Advanced Computer Networks cs538, Spring 2016 @ UIUC
Transcript of Advanced Computer Networks cs538, Spring 2016 @ UIUC
Advanced Computer Networks cs538, Spring 2016 @ UIUC
KlaraNahrstedt
Lecture2Basedon
B.M.Leineretal,“BriefHistoryoftheInternet”,InternetSociety2014C.ParCdge,“FortyDataCommunicaConsResearchQuesCons”,CCR,2011Prior2010-2013,lecturematerialbyBrightenGodfreyandMaNCaesar
Announcements
• SelectreviewsbyJanuary28• FormgroupsandselectlectureasagroupbyJanuary28• ReadpapersforJanuary28lecture
• AprotocolforpacketnetworkintercommunicaCon(CerfandKahn,1974)• TheDesignPhilosophyoftheDARPAInternetProtocols(Clark,1988)
Outline
• HistoryofInternet
• Reviewofbasicconcepts
• Grandchallenges–fewexamples
Visions • VannevarBush,“Aswemaythink”(1945):memex
• J.C.R.Licklider(1962):“GalacCcNetwork”
• ConceptofaglobalnetworkofcomputersconnecCngpeoplewithdataandprograms
• FirstheadofDARPAcomputerresearch,October1962 Bush
Licklider
Circuit switching
1920s
1967
[US Air Force]
InternaConaloperator,NewYorkAT&TSource:hNp://www.corp.aN.com/history/nethistory/switching.html
1935
1961-64: Packet switching
Circuit Switching Packet switching
Physical channel carrying stream of data from source to destination
Message broken into short packets, each handled separately
Three phase: setup, data transfer, tear-down
One operation: send packet
Data transfer involves no routingPackets stored (queued) in each router, forwarded to appropriate neighbor
1961-64: Packet switching
• Keybenefit:StaCsCcalMulCplexing• (whatelse?)
Circuit switching
Time
Packet switching:multiplexed
Time
1961-64: Packet switching
• Concurrentdevelopmentatthreegroups• LeonardKleinrock(MIT):queueing-theoreCcanalysisofpacketswitchinginPh.D.thesis(1961-63)demonstratedvalueofstaCsCcalmulCplexing
• PaulBaran(RAND)• DonaldDavies(NaConalPhysicalLaboratories,UK)
Kleinrock Baran Davies
Baran’s packet switching
Paul Baran, “On distributed communications networks”, Sept. 1962
Baran’s packet switching
Paul Baran, “On distributed communications networks”, Sept. 1962
There is an increasingly repeated statement made that one day we will require more capacity for data transmission than needed for voice. If this statement is correct, then it would appear prudent to broaden our planning consideration to include new concepts for future data network directions. ... New digital computer techniques using redundancy make cheap unreliable links potentially usable. ... Such a system should economically permit switching of very short blocks of data from a large number of users simultaneously with intermittent large volumes among a smaller set of points.
Baran’s packet switching
Paul Baran, “On distributed communications networks”, Sept. 1962
“
”
1965: First computer network
• LawrenceRobertsandThomasMerrillconnectaTX-2atMITtoaQ-32inSantaMonica,CA
• ARPA-fundedproject• Connectedwithtelephoneline
• works,butit’sinefficientandexpensive• confirmedonemoCvaConforpacketswitching
• RobertsuClizedDavies’packetswitchingtheorylate1960’sandbuiltintoARPANET
Roberts
The ARPANET begins
• RobertsjoinsDARPA(1966),publishesplanfortheARPANETcomputernetwork(1967)
• December1968:Bolt,Beranek,andNewman(BBN)winbidtobuildpacketswitch,theInterfaceMessageProcessor(IMP)
• FirstgeneraConofgateways• September1969:BBNdeliversfirstIMPtoKleinrock’slabatUCLA An older Kleinrock
with the first IMP
ARPANET comes alive
Stanford Research Institute (SRI)
“LO”Oct 29, 1969
UCLA
ARPANET grows
• Dec1970:ARPANETNetworkControlProtocol(NCP)
• 1971:Telnet,FTP• 1972:Email(RayTomlinson,BBN)
• 1979:USENET
ARPANET, April 1971
ARPANET grows
ARPANET to Internet
• Meanwhile,othernetworkssuchasPRnet,SATNETdeveloped
• May1973:VintonG.CerfandRobertE.KahnpresentfirstpaperoninterconnecCngnetworks
• ConceptofconnecCngdiversenetworks,unreliabledatagrams,globaladdressing,...
• BecameTCP/IP
Kahn
Cerf
TCP/IP deployment • TCP/IPimplementedonmainframesbygroupsatStanford,BBN,UCL
• DavidClarkguidesarchitecture,implementsitonXeroxAltoandIBMPC
• 1982:InternaConalOrganizaConforStandards(ISO)releasesOpenSystemsInterconnecCon(OSI)referencemodel
• DesignbycommiNeedidn’twin• January1,1983:“FlagDay”NCPtoTCP/IPtransiCononARPANET
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI ReferenceModel’s layers
Growth from Ethernet
• Ethernet:R.MetcalfeandD.Boggs,July1976
• SpanningTreeprotocol:RadiaPerlman,1985
• Madelocalareanetworkingeasy
Metcalfe
Perlman
Growth spurs organic change • Early1980s:Manynewnetworks:CSNET,BITNET,MFENet,SPAN(NASA),...
• Nov1983:DNSdevelopedbyJonPostel,PaulMockapetris(USC/ISI),CraigPartridge(BBN)
• 1984:HierarchicalrouCng:EGPandIGP(latertobecomeeBGPandiBGP)
Postel
Partridge
Mockapetris
NSFNET • 1984:NSFNETforUShighereducaCon
• Servemanyusers,notjustonefield
• Encouragedevelopmentofprivateinfrastructure(e.g.,backbonerequiredtobeusedforResearchandEducaCon)
• SCmulatedinvestmentincommerciallong-haulnetworks
• 1990:ARPANETends• 1995:NSFNETdecommissioned
NSFNET backbone, 1992
Explosive growth! In hosts
Explosive growth!
Inte
rnet
forw
ardi
ng t
able
siz
e
[Huston ’12]Year
(Colors correspondto measurements
from different vantage points)
In networks
Explosive growth! In applications
Morris Internet Worm (1988)World wide web (1989)
MOSAIC browser (1992)Search engines
VoiceRadio
Botnets
Streaming videoSocial networking
Peer-to-peer
The results of your class projects!
In devices & technologies
NATs, firewalls, DPI, ...Wireless everywhereMobile everywhere
Tiny devices (smart phones)
...Giant devices (data centers)
Link speeds 200,000x fasterO(100 million) times as many devices
Cloud computingMobile apps
Huge societal relevance
FridayJune 122009
SaturdayJune 13
SundayJune 14
Routing instabilities and outages in Iranian prefixesfollowing 2009 presidential election
Affe
cted
pre
fixes
[James Cowie,Renesys Corporation]
Huge societal relevance
Rea
chab
le p
refix
es
July - August 2011 [James Cowie,Renesys Corporation]
Reachability to Lybia
Top 30 invenZons of the last 30 years
16.MediaFileCompression17.Microfinance18.PhotovoltaicSolarEnergy19.LargeScaleWindTurbines20.SocialNetworkingviaInternet21.GraphicUserInterface(GUI)22.DigitalPhotography/Videography23.RFID24.GeneCcallyModifiedPlants25.Biofuels26.BarCodesandScanners27.ATMs28.Stents29.SRAM/FlashMemory30.AnC-RetroviralTreatmentforAIDS
1. Internet/Broadband/WorldWideWeb
2. PC/LaptopComputers
3. MobilePhones
4. E-Mail
5. DNATesCngandSequencing/HumanGenomeMapping
6. MagneCcResonanceImaging(MRI)
7. Microprocessors
8. FiberOpCcs9. OfficeSopware
10. Non-InvasiveLaser/RoboCcSurgery11. OpenSourceSopwareandServices12. LightEmiqngDiodes(LEDs)
13. LiquidCrystalDisplays(LCDs)14. GPS15. OnlineShopping/E-Commerce/AucCons
Compiled by the Wharton School @ U Penn, 2009
So we’re done! ... right?
• CoreprotocolschangedliNle,butthecontexthas...• CriminalsandmaliciousparCes• Everyonetryingtogamethesystem• Incrediblegrowth• Constantmobility• Extremecomplexity
• ...andfixingthenetinvolvesfundamentalchallenges• It’sdistributed• Componentsfail• Highlyheterogeneousenvironments• HighlycomplexsystemscomponentsandinteracCons• MustgetcompeCngparCestoworktogether
Review of Basics before Grand Challenges
Layering
• Akindofmodularity• FuncConalityseparatedintolayers
• Layernimplementshigher-levelfuncConalitybyinterfacingonlywithlayern-1
• Hidescomplexityofsurroundinglayers:enablesgreaterdiversityandevoluConofmodules
Application
Transport
Network
Data Link
Physical
Application
Transport
Network
Data Link
Physical
Network
Data Link
Physical
Network
Data Link
Physical
Layering
• Akindofmodularity• FuncConalityseparatedintolayers
• Layernimplementshigher-levelfuncConalitybyinterfacingonlywithlayern-1
• Hidescomplexityofsurroundinglayers:enablesgreaterdiversityandevoluConofmodules
Application
Transport
Network
Data Link
Physical
Application
Transport
Network
Data Link
Physical
Network
Data Link
Physical
Network
Data Link
Physical
Layering
• Akindofmodularity• FuncConalityseparatedintolayers
• Layernimplementshigher-levelfuncConalitybyinterfacingonlywithlayern-1
• Hidescomplexityofsurroundinglayers:enablesgreaterdiversityandevoluConofmodules
Application
Transport
Network
Data Link
Physical
Application
Transport
Network
Data Link
Physical
Network
Data Link
Physical
Network
Data Link
Physical
Layering
• Akindofmodularity• FuncConalityseparatedintolayers
• Layernimplementshigher-levelfuncConalitybyinterfacingonlywithlayern-1
• Hidescomplexityofsurroundinglayers:enablesgreaterdiversityandevoluConofmodules
Application
Transport
Network
Data Link
Physical
Application
Transport
Network
Data Link
Physical
Network
Data Link
Physical
Network
Data Link
Physical
Layering
• Akindofmodularity• FuncConalityseparatedintolayers
• Layernimplementshigher-levelfuncConalitybyinterfacingonlywithlayern-1
• Hidescomplexityofsurroundinglayers:enablesgreaterdiversityandevoluConofmodules
Application
Transport
Network
Data Link
Physical
Application
Transport
Network
Data Link
Physical
Network
Data Link
Physical
Network
Data Link
Physical
Layering Application
Transport
Network
Data Link
Physical
Application
Transport
Network
Data Link
Physical
Network
Data Link
Physical
Network
Data Link
PhysicalTransport
Network
Data Link
Physical
Transport
Network
Data Link
Physical
Tunnel
Common funcZonality & problems
Framing, errors, addressing
Reliability, flow control, ordering, congestion, ...
Application
Transport
Network
Data Link
Physical Encoding of bits Physics
Packets on a ‘wire’
Packets across networksPackets across domains
Process-level communication
Anything you want...
Independent parties, scale, routing
Life, the universe, and everything
Addressing, heterogeneity, routing
Grand Challenges
Grand Challenges
• Widelyrecognizedasamongthemostimportantunsolvedproblemsinafield
• Pvs.NP• naturallanguageunderstanding• bug-freeprograms• movingsocietytocarbon-neutralenergy• prevenCngcancer• ...
Grand Challenges in networking?
• GeqnganAinthisclass?
GC’s in networking
• “WhatI’mworkingon!”• HighlevelobjecCves
• Security&privacy• Reliability• Usability
• DifferentthanPvs.NP:hardtoevendefine“security”;objecCvesinvolvetradeoffs
An Informal Survey
Unreliability: One Example
Internet RouZng
AS 7018AT&T
AS 36561YouTube
AS 698UIUC
eBGP
iBGP
AS11537Internet2
Border Gateway Protocol
BD
A
BD
C
routeselection
ACBD
CAD
Instability causes outages
BD X
C
• Link state changes• Router failures• Config. changes• ...
• Loops• Detection delay• Black holes
AForwarding loop
FAIL
CACBDEventually, control message: Loop detected!
Instability causes outages
Internet
Destinationsite
Source sites
X
[F. Wang, Z. M. Mao, J. Wang, L. Gao, R. Bush SIGCOMM’06]
Instability causes outages
More outages Longer outages[F. Wang, Z. M. Mao, J. Wang, L. Gao, R. Bush SIGCOMM’06]
(...and higher latency, packet reordering,router CPU load during instability)
Failureinjected Outage length (sec)
Many sources of unreliability
• CongesCon• noend-to-endbandwidthreservaConsintheInternet
• ConfiguraConorsopwarebugs• Failuresordelays
• innetwork,DNSservers,caches,applicaConservers,...
Insecurity: one example
Prefix hijacking
• AnyonecanadverCseroutesforanyIPprefix!• HowcanhijackergettheadverCsedroutestoactuallybeusedbyotherASes?
• Announcemorespecific(longer)prefixthanrealowner• Noweveryone’strafficis“blackholed”
• Canprotectagainstthis(SecureBGP),but...• it’snotdeployedtoday• andeventhen,cansCllcleverly(oraccidentally)aNracttrafficandeavesdrop
From hijacking to MITM • August’08,KapelaandPilosov• ManintheMiddle(MITM)aNack
• TraffictoadesCnaConredirected(notblackholed)throughanaNacker
• ANackercanwatcheverythingyoudowithoutyounoCcing
• What’sthekeyproblemhere?
How can attacker forward traffic to destination,if attacker is pretending to be the destination?
Hijacking + eavesdropping • AfindslegiCmatepath
ABDfor128.2.0.0/16
D
CD
BD
CD
ECD
ECD
FCD
D
C
BA
F
E
BGP Announcements
128.2.0.0/16
Selected routes &flow of data
Hijacking + eavesdropping • AfindslegiCmatepath
ABDfor128.2.0.0/16• Asendssemi-bogus
announcementofpathABDfor128.2.0.0/17
• Result:• ASes(hereB)onrealpathkeepusingrealpathbecauseofloopeliminaCon
• AllotherASesuseroutethroughA(/17beats/16)
• AforwardstraffictoB
D
BCEA
BD
BD
EABD
ABD
EABD
D
C
BA
F
E
BGP Announcements
Selected routes &flow of data
128.2.0.0/16
Grand Challenges in networking
• “WhatI’mworkingon!”• NebuloushighlevelobjecCves
• Security&privacy• Reliability• Usability
• WhydoesnetworkinglackacrispGrandChallenge?• Infrastructureneedstosupporthighlydiverseanddynamicgoals,applicaCons,andenvironments
An Informal Survey
• Complexity
Grand Challenges in networking
Meta-challenge:
How do we make the Internetevolvable?