47
Application Layer -2- User Applications 2015, Lecture 10 Kaan Bür EITF25 – Internet: Technology and Applications
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
2015-12-07 EITF25– Internet:TechnologyandApplications 5
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
2015-12-07 EITF25– Internet:TechnologyandApplications 7
FileTransferProtocol(FTP) - 1971
• Filetransferbetweentwocomputers• TCP/IP
• Notsostraightforward– Fileconventions– Datarepresentations– Directorystructures
2015-12-07 EITF25– Internet:TechnologyandApplications 8
Controlconnection
Dataconnection
FTP:basicmodel
Controlconnection• Openforentiresession• Commands&responses
– ASCII
Dataconnection• Newoneforeachfile
20
21
2015-12-07 EITF25– Internet:TechnologyandApplications 9
FTP:Dataconnection
• Clientissuespassiveopen– SendsPORT#toserver
• Serverissuesactiveopen– server:port20↔client:port#
• Allpreparationsthrough controlconnection
2015-12-07 EITF25– Internet:TechnologyandApplications 10
FTP:Controlconnection
2015-12-07 EITF25– Internet:TechnologyandApplications 11
CO
MM
AN
DS
RES
PON
SES
FTP
• Session
2015-12-07 EITF25– Internet:TechnologyandApplications 12
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
2015-12-07 EITF25– Internet:TechnologyandApplications 14
E-mail:protocolsused• SMTP– Simplemailtransferprotocol
• POP– Postofficeprotocol
• IMAP– Internetmailaccessprotocol
2015-12-07 EITF25– Internet:TechnologyandApplications 15
E-mail:serverarchitecture
Sender&receiverinone
• Notaverygoodrepresentation!
Aholisticview
2015-12-07 EITF25– Internet:TechnologyandApplications 16
INTERNET
Localclient
SMTP(in/out)
POP
Local client
Inte
rnet
SMTP
SMTP
POP
SMTP
E-mail:Web-basedservices
2015-12-07 EITF25– Internet:TechnologyandApplications 17
Seeyouin15’:)
• Afterthebreak– P2P,BitTorrent– VoIP,Skype
2015-12-07 18EITF25– Internet:TechnologyandApplications
Performancechallenges
• Client/serverarchictures– StandardizedprotocolslikeHTTP– Heavytrafficloadonnetworkinfrastructure– Unicasttransmission– Delaysduetooverloadedaccessnetworks– Singlepointoffailure
2015-12-07 EITF25– Internet:TechnologyandApplications 19
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
2015-12-07 EITF25– Internet:TechnologyandApplications 23
DistributedHashTables(DHT)
• Ahashfunctionisanalgorithmthatmapsdataofvariablelengthtodataoffixedlength. (m bits)
– NodeID=hash(peerIPaddress)– Key=hash(filename)
• DHTdistributesdataamongasetofnodes.– Eachpeerisresponsibleforaportionofdata.
• DHTroutesaquerytoresponsiblenode– Peershavepartialknowledgeaboutwholenet.
2015-12-07 EITF25– Internet:TechnologyandApplications 24
DHTaddressspace
• NodeID=hash(peerIPaddress)• Key=hash(filename)
2015-12-07 EITF25– Internet:TechnologyandApplications 25
DHTexample
• Examplem=5– NodeID(5)– Key(14)– Ref(17)
2015-12-07 EITF25– Internet:TechnologyandApplications 26
P2Pexample:BitTorrent
• Groupofpeersworktogethertogiveallpeersacopyofsharedfile.– Torrent– Swarm– Seed– Leech– Tracker
• Nodownloadingwholefilefromonepeer
2015-12-07 EITF25– Internet:TechnologyandApplications 27
Tracker
• Provideslistofpeersforgiventorrent
2015-12-07 EITF25– Internet:TechnologyandApplications 28
BitTorrent Server
New peer
VoiceoverIP(VoIP)
SIP
• SessionInitiationProtocol
• IETFstandard
H.323
• Communication(telephone,computer)
• ITU-Tstandard
2015-12-07 EITF25– Internet:TechnologyandApplications 29
• Internettelephony– Usestwoprotocols
SessionInitiationProtocol(SIP)
• Applicationlayerprotocol• Multimediasessionmanagement• Text-basedmessages
• Variousaddresstypes
2015-12-07 30EITF25– Internet:TechnologyandApplications
AsimpleSIPsession
2015-12-07 31EITF25– Internet:TechnologyandApplications
Trackingthecallee
2015-12-07 32EITF25– Internet:TechnologyandApplications
H.323
• Communication(telephone,computer)– Gateway=5-layertranslationdevice– Gatekeeper=registrar
2015-12-07 33EITF25– Internet:TechnologyandApplications
H.323protocols
2015-12-07 34EITF25– Internet:TechnologyandApplications
ResourcereservationCompressionmethodnegotiation
Connection setupAudioexchange&management
H.323session
2015-12-07 35EITF25– Internet:TechnologyandApplications
Counter-example:Skype
2015-12-07 EITF25– Internet:TechnologyandApplications 36
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
2015-12-07 EITF25– Internet:TechnologyandApplications
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
2015-12-07 EITF25– Internet:TechnologyandApplications 40
Appendix
ConnectingDevices
Connectingdevices (1)
ApplicationPresentation
SessionTransportNetwork
LinkPhysical
ApplicationPresentation
SessionTransportNetwork
LinkPhysical
LinkPHY PHY
Sender Receiver
Switch
ProtocolData
2015-12-07 EITF25– Internet:TechnologyandApplications 42
Switch
• usedwithinalocalnetwork
2015-12-07 EITF25– Internet:TechnologyandApplications 43
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
Gateway
• usedbetweennetworksofdifferenttypes
2015-12-07 EITF25– Internet:TechnologyandApplications
IP-network Mobile network
47
![09 Application [Kompatibilitätsmodus] · Chapter 9 Internet Application Layer Principles of network applications Important application protocols Socket programming Acknowledgement:](https://static.documents.pub/doc/80x56/60528b21d055422a773e9723/09-application-kompatibilittsmodus-chapter-9-internet-application-layer-principles.jpg)
