EITF25 -20151207-10 application layer -2- user applications · Application Layer-2-User Applications 2015, Lecture 10 KaanBür ... Technology and Applications 2 Application Layer

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

FTP

• Session

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Electronicmail(e-mail) - 1971

• Thefirste-mailwassentbetweentwocomputersinthesameroom.

• Toseparatetheuserfromthehostcomputer,[email protected]. 132015-12-07 EITF25– Internet:TechnologyandApplications

1

2

3

4 5 6

7

8

9

E-mail:basicmodel

pull

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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

E-mail:Web-basedservices

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Seeyouin15’:)

• Afterthebreak– P2P,BitTorrent– VoIP,Skype

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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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AsimpleSIPsession

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Trackingthecallee

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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

H.323session

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Counter-example:Skype

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EvolutionofInternetusage

• Trafficvolumesgeneratedbyusers

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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

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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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Appendix

ConnectingDevices

Connectingdevices (1)

ApplicationPresentation

SessionTransportNetwork

LinkPhysical

ApplicationPresentation

SessionTransportNetwork

LinkPhysical

LinkPHY PHY

Sender Receiver

Switch

ProtocolData

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Switch

• usedwithinalocalnetwork

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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

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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

Gateway

• usedbetweennetworksofdifferenttypes

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IP-network Mobile network

47