Transmisión de Datos y Redes de Comunicaciones [Behrouz A. Forouzan - McGraw-Hill]
TSIN02 Internetworking - Linköping University€¢ TCP/IP Protocol Suite, 4th Ed, Behrouz A....
Transcript of TSIN02 Internetworking - Linköping University€¢ TCP/IP Protocol Suite, 4th Ed, Behrouz A....
TSIN02Internetworking
Lecture1-Introduc7on
Peopleinvolvedinthecourse
• RobertForchheimer,lecturer,examiner
• AjmalMuhammad,lecturer,teachingassistant
• NiklasCarlsson,Jan-ÅkeLarsson,specialtopiclecturers• IngemarRagnemalm,mainsupervisor-homeassignment
• Guestlecturer:BjörnRudin,CombitechAB
Lectureprogram
1 Nov3 Introduc7ontoInternet,basicprinciples RF2 Nov8 Network-of-networks,lowerlayers RF3 Nov10 TransportandApplica7onlayers RF4 Nov15 Op7calNetworking–Components AM5 Nov17 Op7calnetworking–Internetbackbone AM6 Nov22 Networkeconomics AM7 Nov24 Datacenternetworks AM8 Nov30 Sourcecodingandchannelmodeling RF9 Dec1 Streamingvideo NC10 Dec6 Networksecurity JÅL11 Dec8 Guestlecture12 Dec13 Reserve
Lecture DateTopic Lecturer
Courseorganiza7on• Lectureandproblemsolvingclasses• Examina7on
– Wri^enexam(4.5hp)– Homeassignment(1.5hp)
• Allinfoisatcoursewebpage• h^p://www.icg.isy.liu.se/en/courses/tsin02/• Schedule• Literature,addi7onalreadings• Lectureslides• Problemsfortheproblemclasses• Guidelinesforthehomeassignment• Previousexams• News
Literature• TCP/IPProtocolSuite,4thEd,BehrouzA.Forouzan(maincourse
book)
• NetworkedLife,20Ques7onsandAnswers,MungChiang,CambridgeUniversityPress(specificchapters:11,12,16,17,20)
• Op7calNetworks:APrac7calPerspec7ve,3rdEdi7on,RajivRamaswami(Specificchapters:1,7,10)
• Lecturematerialandproblemclassesmaterialarethemostimportant!
• Alterna7veliterature:Seecoursehomepage
TSIN02collec7onofformulas
• Willbepostedontheweb
• YouareexpectedtobringtheTSIN02collec7onofformulasyourselftotheexam!
Whattoexpectfromthecourse
• Nopriornetworkingknowledgeneeded.
• Thecourseisbroadbuthasafocusonthelowernetworklayers.
• Aierthecourse,youwillunderstandthemainprinciplesofInternet.Youwillalsohavesomespecificinsightintoop7calfibernetworks,radioaccess,sourcecoding,networkeconomics,special-purposenetworksfordatacentersandInternet-of-Things.
• Sufficientlearningofinter-networkinglanguage,words,andabbrevia7ons,tobeabletocommunicatewiththepeopleinthenetworkingfield.Fewprotocoldetails.
• Somemathema7caldescrip7onsandmodelsthatareusedinthenetworkingfield.
• Thelessonsmaybetrea7ngcomplementarymaterial,nottreatedinthelectures,andviceversa.
Homeassignment–onlinePac-ManorFutureInternet
• Detailedguidelinesonhomepage
• Findpartners,youworkingroupsof4students
• Chooseassignment(onlinePac-MangameorFutureInternet)
• NotlaterthanNovember9:Announceyourgroupusingthesign-uppage.
• Labassistantwillgetbacktoyouassoonaspossibleperemailtotellwhowillbeyoursupervisor,aswellastheemailofyoursupervisor.
• Checkpoint,notlaterthanNovember21:Sendanoutlineofthereport,markedwithyourgroupnumber,bymailtoyoursupervisorasapdffilea^achment.
– Thepurposeoftheoutlineistoshowthatyouhavestartedtoworkwiththeassignmentandhassomeini7alplan.
– YoursupervisorwillgetbacktoyouassoonaspossiblewithanOKorcommentsaboutthingstotakeintoconsidera7on.Youmaybookashortermee7ngwithyoursupervisorforfurtherdiscussion.
Homeassignmentcont’d• NotlaterthanDecember7:Printoutormailthefinalreporttoyour
supervisor.
• Thehand-inofthereportwillbegradedP=Pass,C=ComplementorF=Fail.ThegradedreportwillbehandedbacktoyouonDecember12atthelatest.
• Ifyouneedtocomplementyourreport,thecomplementedreportmustbehandedinnotlaterthanJanuary20.Youareallowedtobookashortmee7ngwithyoursupervisorun7lDecember19,ifyouhavesomeques7onsregardingimprovementofthereport.ThegradedreportswillbehandedbacktoyouonJanuary31.
• Detailedinfooncoursehomepage!
Lectureoutline
• Courseinfo• Internet–backgroundandhistory• Thebasicprinciples• Layers–frommodula7ontoapplica7on• Internetusage• Internetdevices–someexamples
Whatisinter-networking?
“Theartandscienceofconnec7ngindividuallocal-areanetworks(LANs)tocreatewide-areanetworks(WANs),andconnec7ngWANstoformevenlargerWANs.”
fromtheWebopediaComputerDic@onary
Oneexample:TheInternet
Picturefromwikipedia.se:“Internet”
NumberofInternethosts
• 1981:213hosts• 2001:100million• 2015:1billion
Secondexample:Thetelephonenetwork
Sizeofthetelephonenetwork
Thefixedphones(landlines)aloneareasmanyasthecurrentnumberofhostsonInternet.
Trafficcomparison
Internettrafficexceedsphonetrafficbyfar!
Internet-of-things(IoT)
Ericssonpredictsthatintheyear2020wewillhave50billiondevicesconnectedtoInternet!
Inter-networkstoday• ThePublicSwitchedTelephone
Network(PSTN)Circuit-switched:bandwidth,delayanderrorrateguarantees
• TheInternetPacket-switched,connec7on-less,noQualityofService(QoS)guarantees
QoSnetwork
Best-effort
address data
WhyfocusonInternetinthiscourse?
• TheInternetcarriesbyfarmoredatathanPSTNtoday
• Moreversa7le/flexiblethanPSTN
• InternetprovidesmoreservicesthanPSTN.YoucanusevoiceoverIP(VoIP=namefortechnologyandprotocolsforvoiceoverIP).
• Wewillhoweverdiscusscircuit-switchednetworksalso,par7cularlynewop7calfiberproposals,aswellasIPv6,thenewversionoftheIPprotocolwhichisbecomingincreasinglyconnec7on-oriented.
BriefhistoryoftheInternet• 1964:LeonardKleinrockpresentsamathema7caltheoryfor“messageswitching”
• 1969:(AdvancedResearchProjectsAgencyNetwork-ARPANET),fournodesatAmericanUniversi7esbasedonthenewconceptofPacketswitching
• 1974:VintCerfandRobert(Bob)Kahn,TransmissionControlProtocol(TCP).CerfandKahnworkedinaprojectcalledtheInterneungproject,wan7ngtoconnectdifferentnetworks
• 1977:Firstinternetwiththreedifferentnets:ARPANET,packetradioandpacketsatellite
• Late1970’s:TCPdividedintoTCPandtheInternetprotocol(IP)!
• 1980’s-:TheInternet–acollec7onofnetworks,communica7ngusingtheTCP/IPprotocols
• 1995:CompaniesknownasInternetserviceproviders(ISPs)startedofferingusersaccesstotheInternet.
Inter-networkingterms• Anend-userdevice(computer,smart-phone):ahost
• Connec7ngtwohosts:alink
• Connec7ngseveralhosts:anetwork
• Connec7ngnetworks:inter-networking(verb)
• Aninter-network(inter-net):anetworkofnetworks
• Theworld’slargestinter-network:Internet
• Border(“Edge”)partofaglobalnetwork:Accessnetwork
• Innerpartofaglobalnetwork:Core(“Backbone”)network• Asetofrulesforcommunica7on:aprotocol
• Anagreed-uponprotocol:astandard
• NamefortheprotocolsthatarethefundamentoftheInternet:TheTransmissionControlProtocol(TCP)/InternetProtocol(IP)protocolsuite,cfbook7tle.
mobile network
global ISP
regional ISP
home network
institutional network
Figurefrom:J.FKuroseandK.W.Ross,ComputerNetworking:ATop-DownApproach
Connec7onlessandconnec7on-orientedservices
• Circuit-switchednetwork:Physicalresourcesalongthepropaga7onpatharereserved.
• Qualityofservice(QoS):toguaranteeacertainlevelofperformancetoadataflow.Someservices,e.g.delayandbandwidthareguaranteed.
• Packet-switchednetworkcanbeeither– connecMon-less– connecMon-oriented/thevirtualcircuitapproach
ConnecMon-less:Resourcesalongthepropaga7onpatharenotreserved.ConnecMon-oriented:Aconnec7onservicethatreservesresourcesalongthepropaga7onpathbutmaynotcoveralldemandsonafullcircuit-switchednetwork.
Communica7onstandards• Standardiza7onorganiza7ons:govermental/companies/interna7onal
• InternetEngineeringTaskForce,(IETF),partoftheInternetSociety,non-profitorganiza7on,V.CerfandB.Kahninvolvedinthestartup
• IETFpublishedRequestforComment(RFC),seewww.rfc-editor.org,protocolmaybecomestandardaierdifferentmaturitylevels
• RFC2026:specifiestheprocessforthestandardiza7onofallprotocols
• RFC675:“Specifica7onofInternetTransmissionControlProtocol”,thefirstTCPversion
• Ins7tuteofElectricalandElectronicsEngineers(IEEE):Ethernet,WiFi
• Interna7onalTelecommunica7onsUnion(ITU),UnitedNa7ons,e.g.IMT-Advanced,requirementswhich3rdGenera7onPartnershipProjects(3GPP)LongTermEvolu7on(LTE)triestofulfill.
• Interna7onalstandardiza7onOrganisa7on(ISO)issuesstandardsinmanyareas,alsointelecommunica7onsuchastheOSIlayerednetworkmodelandMPEGvideostandards.
Internetadministra7on
• Internetsociety,withe.g.IETF
• InternetCorpora7onforAssignedNamesandNumbers(ICANN),nonprofitprivateorganiza7on.E.g.:– IPaddressblockalloca7onstoInternetserviceproviders(ISPs)
– Mappingbetweenhuman-andcomputer-readableaddresses…(“liu.se”->130.236.5.66)
Internet–thebasicprinciples
• Anetworkofnetworks• Packetswitching• Unifiedaddresses(IPaddress)• Layeredprotocols
“Anetworkofnetworks”
access net
access net
access net
access net
access net
access net
access net
access net
access net
access net
access net
access net
access net
access net access
net
access net
…
… … …
…
ISP B
ISP A
ISP C
IXP
IXP
peering link
Internet exchange point
ISP=InternetServiceProvider Slideadaptedfrom:J.FKuroseandK.W.Ross,ComputerNetworking:ATop-DownApproach
InternetServiceProviders
accessISP
accessISP
accessISP
accessISP
accessISP
accessISP
accessISP
accessISP
RegionalISP RegionalISP
IXP IXP
Tier1ISP Tier1ISP Google
IXP
– “Tier 1” commercial ISPs (e.g., Level 3, Sprint, AT&T, NTT), national & international coverage
– content provider network (e.g, Google): private network that connects it data centers to Internet, often bypassing tier-1, regional ISPs
Slideadaptedfrom:J.FKuroseandK.W.Ross,ComputerNetworking:ATop-DownApproach
ExampleTier-1ISP:Sprint
Packetswitchingvscircuitswitching
example:! 1Mb/slink! eachuser:
• 100kb/swhen“ac7ve”• ac7ve10%of7me
• circuit-switching:– 10users
• packetswitching:– with35users,probability>10ac7veatsame7meislessthan.0004*
Commonopinion:packetswitchingallowsmoreuserstousethenetworkHowever,theissueisnotthatsimple…
Q1:whathappensif>35users?
Q2:whatiftherateforCScanbechoseninincrementsof10kb/s?
* Based on i.i.d assumption with probability P = 0.1
N users
1 Mbps link
…..
• greatfor(random)burstydata– resourcesharing– simpler,nocallsetup
• excessiveconges7onpossible– packetdelayandlossmayappear– protocolsneededforreliabledatatransfer,conges7oncontrol
• Q:Howtoprovidecircuit-likebehavior?– bandwidthguaranteesneededforaudio/videoapps– s7llanunsolvedproblem(seelectures8and9)
Packetswitching-Proper7es
IPv4addressing
• Eachhostisassigneda32bitIPaddress
• 232≈4.3billionpossibleaddresses/hosts
• Do^eddecimalnota7on,e.g.128.11.3.31
• AnIPdatagramhasasourceandades7na7onaddress
preamble dest.addr sourceaddr data checksum
IPaddresses:howtogetone?
Q:HowdoesahostgetitsIPaddress?• hard-codedbysystemadmin
– Windows:control-panel->network->configura7on->tcp/ip->proper7es– UNIX:/etc/rc.config
• DHCP:DynamicHostConfigura7onProtocol:dynamicallygettheaddressfromaserver– “plug-and-play”
Protocollayering
layers: each layer implements a service – via its own internal-layer actions – relying on services provided by layer below
Networks are complex, with many “pieces”:
– hosts – routers – links of various media – applications – protocols – hardware, software
Question: is there any hope of organizing the structure
of a network?
…. or at least our discussion of networks?
Slideadaptedfrom:J.FKuroseandK.W.Ross,ComputerNetworking:ATop-DownApproach
TCP/IPprotocolsuite
Encapsula7onEverynewlayerencapsulatespreviouslayerdatawithaheader
Layeringpros&cons• Awaytostructureacomplexsystem
– Simplifiestherela7onshipsbetweentheparts
• Modulariza7oneasesmaintenanceandupda7ngofsystemparts– Changeofpartsononelevelistransparenttotherestofthesystem
• Layeringintroducesconstraints–mayleadtosubop7malperformance(e.g.videotransmission)!–Lowerlayerunawareofreal-7merequirementoftheapplica7on
Layer1:Physicallayer
Howtoputdigitalbitsontoananalogsignalwaveform(modula7on).
Example:-On-Offswitching(wire,fiber)-Amplitude/frequency/phasemodula7onofasinewave(radio,wire)-Cable/Connectorstandards(e.g.CAT5,RJ-45…)
Layer2:LinklayerSendingdata(aframe)betweentwonetworkinterfaces• Single-hopaddressing,theMACaddress• Handlingmul7pleaccess
– FDMA,TDMA,CSMA• Handlingerrors
– FEC,ARQ
Layer3:Networklayer
Sendingapacket(datagram)betweentwocomputers
• UnderstandingtheIPaddress• Rou7ngofpackets
logical end-end transport - hosts
source
network data link physical
network data link physical
des7na7on
Layer4:Transportlayer• Sendingdata(segment)betweentwocomputerprocessesusingtheportnumber
• UDPfor“besteffort”packets
• TCPfor“reliable”connec7on
application transport network data link physical
logical end-end transport - processes application transport network data link physical
source des7na7on
Layer5:Applica7onlayer
Sendingdata(message)betweencomputerapplica7ons.Example:-Emailservice(SMTPprotocol)-Filetransport(FTPprotocol)-Webbrowsertoserver(HTTPprotocol)
Internetusage-bytraffic2013
Onlinegaming video
Web,email,dataFilesharing
Videoispredictedtoamountto>80%bytheyear2018.Thetwomaintrafficclassesarehighlyji^ersensi7ve(video)ordelaysensi7ve(gaming)!
Totaltraffic:35EB/Months*Inaddi7on,15EB/MonthuseTCP/IPforclosed-networks(IP-TV)
*EB:Exabytes=1018bytes
Real-7medemands• Networkgaming,audioandvideoconferencingandVideo-
on-demand(VoD)areexamplesofreal-7meservices• Theseputpar7cularrequirementsonthenetwork,suchas
delayanderrorbehavior
• Tradeoff–retransmitlostpacketsoradderrorcorrec7onorconcealtheerrors.Tobefurtherdiscussedinlaterlectures.
Video Clip
Video Stream- ing (VoD)
Non-cri7cal
Surveil- ance, Web- camera
TV- Over- IP
Marginal
Audio-, Video- phone
Video- Confer- encing
Video games
Cri7cal
Delay sensitivity of real-time media applications
Video mail
sek ms
IPv6
• IPversion6isanextensionofIPv4• 128-bitaddresses.2128≈3.4*1038insteadof4.2*109addressesinIPv4!
• IPv6wasdefinedalreadyin1998• Asof2016about12%ofdomainnamesuseIPv6
• MobilenetworkLTEisbasedonIPv6
• IoTisexpectedtospeedupthedeploymentofIPv6
ExampleofInternetdevices
Mostofthetechnicaltermswillbeexplainedinthenextlecture!
ADSL
• Asymmetricdigitalsubscriberline(ADSL)• Exampleathome:Telia/Tele2ADSLmodem• Accesscontrol:FDM/TDM• UseoffrequenciesnotusedduringPSTNvoicecall
• FEC(Forwarderrorcorrec7on)
DOCSIS
• DataOverCableServiceInterfaceSpecifica7on(DOCSIS)
• Exampleathome:Comhem
• Accesscontrol:FDM/TDM
• UseofbandwidthnotusedbycableTV
• FEC
Tradi7onalEthernet,IEEE802.3
• Home/officelocalareanetworks(LANs):e.g.fromADSLmodemtoacomputer
• 100BASE-TXflavorcommon,100Mbit/s
• Overcopperwire• AccesscontrolCSMA-CD(errordetec7on,ARQ)
• CAT5,CAT6cable,RJ45connector
IEEE802.11=WiFi
• CSMA-CAmethod2
• FEC
• Exampleathome:wirelesshomenetwork(e.g.fromADSLmodemtohomePC)
Cellular(mobile)devices
• GSM:TDMA,FEC
• LTE:TDMA/FDMA,FEC
Internet-of-things
• M2Musingcellularnetworks
• Localnetworks:Bluetooth,Zigbee,…
• Example:Electricitymonitor
Fiberop7ccommunica7on
• Internetcore:SONETOC-768:40Gbit/s
• FEC
Fiber-op7ccablesunderseas