Distributed Dataset Synchronization in Named Data NetworkingDistributed Dataset Synchronization in Named Data Networking Wentao Shang Final defense 06/01/2017 1

DistributedDatasetSynchronizationin

NamedDataNetworkingWentaoShangFinaldefense06/01/2017

1

ResearchProblem

• Distributedapplicationsrequireefficientsupportformulti-partycommunication• Multiplenodespublishandsharedata

• NamedDataNetworking(NDN)enablesnewwaystosupportmulti-partycommunicationthroughdatasetsynchronization(sync)• Leveragingdata-centricnetworkarchitecture• Withoutcentralizedserver

2

StateofAffairs

• AnumberofsyncprotocolshavebeendevelopedsincethestartoftheNDNproject• CCNx 0.8Sync;ChronoSync;iSync;CCNx 1.0Sync;RoundSync;pSync

• AnumberofexistingNDNapplicationsrunontopofsync• CCNx repo:replicateddatastorage• ChronoShare:distributedfilesharing• ChronoChat:server-lessgroupchat• NLSR:link-stateroutingprotocol• NDN-RTC:groupconferencing• Distributeddatacatalog• IoT pub-subsystem

3

ResearchObjectives

• UnderstandingthedesignspaceofNDNsync• SystematicexaminationofalltheexistingNDNsyncprotocols

• Designinganewsyncprotocol• Learningfromthedesigntradeoffsintheexistingprotocols• Supportingnewfunctionsnotofferedbytheexistingworks• Applyingmethodsdevelopedinthedistributedsystemsarea

4

NDNOverview

• Uniqueandsecuredbindingbetweennameandcontent• Namedata,andsecuredatadirectly

• Name-baseddataretrieval• Stateful Interest-Dataexchange• Secureddataenablesin-networkstorage

5

/ucla/cs/wentao

Fetch:/ucla/cs/wentao/slides/v5

Interest

Data

/ucla/cs/wentao/slides/v5

InterestFetch:/ucla/cs/wentao/slides/v5

NDNSyncforMulti-PartyCommunication

• Enableagroupofnodestopublishandconsumedatainashareddataset• Maintainaconsistentstateofthedatasetamongtheparticipants

• NDNprovidesuniquebindingbetweennameanddataàSynchronizingdataset=synchronizingthenamespaceofthedataset

• FullyutilizeNDN’sdata-centriccommunication• In-networkcaching• Multicastdatadelivery

6

SyncinNDN

7

NationalParkTouristA

TouristB

TouristC

…/road/X/hazard/road/Y/closed

Bulletinboard…

/road/X/hazard/road/Y/closed

Bulletinboard


Bulletinboard

SyncinNDN

8

NationalPark

Publishalertdata:“BearspottedatsiteZ”

TouristA

TouristB


Bulletinboard

TouristC


Bulletinboard

SyncinNDN

9


TouristB

…/road/X/hazard/road/Y/closed/site/Z/bear

Bulletinboard

Synchronize


Bulletinboard

TouristC


Bulletinboard

SyncinNDN

10


TouristB


Bulletinboard …/road/X/hazard/road/Y/closed/site/Z/bear

Bulletinboard

TouristC


Bulletinboard

SyncinNDN

11


TouristB


Bulletinboard …/road/X/hazard/road/Y/closed/site/Z/bear

Bulletinboard

TouristC


Bulletinboard

ComparingNDNSyncwithToday’sDataSynchronizationSolutions• TraditionalSynchronizationwithTCP/IPnetworking• Networkprovidespoint-to-pointcommunication• Datasetsynchronizationachievedattheapplicationlayer

• SyncinNDN• Networkprovidesdata-centriccommunication• Syncprotocolprovidesdatatransportservicefortheapplication• Becauseofdata-centricnature,NDNsyncdoesnotrequireallpartiesconnectedtoeachotherallthetime

12

Dataset

DesignSpaceofNDNSyncProtocols

13

CommonSyncProtocolFramework

14

/road/X/hazard/road/Y/closed/site/Z/bear

Summary

DatasetnamespaceGenerateaconcisesummaryofthedatasetnamespacetobecommunicatedbetweennodes

Update

Detectandreconcileinconsistencybyexchangingthesummaryperiodically

(Optionally)supportquicknotificationtoothernodeswhenpublishingnewdata

Summary

Summary

Summary

KeyDesignAspects

• Datasetnaming• Howtonamedataitemsintheshareddataset

• Namespacerepresentation• Howtoprovideanefficientsummaryofnamespace

• Statesynchronizationmechanism• HowtomakenodeslearnaboutchangesASAP• Howtodetectandreconcileinconsistencycausedbyvariousfactors

15

DesignChoicesinDatasetNaming

• Syncprotocolsynchronizesapplicationdatanamesdirectly• CCNx 0.8Sync;iSync;CCNx 1.0Sync

• Syncprotocolnamesdatabyeachproducersequentially• Encapsulateapplicationnamesifneeded• ChronoSync;RoundSync;pSync

16


/TouristA/13:{/site/Z/bear}/TouristA/14:{/site/W/alert}/TouristB/55:{/road/X/harzard}/TouristB/56:{/road/Y/closed}

DesignChoicesinNamespaceRepresentation

• Enumeration• Losslesscompressioninthenamespace(ornocompression)• CCNx 1.0Sync

• Hashing• One-waycompressionofnamespace• CCNx Sync;ChronoSync;RoundSync

• InvertibleBloomFilter(IBF)• Storeandextractindividualnamehashes• iSync;pSync

17

DesignChoicesinStateSynchronizationMechanism• Long-livedInterest• NodesmaintainpendingInterestsinthenetworktosolicitchangesfromothers• ChronoSync;pSync;

• Notification-driven• Nodesinformothersaboutnewchanges• CCNx 1.0Sync;RoundSync;

• Periodicexchangeofdatasetsummary• Nodesexchangetheirstatesummaryperiodicallytodetectandreconcileinconsistency• CCNx 0.8Sync;iSync

18

EvolutionofExistingSyncProtocols

19

Useapplicationname Namedatasequentially

Enumeration

Hashing

IBF

Long-livedInterest

Notificationdriven

Enumeration

Hashing

IBF

CCNx 0.8Sync

CCNx 1.0Sync

iSync pSync

W.Shangetal.,“ASurveyofDistributedDatasetSynchronizationinNamedDataNetworking”,NDN-TR-0053,2017

Periodicexchange

Long-livedInterest

Notificationdriven

Periodicexchange

ChronoSyncRoundSync

CCNx 0.8Sync

• Summarizedatasetnamespaceusingcombinedhashesovertreestructure• SendInterestwithroothashperiodicallytorequestdifferenthash(es)• Takemultipleroundstoreconcilethedifferences

20

/

/road /site/Z/bear

/road/X/hazard /road/Y/closed

H3=Hash(/road/X/harzard) H4=Hash(/road/Y/closed)

H1=H3+H4

H2=Hash(/site/Z/bear)

H0=H1+H2RootAdvice Interest:H0’

RootAdvice reply:H0

NodeFetch Interest:H0

NodeFetch reply:H1,H2

NodeFetch Interest:H1

NodeFetch reply:H3,H4

…

iSync:ImprovingCCNx 0.8Sync

• UseInvertibleBloomFilter(IBF)tosummarizethenamespace• DetectdifferencesusingIBFsubtraction

• Reducethesynchronizationround-tripatthecostoflargernamespacerepresentation• ExchangeonlytheIBFdigest• NeedextraRTTtoretrievetheIBFcontent

• BothCCNx 0.8SyncandiSync synchronizeviaperiodicexchangeofstatesummary• Addadditionaldelaytolearningnewdata

21


InvertibleBloomFilter

01de…478a…33fc…

Hash

IBF Digest

Hash

Store Extract

ChronoSync

• Namedatasequentially• Summarizethenamespacewithadigest• Maintainlong-livedInterestinthenetworktowaitfornextupdate• Need“excludefilter”toretrievesimultaneousupdatesbymultipleproducers

• Interestcarriesstatedigestforinconsistencydetection• Providea“recovery”mechanismaslastresortforrepairingstateconflict

22

…/TouristA/12/TouristA/13

…/TouristB/54/ToursitB/55

…/TouristC/29/TouristC/30

{/TouristA:13,/TouristB:55,/TouristC:30}

DigestHash

TouristA

TouristB

TouristC/park/sync/[Digest]

{/TouristB:56}

{/TouristC:31}

X

pSync:Pub-suboverSync

• TakethesequentialnameapproachfromChronoSync,IBFasrepresentationfromiSync• IBFstoresonlyeachnode’slatestseq#,sosizeisdeterminedbythegroupsize

• Eachconsumersendslong-livedInterestwitholdIBFtorequestupdatesfromaproducer• IBFprovidesspecificinformationabouttheconsumer’sstate• Producercanreplywithnewdatanamesdirectly

23

/producer/[BF]/[old-IBF]

/producer/[BF]/[old-IBF]/[new-IBF]{/site/Z/31}

SyncInterest

Reply

/road/X/13 /road/Y/55

Store

InvertibleBloomFilter

ExtractH1 H2 H3

Hash/site/Z/30

OtherSyncProtocols

• CCNx 1.0Sync:anotherfixtoCCNx Sync• Enumeratedatanamesinamanifestfile• Broadcastmanifestdigestwhenpublishingnewdata

• RoundSync:arevisiontoChronoSync• Reducebutnoteliminatethesimultaneouspublishingproblem

24

LessonsLearned

• Allowingsyncprotocoltonamedatasequentiallysimplifiesthedesign• Onlyneedtosynchronizethelatestsequencenumbers

• Notificationsshouldcarryspecificupdateinformation• Sothatrecipientscanfetchnewdatadirectly,withoutfurtherexchangetoidentifythenewdata

• Avoidusinglong-livedInteresttofetchnewupdates• Along-livedInterestcannotfetchmultipledataproducedatthesametime• Long-livedInterestsaddburdentonetworkinmaintainingInterestpathstate

25

VectorSync Protocol

26

SynchronizationwithManagedGroup

• Manydistributedapplicationsrequireexplicitgroupmembershipmanagement• Examples:• ResourcediscoveryinIoT networks• Routingprotocol

• Existingsyncprotocolsdonotsupportmembershipmanagement• Difficulttoremovedepartednodesfromthedatasetstate

27

/Home/Thermostat/Home/AC/Home/Heater/Home/MotionSensor

VectorSync DesignHighlights

• Maintainaconsistentlyorderedlistofgroupparticipants(calledaview)amongallparticipatingnodes• Utilizealeader-drivenprocesstosynchronizetheviewamongallnodes• Leveragesequentialdatasetnamingtosynchronizethedatasetusingversionvector• Adoptnotification-drivensynchronizationwithspecificupdateinfo

28D.Parkeretal.,“DetectionofMutualInconsistencyinDistributedSystems”,1983

VectorSync Overview

29

ApplicationLogic

SharedDataset

DatasetStateStatesynchronization

PublishData

NotifyofRemoteData

NDNNetwork

Dataretrieval

GroupMembershipInfo

Viewsynchronization

SyncNode

VectorSync Overview

30

Statesynchronization

PublishData

NotifyofRemoteData

NDNNetwork

Dataretrieval

Viewsynchronization

DatasetState

GroupMembershipInfo

SyncNode

ApplicationLogic

SharedDataset

DatasetNamespace

• Sequentialdatanaming• Usingsequencenumbers

• Vectorrepresentationofnamespace• Producernamesandorderingspecifiedinthemembershipinfo

31

Statevector

[17,240,153]

Membershipinfo

0:Thermostat1:AC2:MotionSensorNode

order

Shareddataset…

/…/Thermostat/16/…/Thermostat/17

…/…/AC/238/…/AC/239/…/AC/240

…/…/MotionSensor/151/…/MotionSesnor/152/…/MotionSensor/153

Thermostat:17 AC:240 MotionSensor:153

PublishingandSynchronizingData

32

• MulticastnotificationInterestcarriesexplicitinformationaboutchanges• Nodedatacarriesfullstatevectorofthepublisher,providescausalordering

MotionSensor

Thermostat

AC

Publish/…/AC/241 NotificationInterest:/home/bonjour/AC/241

Replywithstatevector

Interest:/…/AC/241

Data:/…/AC/154app message,vector=

[17,240,153]

DetectingandReconcilingInconsistency

33

[17,240,153]

Receivedvector:[18,242,151]

Localvector:

Join

[18,242,153]Updatedvector:

Membershipinfo

0:/…/Thermostat1:/…/AC2:/…/Heater

/…/Heater/152/…/Heater/153Missingdata:

UpdatethelocalvectorwiththeresultofJoinandretrievemissingdata

VectorSync Overview

34

ApplicationLogic

SharedDataset

DatasetStateStatesynchronization

PublishData

NotifyofRemoteData

NDNNetwork

Dataretrieval

GroupMembershipInfo

Viewsynchronization

SyncNode

Soft-stateMembership

• Nodesrefreshtheirmembershipbypublishingdata(inthedataset)• Authenticatedassertionofexistence

• Whenapplicationisidle,nodepublishes“heartbeat”dataperiodically• Enableperiodicexchangeofstatevectors

• Anodeisconsidered“gone”ifnodatareceivedfromitforcertainamountoftime• Heartbeatperiodandtimeoutvaluesdecidedbyapplication

35

Thermostat

AC

MotionSensor

…/…/Thermostat/56appdata/…/Thermostat/57appdata …

/…/MotionSensor/101heartbeat/…/MotionSensor/102appdata

…/…/AC/23appdata/…/AC/24heartbeat

Leader-drivenMembershipManagement

• Nodesselectaleadertomanagethegroup

• Leaderdefinesandpublishesitsviewofthegroup• Othernodesfollowtheleader’sview

• Leadermonitorsthegroupandcreatesnewviewwhenthemembershipchanges

• Viewsarenamedsequentiallyusingviewnumber• Leaderincreasesthenumberwhencreatingnewview

• Uponnetworkpartition,eachpartitionmayselectitsownleaderwhichcreatesitsownview• ViewID=(viewnumber,leadername)

36

0:Thermostat;1:Heater;2:AC;3:MotionSensor

(1,Thermostat)

0:Thermostat; 1:AC;2:MotionSensor

(2,Thermostat)

0:Thermostat1:MotionSensor

(3,Thermostat)0:AC(3,AC)

Selectingaleader

• Ifthecurrentleaderhasleft,theremainingnodescompetetobecomethenextleader viarandomleaderselection• Whenanodedetectsleaderdeparture,itstartsarandomwaittimer• Afterthetimergoesoff,thenodedeclaresitselftheleaderandcreatesanewview• Ifitnoticesanewviewbeforethetimergoesoff,itcancelsthetimerandjointhenewview

• Otherleaderselectionmechanismcanalsobeused• Usingpre-configuredpreferencelist

37

SynchronizingtheView

• Leadersignsandpublishesviewinfoasdatawhencreatingnewview• Name:/[multicast-prefix]/vinfo/[view-id]• Containsnamesandcertificatesofthemembers

• ViewIDcarriedinallnotificationInterests

• Nodefetchestheviewinfoifnoticingalargerviewnumber• Jointhenewviewafterreceivingtheviewinfo

• Nodekeepspublishingdatainitscurrentviewbeforetheviewsynchronizationfinishes

38

0:Thermostat,{cert}1:AC,{cert}2:Heater,{cert}3:MotionSensor,{cert}

Thermostat’skeySign

/home/bonjour/vinfo/(1,Thermostat)

ViewSynchronizationwithSingleLeader

39

View(4,Thermostat):{0:AC;1:MotionSensor;2:Thermostat;3:Heater}

ThermoStat

MotionSensor

Heater

AC

RemoveHeaterPublishviewinfofor

(5,Thermostat)

/home/bonjour/(5,Thermostat)/…



/home/bonjour/vinfo/(5,Thermostat)0:AC,{cert};1:MotionSensor,{cert};

2:Thermostat,{cert}

Moveto(5,Thermostat)

Moveto(5,Thermostat)

UpdatingStateAfterMembershipChange

40

0:AC,{cert}1:MotionSensor,{cert}2:Thermostat,{cert}3:Heater,{cert}

(4,Thermostat)

[17,240,153,98]

0:AC,{cert}1:MotionSensor,{cert}2:Thermostat,{cert}

(5,Thermostat)

[17,240,153]

RemoveHeater

ReconcilingMultipleViews

41

HeaterThermostatACMotionSensor

Inview(4,Heater)Inview(6,Thermostat)

/home/bonjour/vinfo/(4,Heater)

/home/bonjour/vinfo/(4,Heater)0:Heater,{cert}1:MotionSensor,{cert}

/home/bonjour/(7,Thermostat)/…

Publish:/home/bonjour/vinfo/(7,Thermostat)0:Thermostat,{cert};1:AC,{cert}

3:Heater,{cert}4:MotionSensor,{cert}

Fetch(7,Thermostat)viewinfo andmoveto(7,Thermostat)

Aftergrouppartitionheals,theleaderwithhigherviewnumberor“larger”leadernameisresponsibleformergingtheviews

/home/bonjour/(4,Heater)/…

SynchronizingStateAfterViewMerging

42

Thermostat AC Heater MotionSensor0:Thermostat1:AC

0:Heater1:MotionSensor

[24,19] [23,21] [98,120] [96,121]

0:Thermostat1:AC2:Heater3:MotionSensor

Synchronizeview

[24,19,0,0] [23,21,0,0] [0,0,98,120] [0,0,96,121]

[24,21,98,121]Synchronize

state

SecuringDatasetSynchronization

43

ApplicationTrustAnchor/Home

/Home/Thermostat /Home/AC /Home/Heater

0:/Thermostat,{cert}1:/AC,{cert}2:/Heater,{cert}

/Home/resource/disc/vinfo/(4,/AC)

“10:30AM,Temp:70F”Vector=[15,100,92]

/Home/Thermostat/15HEARTBEATVector=[60,148,135]

/Home/Heater/135

Sign

SignSign Sign

Summary

• Explicitgroupmembershiplist(theview)enablestheuseofversionvectorasaconciserepresentationofthedatasetnamespace

• Event-drivenotificationwithexplicitinformationallowsnodestoretrievenewdataimmediately

• KeepingconsistentviewamongallnodesbyincludingtheviewIDinallnotificationInterests• NodescanretrievetheviewinfoafterreceivingnewviewID

• Publishingallstateinfo(vector,membershiplist)asnamedandsecureddatausingwell-definednamingconvention

44

SimulationStudy

• Methodology• ConductexperimentsusingndnSIM (ns3-basednetworksimulator)• ComparewithChronoSync usingthesameapplication

• Metrics• Datadisseminationdelay:thetimeneededforanynodetoreceivethedataafteritispublished• Synchronizationdelay:thetimeneededfortheallnodesinthegrouptoreceivethedataafteritispublished• Networktraffic:totalnumberofInterestandDatapacketstransmittedinthenetwork

45https://github.com/named-data/ChronoSync

Scenario:smallcampusnetwork

BB1 BB2

DR4DR3

DR1 DR2

GW1 GW2 GW3 GW4 GW5

GW6GW7

Department ADepartment B

Department C

CampusBackbone

10Gbps/5ms

1Gbps/10ms

1Gbps/5ms

EN1 EN2 EN3 EN4 EN5 EN6

EN7EN8EN9EN10

1Gbps/2ms

46

• Applicationrunningon10edgenodesparticipatinginasyncgroup• RTTrange:8ms~68ms

• Twotypesoftraffic:• Lowdatarate:10saverageinter-arrivaltimeforeach• Highdatarate:1saverageinter-arrivaltimeforeach

DataDisseminationDelaywithNoPacketLoss

0 50 100 150 200

0.0

0.2

0.4

0.6

0.8

1.0

Data dissemination delay in VectorSync (ms)

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47

~1.5*MinRTT

~ 1.5*MaxRTT

~1.5*MinRTT

~ 1.5*MaxRTT

DataRate=0.1pps DataRate=1pps

SynchronizationDelayinVectorSync

48

DataRate=0.1pps DataRate=1pps

HigherdatarateinthegroupenablesVectorSync torecoverfrompacketlossfasterbecausethestatevectorcarriedineachdataenablesinconsistencydetection

0 500 1000 1500 2000

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Data synchronization delay in VectorSync (ms)

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Loss rate0%1%5%10%

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●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●● ● ●● ● ● ●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●● ● ● ● ● ●●

Loss rate0%1%5%10%

SynchronizationDelayunderLowDataRate(VectorSync vs.ChronoSync)

49

VectorSync isresilienttosimultaneousupdatebecauseexplicitnotificationallowsreceiverstofetchthenewdataimmediately

0 500 1000 1500 2000

0.0

0.2

0.4

0.6

0.8

1.0


CD

F

●●●●

●●●●●●●●●●●●●●

●●●●●●●●●●

●●●●●●

●●●

●●●●●●●●●●

●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●

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●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●

Loss rate0%1%5%10%

0 500 1000 1500 2000

0.0

0.2

0.4

0.6

0.8

1.0

Data synchronization delay in ChronoSync (ms)

CD

F

●●

●●●●●●●●●●●

●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●

●

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●●●●●●●●●●●●●●● ●●●●●●●● ●●●●● ●●●●● ● ●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●Loss rate

0%1%5%10%

Duetosimutaneous data

NetworkTrafficunderLowDataRate(VectorSync vs.ChronoSync)

50

MainreasonforhigherInterestvolumeinChronoSync:• AdditionalmulticastSyncInterestfordetectingsimultaneousupdates• RecoveryInterestforrepairingconflictingstates

LossRate 0% 1% 5% 10%

PacketType Interest Data Interest Data Interest Data Interest Data

VectorSync 167k 134k 170k 134k 183k 132k 205k 129k

ChronoSync 321k 132k 359k 151k 436k 172k 455k 154k

Totalnumberofpacketsacrossalllinks

SynchronizationDelayunderHighDataRate

51

Underhighdatarate,ChronoSync invokes“recovery”mechanismfrequently,whichprovidessimilarinformationasthestatevectorinVectorSync

0 500 1000 1500 2000

0.0

0.2

0.4

0.6

0.8

1.0


CD

F

●●●●●●●●●

●●●

●●●●

●●

●●●●●●●

●●●

●●●●●●●

●●●●●●●●●

●●●

●●●●●●

●

●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

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●●●●●●●●●●●●●●● ●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●● ● ●● ● ● ●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●● ● ● ● ● ●●

Loss rate0%1%5%10%

0 500 1000 1500 2000

0.0

0.2

0.4

0.6

0.8

1.0


CD

F

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●● ● ● ●●● ● ●

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●●●● ●●●● ●

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●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●● ●●● ● ●●●

Loss rate0%1%5%10%

NetworkTrafficunderHighDataRate

52

LossRate 0% 1% 5% 10%





• HightrafficvolumeinChronoSync duetofrequentinvocationofrecoverymechanism

• TrafficvolumeinVectorSync increasesonlyslightlyduetoInterestretransmission

Summary

• CarryingdatanameexplicitlyinthenotificationInterestenablespromptandefficientdatadissemination,eveninfaceofmultiplesimultaneousdataproducers

• Carryingstatevectorinnodes’dataenablesdetectingandreconcilinginconsistencyinthedatasetnamespace

• HighergroupdatarateenablesVectorSync torecoverfrompacketlossmorequickly

53

EvaluatingViewSynchronization

• Understandingthebehaviorofviewsynchronizationundernodejoining/leavingandpacketloss• Howfastthegroupreactstomembershipchanges• Messagingoverhead• Additionaldelay• Implicationsofprotocolparametersettings

• Resultstobeincludedinthedissertation

54

ComparisonwithExistingProtocols

55

Enumeration

Hashing

IBF

Enumeration

Hashing

IBF

CCNx 0.8Sync

CCNx 1.0Sync

iSync pSync

ChronoSync RoundSync

VectorSync

Long-livedInterest

Notificationdriven

Periodicexchange

Long-livedInterest

Notificationdriven

Periodicexchange

Useapplicationname Namedatasequentially

ComparisonwithExistingProtocols

56

Factors affectingInterestsize

FactorsaffectingDataContentsize InterestOverhead MinData

DisseminationRTT

CCNx 0.8Sync Nodehash Numberofchildnodes Periodic Depending onInterestperiod+treewalk

CCNx 1.0Sync Manifestdigest Total numberofnames Oneperupdate 2.5

iSync IBFdigest IBF(dependingonnumberofnewdata) Periodic Depending onInterest

period+3.5RTT

ChronoSync State digest(withexcludefilter)

Number ofnameswithnewsequencenumbers Long-livedInterest

Minis0.5; canbelongwithsimultaneousdata

publishing

RoundSync Rounddigest(withexcludefilter)

Numberofnameswithnewseq# inaround Two perupdate

Minis1.5;canbelongwithsimultaneousdata

publishing

pSync** IBF(+subscriptionlist) IBF +numberofnewnames Long-livedInterest 1.5

VectorSync Leadername+nodename State vector(small) Oneperupdate

(withheartbeat) 1.5

** pSync doesnotsupportgroupsync

Conclusion

57

Conclusion

• DistributeddatasetsynchronizationisanimportantabstractioninNDNforsupportingdistributedapplications

• Ourcomparativestudyoftheexistingsyncprotocolsidentifiedcommonsyncprotocolframeworkandexposeddifferenttradeoffsintheprotocoldesignchoices

• WedevelopedVectorSync,anewsyncprotocoldesignthatovercomethedrawbacksoftheexistingsyncprotocols• Explicitgroupmembershipmanagement• Explicitnewdatanotification• Detectingandreconcilingdatasetinconsistencyusingversionvector

58

FutureWorks

• Exploringdifferentgrouprendezvousmechanisms• DHT• Viralpropagation

• ApplyingVectorSync toNDNapplications• Routingprotocol• Distributedrepository

59

Publications

60

Ø NDN.JS:aJavascript ClientLibraryforNamedDataNetworking,Infocomm’13Ø NDNFS:anNDN-friendlyFileSystem,NDN-TR-0027,2014Ø MicroForwarder.js:anNDNForwarderExtensionforWebBrowsers,ICN’16

NDNApplications

Ø SecuringBuildingManagementSystemsUsingNamedDataNetworking,IEEENetwork,vol.28,no.3,2014Ø NDN-ACE:AccessControlforConstrainedEnvironmentsoverNamedDataNetworking,NDN-TR-0036,2015Ø ChallengesinIoT NetworkingviaTCP/IPArchitecture,NDN-TR-0038,2016Ø NamedDataNetworkingofThings,IoTDI’16Ø TheDesignandImplementationoftheNDNProtocolStackforRIOT-OS,Globecom’16ICNSRAWorkshopØ Breakingoutofthecloud:LocaltrustmanagementandrendezvousinNamedDataNetworkingofThings,IoTDI’17

IoT overNDN

Ø TheDesignofRoundSync Protocol, NDN-TR-0048,2017Ø ASurveyofDistributedDatasetSynchronizationinNamedDataNetworking,NDN-TR-0053,2017

NDNSync

BackupSlides

61

RoundSync:addressingissuesinChronoSync

• Dividedatapublishingintorounds• Decouplestatenotificationfromupdateretrieval• Stillneedspecialmechanismtoretrievemultipledatainasingleround

62

RN Dataset Digest

…

24 {/TouristA/15,/TouristB/60} D2425 {/TouristC/32} D25

/park/bbs/DATA/25

{/TouristC:32}

DataInterest

Reply

RoundLog /park/bbs/SYNC/[Digest]SyncInterest

JoiningtheGroup

63

MotionSensorThermostatAC Heater

Inview(8,Thermostat) Createview(0,Heater)

Publish:/home/bonjour/vinfo/(0,Heater)0:Heater,{cert}

/home/bonjour/(0,Heater)/Heater/1

/home/bonjour/vinfo/(0,Heater)

Merge(0,Heater)intothegroupandperformviewchange

Nodejoiningishandledinthesamewayasviewmerging

Scenario2:largeISPnetwork

• Randomlypick10“leaf”nodes• RTTrange:111ms~476ms

• Traffic:10sinter-arrivaltimefromeachnode

64N.Stringetal.,“MeasuringISPtopologieswithRocketfuel”,2004

DataDisseminationDelaywithNoPacketLoss

65

~1.5*MinRTT

<1.5*MaxRTTduetocaching

0 200 400 600 800 1000

0.0

0.2

0.4

0.6

0.8

1.0


CD

F

SynchronizationDelay

0 5000 10000 15000 20000

0.0

0.2

0.4

0.6

0.8

1.0


CD

F

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Loss rate0%1%5%10%

66

0 5000 10000 15000 20000

0.0

0.2

0.4

0.6

0.8

1.0


CD

F

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Loss rate0%1%5%10%

NetworkTraffic

67

LossRate 0% 1% 5% 10%





HightrafficvolumeinChronoSync dueto“recovery”mechanism

DatasetSnapshotandPermanentStorage

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Motivation

• Problem:• VectorSync synchronizesamongactivemembers• Someapplicationsmaywanttokeepalldatapublishedinthehistory

• Solution:• Thegroupgeneratesa“snapshot”forthedatasetstate atthebeginningofeachview• Asnapshotisaversionvectorcoveringallthedatapublishedinthegroupbeforetheviewstarts

• A dedicatedrepocollectsdatabasedonthesnapshotandstorepermanently• Newnodesretrievewholedatasetfromtherepotobootstrap

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GeneratingGroupSnapshot

• Beforesyncingdatainanewview,eachnodepublishesitslocalsnapshotintheshareddataset• Localsnapshotpacketspropagatedinthegroupviasync

• LeadercomputesthegroupsnapshotastheJoin oflocalsnapshotsfromall nodesinthecurrentview

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Previousview:(6,/HVAC)[/Thermostat:35,/HVAC:103]

Previousview:(6,/HVAC)[/Thermostat:34,/HVAC:103]

/Thermostatlocalsnapshot /HVAClocalsnapshot /Lamplocalsnapshot

Previousview:(4,/Lamp),(6,/HVAC)[/Thermostat:35,/HVAC:103,/Lamp:55,/LampSwitch:20]

(7,/HVAC)groupsnapshot:

Previousview:(4,/Lamp)[/Lamp:55,/LampSwitch:20]

(7,/HVAC)0:/Thermostat1:/HVAC2:/Lamp

Summary

• Effectiveness• Synchronizinglatestseq#ensuresnodesdiscoverallmissingdata• Periodicheartbeathelpsrecoverfrompacketloss

• Efficiency• Explicitdatanamenotificationenablesfastersync• Simultaneouspublishingdonotinterfere

• Scalability• Membershipmanagementcontrolsstatevectorsize• Largegroupsmayadoptcompressedencoding(e.g.,IBF)

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Distributed Dataset Synchronization in Named Data NetworkingDistributed Dataset Synchronization in Named Data Networking Wentao Shang Final defense 06/01/2017 1

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