype
Conclusion Conclusion Meshes are viable Meshes are viable
existing technologies are existing technologies are inadequateinadequate
Problem SpaceProblem SpaceRange and Capacity Range and Capacity [Talk by Jim K; Poster by John D. & Ranveer [Talk by Jim K; Poster by John D. & Ranveer
C.]C.]Electronically steerable directional antenna or MIMO for range enhancementElectronically steerable directional antenna or MIMO for range enhancementMultiple frequency meshesMultiple frequency meshesMulti-radio hardware for capacity enhancement via greater spectrum Multi-radio hardware for capacity enhancement via greater spectrum utilizationutilizationNew data channel MAC for higher throughputNew data channel MAC for higher throughputTools for predicting & analyzing network viability & performanceTools for predicting & analyzing network viability & performance
Multihop Routing Multihop Routing [Talk by Rich D.; Poster & Demo by Jitu P. & [Talk by Rich D.; Poster & Demo by Jitu P. & Brian Z.]Brian Z.]
L2.5 on-demand source routing. Routes selected based on link quality L2.5 on-demand source routing. Routes selected based on link quality Route selection with multiple radiosRoute selection with multiple radios
Security and FairnessSecurity and FairnessGuard against malicious users (and freeloaders)Guard against malicious users (and freeloaders)EAP-TLS between MeshBoxes, PEAPv2 or EAP-TLS between clients and EAP-TLS between MeshBoxes, PEAPv2 or EAP-TLS between clients and MeshBoxesMeshBoxesPriority based admission control, Secure traceroute Priority based admission control, Secure traceroute
Self Management & Self Healing Self Management & Self Healing [Talk by Lili Q.; Poster by AP][Talk by Lili Q.; Poster by AP]Desirable: avoid network operator - minimal human intervention Desirable: avoid network operator - minimal human intervention Watchdog mechanismWatchdog mechanismData cleaning and liar detectionData cleaning and liar detectionOnline simulation based fault isolation and diagnosisOnline simulation based fault isolation and diagnosis
Smart Spectrum UtilizationSmart Spectrum Utilization Spectrum EtiquittesSpectrum EtiquittesAgile Radios, cognitive radiosAgile Radios, cognitive radiosCognitive software & applicationsCognitive software & applications
Analytical TechniquesAnalytical TechniquesInformation theoretic tools that predict expected capacity with practical Information theoretic tools that predict expected capacity with practical constraints, based on experimental dataconstraints, based on experimental data
Digital Rights Management (DRM)Digital Rights Management (DRM)Broadband access will become popular with expanded digital content.Broadband access will become popular with expanded digital content.Increase the value proposition for end-users/subscribersIncrease the value proposition for end-users/subscribers
Ease of use (Plug and play, HCI)Ease of use (Plug and play, HCI)Make the user experience pleasant Make the user experience pleasant QoS protocols over wireless meshes to improve content deliveryQoS protocols over wireless meshes to improve content delivery
Problem Space (Cont)Problem Space (Cont)
Proof of Concept via rapid prototyping and testbed deployments
End Device
Scenario: Neighborhood Wireless MeshesInternet
Gas Station
Bus Stop
Mesh Router 2
End Device (Guest to Router 1)
Mesh Router 1
Mesh End Device
EXIT
Any StreetMesh Zone
Mesh Router 3
(Internet TAP)
Mesh Router 5
Mesh Router 7
90
101
206
Mesh Router
End DeviceEnd DeviceConnectsConnects to a Mesh to a Mesh RouterRouterStandards CompliantStandards Compliant Network InterfaceNetwork Interface
Mesh Router / MeshBoxMesh Router / MeshBoxRoutes trafficRoutes traffic within the within the mesh and to the mesh and to the neighborhood Internet neighborhood Internet GatewayGatewayServes as Serves as access pointaccess point for End Devicesfor End Devices
Neighborhood Internet Neighborhood Internet GatewayGateway
GatewayGateway between the between the mesh nodes and the mesh nodes and the InternetInternet
ITAP
Data Channel RadioMiniport Driver
Control Channel Radio
Miniport driver
Mesh Routing Functionality
Mesh Management Module
TCP / IP
Mesh Connectivity Layer(MCL)
Multi-hop Routing/Bridging Radio Selection Metric
Topology Control
Link Monitor Module
Mesh Box Configuration
SECURITY
Diagnostics Kernel Module
Diagnostics Client and Server DLLs
Research ResultsResearch ResultsSpectrum EtiquetteSpectrum Etiquette
P. Bahl, A. Hassan, P. Vries, P. Bahl, A. Hassan, P. Vries, Spectrum Etiquettes for Short Spectrum Etiquettes for Short Range Wireless Devices Operating in the Unlicensed Range Wireless Devices Operating in the Unlicensed Band - A ProposalBand - A Proposal,,,,White paper, Spectrum White paper, Spectrum Policy: Property or Commons, Stanford Law School
Multi Radio MeshesMulti Radio MeshesA. Adya, P. Bahl, J. Padhye, A. Wolman, and L. Zhou. A. Adya, P. Bahl, J. Padhye, A. Wolman, and L. Zhou. A Multi-Radio Unification Protocol for IEEE 802.11 Wireless Networks. BroadNets 2004 (also Technical Report, MSR-TR-. BroadNets 2004 (also Technical Report, MSR-TR-2003-41, June 2003)2003-41, June 2003)
Determining Mesh CapacityDetermining Mesh Capacity
K. Jain, J. Padhye, V. Padmanabhan, and L. Qiu. K. Jain, J. Padhye, V. Padmanabhan, and L. Qiu. Impact of Interference on Multi-hop Wireless Network Performance. ACM Mobicom, San Diego, CA, September 2003 ACM Mobicom, San Diego, CA, September 2003
Mesh Self ManagementMesh Self ManagementL. Qiu, P. Bahl, A. Rao, and L. Zhou. L. Qiu, P. Bahl, A. Rao, and L. Zhou. Fault Detection, Isolation, and Diagnosis in Multi-hop Wireless Networks. Technical Report, MSR-TR-2004-11, December 2003Technical Report, MSR-TR-2004-11, December 2003
Research Results (cont.)Research Results (cont.)
Single Radio Mesh PerformanceSingle Radio Mesh PerformanceR. Draves, J. Padhye, and B. Zill. R. Draves, J. Padhye, and B. Zill. Comparison of Comparison of Routing Metrics for Static Multi-Hop Wireless Routing Metrics for Static Multi-Hop Wireless NetworksNetworks.. ACM SIGCOMM 2004 (also Technical Report, ACM SIGCOMM 2004 (also Technical Report, MSR-TR-2004-18, March 2004)MSR-TR-2004-18, March 2004)
Single Radio Mesh PerformanceSingle Radio Mesh PerformanceR. Draves, J. Padhye, and B. Zill. R. Draves, J. Padhye, and B. Zill. Routing in Multi-radio, Routing in Multi-radio, Multi-hop Wireless Mesh Networks,Multi-hop Wireless Mesh Networks, To appear in ACM To appear in ACM MobiCom 2004MobiCom 2004
Multi Radio Mesh Routing & Multi Radio Mesh Routing & PerformancePerformance
L. Qiu, P. Bahl, A. Rao, and L. Zhou. L. Qiu, P. Bahl, A. Rao, and L. Zhou. Fault Detection, Isolation, and Diagnosis in Multi-hop Wireless Networks. Technical Report, MSR-TR-2004-11, Technical Report, MSR-TR-2004-11, December 2003December 2003
Capacity EnhancementCapacity EnhancementProblemProblem
Improve throughput via better utilization of the spectrumImprove throughput via better utilization of the spectrum
Design ConstraintsDesign ConstraintsRequire only a single radio per nodeRequire only a single radio per nodeUse unmodified IEEE 802.11 protocolUse unmodified IEEE 802.11 protocolDo not depend on existence of control channelDo not depend on existence of control channel
Assumption Assumption Node is equipped with an omni-direction antenna Node is equipped with an omni-direction antenna
- - MIMO technology is OKMIMO technology is OK Multiple orthogonal channels are availableMultiple orthogonal channels are availableChannel switching time is 80 usecs. Channel switching time is 80 usecs.
- - current speeds 150 microsecondscurrent speeds 150 microseconds
Capacity EnhancementCapacity Enhancement
1
2
5
4 6
3
Only one of 3 pairs is active @ any given time
In current IEEE 802.11 meshes
10 msecs 10 msecs 10 msecs
1 2
3 4
1 4
5 2
Ch 1
Ch 2
…5 6 3 6Ch 3
5 4
1 6
3 2
With MSR’s SSCH enabled meshes
PerformancePerformance
0
0.5
1
1.5
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3.5
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10 20 30 40 50
Number of FlowsT
hro
ug
hp
ut
(Mb
ps)
SSCH M802.11
Significant capacity improvement when traffic load is on multiple separate flows
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10 20 30 40 50
Number of Flows
Th
rou
gh
pu
t (M
bp
s)
SSCH IEEE 802.11
100 nodes, IEEE 802.11a, 13 channels, every flow is multihop
Avg. per node Throughput Total System Throughput
Mesh Diagnosis Mesh Diagnosis Visualization ModuleVisualization Module
TestbedsTestbedsDetails
23 to 30 nodes23 to 30 nodesInexpensive desktops (HP d530 Inexpensive desktops (HP d530 SF)SF)Two radios in each nodeTwo radios in each node
NetGear WAG or WAB, Proxim NetGear WAG or WAB, Proxim OriNOCOOriNOCOCards can operate in a, b or g Cards can operate in a, b or g mode.mode.
PurposeVerification of the mesh software Verification of the mesh software stackstack
Routing protocol behaviorRouting protocol behaviorFault diagnosis and mesh Fault diagnosis and mesh management algorithmsmanagement algorithmsSecurity and privacy architecture Security and privacy architecture Range and robustness @ 5 GHz Range and robustness @ 5 GHz with different 802.11a hardwarewith different 802.11a hardware
Stress TestingVarious methods of loading testbed:Various methods of loading testbed:
Harpoon traffic generator Harpoon traffic generator (University of Wisconsin) (University of Wisconsin)
Peer Metric traffic generator Peer Metric traffic generator Ad-hoc use by researchers Ad-hoc use by researchers
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Appro
x. 6
1 m
Approx. 32 m
Redmond Apartment TrialsRedmond Apartment Trials
Microsoft Campus
32 Bellaire Apts
31
Deployed by The Venice Team
UNIT FF UNIT GG
Road
UNIT HH20 Feet
ControlAptGG302
Road
Parking Lot
FF203
UNIT CC
UNIT BB
Carport
BB103
BB302
BB201
ControlAptGG302
GG202
HH301
B
B
B
B
B
B
B
B
A
A
bb
a
a
= MeshBox
A B
B
A
FF102
B
A
A
A
A
Redmond Apartment TrialRedmond Apartment Trial
Control Apt GG302 Mesh Box
Mesh Hall (Kitchen)
Apt FF201
Cambridge UK TrialCambridge UK Trial
MSR-Cambridge - 1st Floor, Mesh box Locations
UK3-GtwyUK8
UKMCE20
UK2
UK6UK1UK-MCE20 is the
Kiosk with posters.
= Mesh Box location = Mesh Box location
10 node meshWorking with ehome to create a media sharing demo in collaboration with ZCast DVB trial
Deployed by The Venice Team
Near Term GoalsNear Term Goals
Multi-radio mesh routersMulti-radio mesh routers
Directional Antenna enabled meshesDirectional Antenna enabled meshes
Multi spectral meshesMulti spectral meshes
Mesh Connectivity LayerMesh Connectivity Layer
Self Managing MeshesSelf Managing Meshes
Large Scale TestbedsLarge Scale Testbeds
We hope to take this research to the Point of IrrefutabilityWe hope to take this research to the Point of Irrefutability
Thanks!Thanks!
http://research.microsoft.com/meshhttp://research.microsoft.com/mesh
SSCH Algorithm & SSCH Algorithm & PerformancePerformanceEvery node has a channel hopping scheduleEvery node has a channel hopping schedule
4 pairs of (channel, seed) = (4 pairs of (channel, seed) = (xxii, a, aii))
Hop to a new channel every 35 packets, 1536 bytes/packetHop to a new channel every 35 packets, 1536 bytes/packetxxii ( (xxii + a + aii) mod 13) mod 13 (802.11a has 13 channels)(802.11a has 13 channels)
Parity slot Parity slot xxparityparity = a = a1 1 prevents logical partitioning prevents logical partitioning When unsynchronized, still overlap ~1/13When unsynchronized, still overlap ~1/13thth of time of time can can exchange updated schedulesexchange updated schedules
Synchronize = Change your schedule to match another node’sSynchronize = Change your schedule to match another node’s
Common case in sending is know recipient node’s scheduleCommon case in sending is know recipient node’s schedulepropagation of schedule information is more frequent than propagation of schedule information is more frequent than start of new flowsstart of new flowsif wrong, pay latency penaltyif wrong, pay latency penalty
Mesh Security Mesh Security ArchitectureArchitecturePhilosophyPhilosophy
Mesh is open to all, however, Mesh is open to all, however, people who contribute people who contribute resources to the mesh get resources to the mesh get priority.priority.
Design GoalsDesign Goals
Guard against faulty or Guard against faulty or hacked Mesh Boxeshacked Mesh Boxes
Defend against disruption Defend against disruption (e.g., denial-of-service (e.g., denial-of-service attacks) by malicious End attacks) by malicious End DevicesDevices
Protect mesh traffic privacyProtect mesh traffic privacy
Protect access to network Protect access to network resourcesresources
AssumptionsAssumptions
Difficult to hack into a Mesh Difficult to hack into a Mesh Box (similar to cable Box (similar to cable modems)modems)
End Device
Server
End Device
Laptop
Internet
Certificate
Certificate
Certificate
Internet Gateway
Compromised Mesh Box
Malicious End Device
NeighborhoodFile Server
Snooper
Regulations handle malicious RF Interference attacks
Basic FrameworkBasic FrameworkCertificationCertification
Mesh Routers have Mesh Routers have built-built-in public-key certificatesin public-key certificates for authenticating to each for authenticating to each otherother
Mesh Router owners use Mesh Router owners use them to them to issue certificatesissue certificates to End Devicesto End Devices
Mesh Box accepts Mesh Box accepts certificates issued by any certificates issued by any Mesh Box within rangeMesh Box within range
Access to resources is Access to resources is controlled based on policy controlled based on policy and End Device certificateand End Device certificate
Encryption & AnonymityEncryption & Anonymity
Traffic between Mesh Boxes Traffic between Mesh Boxes is encryptedis encrypted to foil to foil eavesdropperseavesdroppers
Misbehaving Mesh Boxes Misbehaving Mesh Boxes have their certificates have their certificates ““blackballedblackballed””
Traffic from uncertified End Traffic from uncertified End Devices Devices is preventedis prevented from from disrupting certified trafficdisrupting certified traffic