eitf25 -20151207-10 application layer -2- user applications · application layer-2-user...
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Application Layer-2-
UserApplications
2015,Lecture 10Kaan Bür
EITF25– Internet:TechnologyandApplications
PreviouslyonEITF25
• FromdomainnamestoIPaddresses:DNS
• Hostconfiguration:DHCP
• Debuggingtools:ICMP,ping,traceroot
• World-wideWeb:HTTP2015-12-07 2EITF25– Internet:TechnologyandApplications
ApplicationLayer(1)
Today:ApplicationLayer (2)
• FileTransferProtocol,FTP[F26.2]
• Electronicmail,SMTP,POP,IMAP[S24.1][F26.3]
• Peer-to-peernetworks,P2P[F29.1,F29.5]
• VoiceoverIP,VoIP[S25.2-3][F28.4.4-5]
*[Kihl&Andersson:12.3,12.5-6,12.8]2015-12-07 3EITF25– Internet:TechnologyandApplications
Worldwideweb(www)
• 1989-1990:HTTP,HTMLbyTimBerners-Lee• 1991afirstwebbrowser• 1991wwwgoespublic– http://info.cern.ch– Firstwebsite
• 1991:TheTrojanRoomcoffeepot– http://www.cl.cam.ac.uk/coffee/coffee.html– Firstwebcam(realtimeimages)
• 1993:Mosaicbecomespublic2015-12-07 EITF25– Internet:TechnologyandApplications 4
Worldwideweb(www)
• 1994:PizzaHut(firstonlinewebshop)• 1994:Yahoo• 1995:AltaVista• 1997:AOLinstantmessanger• 1997:sixdegrees.com(firstmodernsocialnet)• 1997:Google
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Thencamethedigitalage...• 1999:Napster• 1999:Blogger• 2001:BitTorrent• 2001:Wikipedia• 2003:Skype• 2003:WordPress• 2004:Gmail• 2004:Flickr• 2005:YouTube• 2005:Facebook• 2006:Twitter• 2008:Spotify• 2009:GoogleDocs• 2009:AngryBirds
See: 10 surprising social media statistics... (2013)2015-12-07 EITF25– Internet:TechnologyandApplications 6
Client/serverparadigm
• Mostearlyapplicationswerebasedonit– http– ftp– e-mail
Request
Reply
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FileTransferProtocol(FTP) - 1971
• Filetransferbetweentwocomputers• TCP/IP
• Notsostraightforward– Fileconventions– Datarepresentations– Directorystructures
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Controlconnection
Dataconnection
FTP:basicmodel
Controlconnection• Openforentiresession• Commands&responses
– ASCII
Dataconnection• Newoneforeachfile
20
21
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FTP:Dataconnection
• Clientissuespassiveopen– SendsPORT#toserver
• Serverissuesactiveopen– server:port20↔client:port#
• Allpreparationsthrough controlconnection
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FTP:Controlconnection
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CO
MM
AN
DS
RES
PON
SES
Electronicmail(e-mail) - 1971
• Thefirste-mailwassentbetweentwocomputersinthesameroom.
• Toseparatetheuserfromthehostcomputer,[email protected]. 132015-12-07 EITF25– Internet:TechnologyandApplications
E-mail:protocolsused• SMTP– Simplemailtransferprotocol
• POP– Postofficeprotocol
• IMAP– Internetmailaccessprotocol
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E-mail:serverarchitecture
Sender&receiverinone
• Notaverygoodrepresentation!
Aholisticview
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INTERNET
Localclient
SMTP(in/out)
POP
Local client
Inte
rnet
SMTP
SMTP
POP
SMTP
Seeyouin15’:)
• Afterthebreak– P2P,BitTorrent– VoIP,Skype
2015-12-07 18EITF25– Internet:TechnologyandApplications
Performancechallenges
• Client/serverarchictures– StandardizedprotocolslikeHTTP– Heavytrafficloadonnetworkinfrastructure– Unicasttransmission– Delaysduetooverloadedaccessnetworks– Singlepointoffailure
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Onesolution:P2P(andcaches)
• Spotify
2015-12-07 EITF25– Internet:TechnologyandApplications 20http://www.csc.kth.se/~gkreitz
Result:betterloaddistribution
212015-12-07 EITF25– Internet:TechnologyandApplicationshttp://www.csc.kth.se/~gkreitz
Peer-to-peer(P2P)paradigm
2015-12-07 EITF25– Internet:TechnologyandApplications
• Userssharingdataformnetworkofpeers• FirstP2Pfilesharing1987–WWIVnetbulletinboardbyWayneBell
• Gainedpopularity1999– NapsterbyShawnFanning
22
P2Pnetworks
Centralised• Directoryserver
Decentralised• Overlaynetwork
– Logicalontopofphysical
• A)unstructured– Nodeslinkedrandomly– Queries floodnetwork
• B)structured– Nodeslinkedwithrules(DHT)– Moreefficientqueryresolving
• Initiallistofnodesprovided
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DistributedHashTables(DHT)
• Ahashfunctionisanalgorithmthatmapsdataofvariablelengthtodataoffixedlength. (m bits)
– NodeID=hash(peerIPaddress)– Key=hash(filename)
• DHTdistributesdataamongasetofnodes.– Eachpeerisresponsibleforaportionofdata.
• DHTroutesaquerytoresponsiblenode– Peershavepartialknowledgeaboutwholenet.
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DHTaddressspace
• NodeID=hash(peerIPaddress)• Key=hash(filename)
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DHTexample
• Examplem=5– NodeID(5)– Key(14)– Ref(17)
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P2Pexample:BitTorrent
• Groupofpeersworktogethertogiveallpeersacopyofsharedfile.– Torrent– Swarm– Seed– Leech– Tracker
• Nodownloadingwholefilefromonepeer
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Tracker
• Provideslistofpeersforgiventorrent
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BitTorrent Server
New peer
VoiceoverIP(VoIP)
SIP
• SessionInitiationProtocol
• IETFstandard
H.323
• Communication(telephone,computer)
• ITU-Tstandard
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• Internettelephony– Usestwoprotocols
SessionInitiationProtocol(SIP)
• Applicationlayerprotocol• Multimediasessionmanagement• Text-basedmessages
• Variousaddresstypes
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H.323
• Communication(telephone,computer)– Gateway=5-layertranslationdevice– Gatekeeper=registrar
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H.323protocols
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ResourcereservationCompressionmethodnegotiation
Connection setupAudioexchange&management
EvolutionofInternetusage
• Trafficvolumesgeneratedbyusers
2015-12-07 EITF25– Internet:TechnologyandApplications
2007
2011
J. Li, A. Aurelius, V. Nordell, M. Du, Å. Arvidsson, M. Kihl: A five year perspective of traffic pattern evolution in a residential broadband access networkFuture Network & Mobile Summit 2012
37
Contentdistributionarchitectures
• Multimedia– Contentstoredinback-endserverclusters(cloud)– Distributedtoclientsuponrequested
2015-12-07 EITF25– Internet:TechnologyandApplications
Internet
Content Clients 38
Example:LivesportchannelatTV4
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National ISPAccess network Modem
Speakers
Cache servers(http)
Production Transmission control
IP multicast network
EncodingEncryption Ingest servers Origin servers
(http)
PC / CE device (TV /
bluray)
Content Distribution
Network (CDN)Ingest servers
(http)39
Summary: ApplicationLayer (2)
• AlittlehistorybehindWWW• Client/serverapplications– ftp,filetransfer– e-mail,messageexchange
• P2Papplications– Bittorrent,filesharing– Skype,Internettelephony
• Streamingmultimediaapplications
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Connectingdevices (1)
ApplicationPresentation
SessionTransportNetwork
LinkPhysical
ApplicationPresentation
SessionTransportNetwork
LinkPhysical
LinkPHY PHY
Sender Receiver
Switch
ProtocolData
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Connectingdevices (2)
ApplicationPresentation
SessionTransportNetwork
LinkPhysical
ApplicationPresentation
SessionTransportNetwork
LinkPhysical
NetworkLink LinkPHY PHY
Sender ReceiverProtocolData
2015-12-07 EITF25– Internet:TechnologyandApplications
Router
44
Router
• usedbetweennetworksusingthesamenetworkprotocol
2015-12-07 EITF25– Internet:TechnologyandApplications
IP network IP network
45
Connectingdevices (3)
ApplicationPresentation
SessionTransportNetwork
LinkPhysical
ApplicationPresentation
SessionTransportNetwork
LinkPhysical
ApplicationP. P.S. S.T. T.
Net NetLink LinkPHY PHY
Sender ReceiverData
2015-12-07 EITF25– Internet:TechnologyandApplications
Gateway
46