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