TABLEOFCONTENTS:
1.VideoConferencing
2.ComponentsofaV.C.system
3.Classification
4.Architecture
5.Protocols
6.NetworkTopologies
7.Standards
8.IssuesinImplementation
9.Applications&Conclusion
VideoConferencing
PopularProtocols:
SessionInitiationProtocol:ItisawidelyusedApplicationLayerprotocolforcommunicationsessionslikevoice
andvideocallsoverinternetprotocolcapableofrunningoverTCP,UDPandSCTP.Itisatextbasedprotocol
whichhasmanyelementsbasedonHTTP’srequest/responsemodelalongwithmostofitsheaderfieldsand
rules.TypicalrequestsandresponsesareREGISTER,INVITE,ACK,CANCEL,BYE,Success,Redirectionetc.
Thefunctionoftherequestscanbeeasilyinferredfromthecommanditself.Ithelpsincreating,modifyingand
tearingoffsessionsbetweencallingparties.ThoughithasmanyfeaturesofSS7signalling,SIPisapeertopeer
protocolimplementedattheendpointsofthenetworkincontrasttotheSS7signallingwhichisimplementedin
thecoresystems.ThereasonforitspopularityamongthesubsetofVoIPprotocolshavingmanyotherprotocols
likeMEGACO,H.323etcisthatithasitsrootsinIPnetworkcommunity(designedbyIETF)thusbeingmore
nativethanotherswhichhavetheirrootsintelecommunicationsindustry(designedbyITU).Thestandarddefines
manynetworkentitiesliketheUserAgentattheendpointliketheSIPphone,aProxyserverforroutingrequests,
aregistrarforregisteringURI(UniversalResourceIndicators)fordevices,aSessionBorderControllerforNAT
TraversalandaGatewaytointerfacetheSIPnetworkwithothernetworks.
H.323Protocol:ItisawidelydeployedrecommendationfromITUforvoiceandvideoconferencingbyequipment
manufacturersforinternetreal-timeapplications.ItisapartoftheITU-TH.3Xseriesprotocolsformultimedia
communicationsoverISDN,PSTNand3Gnetworks.IthasH.225.0protocolforRegistration,Admissionand
Status(RAS)signallingandcall-signallingbetweentheuserequipmentandagatekeeperintothenetwork,H.245
controlprotocolformultimediacommunicationandReal-TimeTransportProtocol(RTP)forsendingandreceiving
informationbetweenentities.
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