Yair Amir - Johns Hopkins Universityyairamir/YairAmir_IPL.pdf · Distributed Systems and Networks lab Department of Computer Science, Johns Hopkins University Yair Amir

DistributedSystemsandNetworkslabDepartmentofComputerScience,JohnsHopkinsUniversity

www.dsn.jhu.edu

YairAmirDonP.GiddensLecture

•  Theoneandonly–MichalMiskin‐Amir•  Theadvisor–DannyDolev•  Theprofessors–

–  M.Melliar‐Smith,L.Moser,K.Birman,A.Brodsky,Y.Yemini

•  Thestudent‐colleagues‐–  R.Borgstrom,J.Stanton,D.Shaw,J.Green,J.Schultz,T.Schlossnagle,A.Peterson–  C.Nita‐Rotaru,C.Danilov,C.Tutu,R.Caudy,A.Munjal,M.Hilsdale–  N.Rivera,J.Lane,R.Musaloiu‐EleNeri,J.Kirsch,M.Kaplan–  D.Obenshain,T.TanQllo

•  Thego‐toexperts‐–  B.Awerbuch,A.Barak,G.Tsudik,S.Goose,A.Terzis,B.Coan,R.Ostrovsky

•  Theentrepreneurs‐–  M.Khan,Y.Javadi,S.Goose

•  TheHopkinsprofessors‐–  B.Awerbuch,G.Mason,R.Kosaraju,S.Smith,M.Goodrich,R.Westgate

•  Theprogrammanagers––  D.Maughan,T.Gibson,C.Landwehr,H.Shrobe

2February16,2012 YairAmir

Asingle,mulQ‐purpose,IP‐basednetwork– EachaddiQonalnodeincreasesitsreachandusefulness(similartoanynetwork)

– EachaddiQonalapplicaQondomainincreasesitseconomicadvantage

– Willthereforeswallowmostothernetworks•  Happened:mailtoe‐mail,PhonetoVoIP,FaxtoPDFs•  Startedtheprocess:TV,variouscontrolsystems•  SQlltocome:Cellphonenetworks


Asingle,mulQ‐purpose,IP‐basednetwork•  Theartofdesign–asuccessfulparadigm

–  Keepitsimpleinthemiddle•  Best‐effortpacketswitching,rouQng(intranet,Internet)

–  Smartattheedge•  End‐to‐endreliability,naming

•  Couldthereforeadaptandscale–  Survivedfor4decadesandcounQng–  Sustainedatleast7ordersofmagnitudegrowth

•  Standardizedandalotridesonit–  Thebasicservicesarenotlikelytochange


•  CommunicaQonpaberns–  FromPoint‐to‐point–topoint‐to‐mulQpoint–tomany‐to‐many

•  Highperformancereliability–  “Fasterthanreal‐Qme”filetransfers

•  LowlatencyinteracQvity–  150mskeystrokemirroring–  100msforVoIP–  80‐100msforinteracQvegames(remotesurgery?)

•  End‐to‐enddependability–  From“Internet”dependability–to“phoneservice”dependability–to

“TVservice”dependability–to“remotesurgery”dependability•  Systemresiliency

–  FromE‐mailfaulttolerance–tofinancialtransacQonsecurity–tocriQcalinfrastructure(SCADA)intrusiontolerance

5YairAmirFebruary16,2012

•  Buildspecializednetworks–  WasdonedecadesbeforetheInternet–  ThinkCable/TVdistribuQon(Satellite+lastmile)–  Extremelyexpensive

•  BuildprivateIPnetworks–  AvoidstheresourcesharingaspectsoftheInternet,solvessomeofthe

scaleissues–  Expensive–  SQllconfinedtobasicIPnetworkcapabiliQes

•  BuildabeberInternet–  ImprovementsandenhancementstoIP(orTCP/IPstack)–  “Cleanslatedesign”

•  Buildoverlaynetworks

6YairAmirFebruary16,2012

•  Overlay paradigm: –  In contrast to “keep it simple in the middle and smart at the edge” –  Move intelligence and resources to the middle

•  Software-based overlay routers working on top of the internet •  Overlay links translated to Internet paths

•  Smaller overlay scale (# nodes) smarter algorithms, better performance, and new services.

February16,2012 YairAmir 7

•  FlexibleRouQng–  RON–resilientrouQngusingalternatepaths[Andersenetal,01]–  XBone–flexiblerouQngusingIPinIPtunneling[Touch,Hotz,98]

•  ContentDistribuQon–  Yoid–host‐basedcontentdistribuQon[Francis00]–  Overcast–reliablemulQcastforhighbandwidthcontentdistribuQon[Jano:

etal,00]–  Bullet–mulQ‐pathdatadisseminaQon[Kos<cetal03]

•  MulQcast–  ESM–providesapplicaQon‐levelmulQcast[Chuetal,00]–  HTMP–interconnectsislandsofIPMulQcast[Zhangetal,02]

•  PeertoPeer–  Chord–logarithmiclookupservice[Stoicaetal,01]–  Kelips–O(1)lookupwithmoreinformaQonstored[Guptaetal,03]

•  GroupCommunicaQon–  TheSpreadtoolkit–scalablewideareagroupcommunicaQonusinganoverlay

approach[Amir,Danilov,Stanton,00]


•  TheOverlayNetworkParadigm•  TheDARPANetworkingChallenge(99‐03)

– OverlayArchitecture–  Low‐latencyreliabletransport

•  TheSiemensVoIPChallenge(03‐06)– Almost‐reliable,real‐Qmetransport

•  TheLiveTimeNetTVChallenge(08‐…)–  FromOverlaystoClouds– UlQmateresiliency,automatedmonitoringandcontrol

•  ThechallengesaheadFebruary16,2012 YairAmir 9

•  ThetradiQonalparadigm(keepitsimpleinthemiddleandsmartattheedge)workswellfortradiQonalapplicaQonsintypicalconnecQvitycondiQons

•  ButnotsowellfortradiQonalapplicaQonsinbadconnecQvitycondiQons

•  AndnotsowellforemergingapplicaQonsintypicalconnecQvitycondiQons


•  50millisecondnetwork–  E.g.LosAngelestoBalQmore–  50millisecondstotellthesenderabouttheloss–  50millisecondstoresendthepacket

•  Atleast100millisecondstorecoveralostpacket


565

5

LAX BWI

•  50millisecondnetwork–  E.g.LosAngelestoBalQmore–  50millisecondstotellthesenderabouttheloss–  50millisecondstoresendthepacket

•  Atleast100millisecondstorecoveralostpacket–  Canwedobeber?


LAX BWI

•  50millisecondnetwork,fivehops–  10millisecondstotellnodeDALabouttheloss–  10millisecondstogetthepacketbackfromDAL

•  Only20millisecondstorecoveralostpacket–  LostpacketsenttwiceonlyonlinkDAL–ATL


56 5

5

LAX PHX DAL ATL DCA BWI

SimulaQon

Latency

February16,2012 14YairAmir

SimulaQon

Latency

Ji@er


SimulaQon SpinesonEmulab

Latency

Ji@er


•  50msnetworkdividedevenlyintoxhops•  Delayedpackets:arriveaNermorethan50+10ms


•  TheSpinesOverlayMessagingsystem– AnOverlaysoNwarerouter(daemon)ontopofUDP–  RunningasanormalInternetapplicaQon

•  Easytouseprogrammingplarorm–  TransparentinterfaceidenQcaltothesocketinterface,givingTCP,UDPandIPMulQcastfuncQonality

•  “Commercialgrade”deployablesystem–  ImprovingapplicaQonperformanceovertheInternet–  Enablingnewservices– Opensource(www.spines.org)








•  Canwemaintaina“goodenough”phonecallqualityovertheInternet?

•  Highqualitycallsdemandpredictableperformance–  VoIPisinteracQve.Humansperceivedelaysat100ms–  Thebest‐effortserviceofferedbytheInternetwasnotdesignedto

offeranyqualityguarantees–  CommunicaQonsubjecttodynamicloss,delay,jiber,pathfailures


PSTN

50msnetworkdelay

•  Localizedreal‐Qmerecoveryonoverlayhops–  Retransmissionisabemptedonlyonce

•  EachOverlaynodekeepsahistoryofthepacketsforwardedinthelast100ms–  Whentheotherendofahopdetectsaloss,itrequestsa

retransmissionandmoveson

–  IftheupstreamnodesQllhasthepacketinitshistory,itresendsit

•  Notareliableprotocol–  NoACKs.Noduplicates.Noblocking.

•  Recoveryworksforhopsshorterthanabout30ms–  Thisisok:overlaylinksareshort!

February16,2012 YairAmir 22€

loss ≈ 2 ⋅ p2

€

retr_ delay = 3 ⋅T + Δ

•  Spinesoverlay–5linksof10mseach•  10VoIPstreamssendinginparallel•  LossonmiddlelinkC‐D


50msnetworkdelay

•  RouQngalgorithmthattakes

intoaccountretransmissions•  WhichpathmaximizesthenumberofpacketsarrivingatnodeEinunder100ms?

•  FindingthebestpathbycompuQnglossanddelaydistribuQononallthepossibleroutesisveryexpensive

•  Weightmetricforlinksthatapproximatesthebestpath


€

Exp_ latency = (1− p) ⋅T + (p − 2 ⋅ p2) ⋅ (3 ⋅T + Δ) + 2 ⋅ p2 ⋅Tmax

•  Localizedreal‐Qmerecoveryonoverlayhops– Retransmissionisabemptedonlyonce

•  FlexiblerouQngmetricavoidscurrentlycongestedpaths– Costmetricbasedonmeasuredlatencyandlossrateofthelinks

– Linkcostequivalenttotheexpectedpacketlatencywhenretransmissionsareconsidered







•  CantheInternetbeanunderlyingnetworkforaliveTVservice?–  Livechanneltransport(BusinesstoBusiness)–  Thevirtualcablecompany(BusinesstoConsumer)–  NextGeneraQonTV(InteracQvity)

•  Requirements–  Scalability:Highcapacityflows,manyany‐to‐manyflows

–  Highavailabilityanduniformdelivery

•  Technologytrends–  Cheaplong‐haulaccessbandwidth–  BroadbandInternetconnecQvitytothehome

–  MulQ‐corecomputerarchitectureFebruary16,2012 27YairAmir

Theserviceproviderpointofview•  AserviceratherthansoNwareorhardware•  Controloverwhereoverlaynodesarelocated

•  MulQplenetworkprovidersineachoverlaynode(SuperNodes)

•  Guaranteedcapacitywithadmissioncontrol

•  MonitoringandControl–nearautomaQon






•  Scalableoverlaynetworkarchitecture– Paralleloverlays

•  Real‐Qmemonitoringandcontrol– Automated–takethehumanoutoftheloop

•  ThreelevelsofprotecQon– Linklevel:real‐QmeprotocolforHD‐TV

– Overlaylevel:responsiveoverlayrouQng– Cloudlevel:NxWayfailoverforoverlayrouters


Network packet loss on one link (assuming 66% burstiness)

Loss experienced by flows on the LTN Network

2% < 0.0003%

5% < 0.003%

10% < 0.03%


Availablelink

SuperNode


• UQlizesmulQpleTier1IPbackbones• OpQmizedoverlaypathsdetermineselectedlinks• AutomaQcallyandinstantaneouslyswitchtoabeberpath

Availablelink Selectedlink

SuperNode



Availablelink Selectedlink DeterioraQnglink

SuperNode




SuperNode




SuperNode





SuperNode







•  Resiliency‐allthewaytointrusiontolerance– Resilientclouds– CriQcalinfrastructure– SKYDA(SCADAintheSky)

•  Timelinessandquality–noendtothat – RemotemanipulaQon

– Remotesurgery– Remotemusictraining?


Documents

Yair Amir - Johns Hopkins Universityyairamir/YairAmir_IPL.pdf · Distributed Systems and Networks lab Department of Computer Science, Johns Hopkins University Yair Amir