Real Time Communications

Real Time Real Time CommunicationsCommunications

Presented by Sebastian NeagaPresented by Sebastian Neaga

Presentation OverviewPresentation Overview

IntroductionIntroduction Applications and TechnologiesApplications and Technologies

Instant Messaging and ChatInstant Messaging and Chat Video ConferencingVideo Conferencing VoIP and IP TelephonyVoIP and IP Telephony Grid ComputingGrid Computing

In-depth look at VoIPIn-depth look at VoIP

TodayToday

Applications: Applications: Instant Messaging and ChatInstant Messaging and Chat

Communication PrerequisitesCommunication Prerequisites ArchitectureArchitecture

Client/ServerClient/Server Mixed Client/Server and Client-to-ClientMixed Client/Server and Client-to-Client Pear-to-pearPear-to-pear

StandardsStandards Internet Relay Chat (IRC)Internet Relay Chat (IRC) T.120 (Data protocol for multimedia)T.120 (Data protocol for multimedia)

Applications: Applications: Video ConferencingVideo Conferencing

What is Video ConferencingWhat is Video Conferencing Problems with NAT and Problems with NAT and

Firewall?Firewall? International Telecommunication International Telecommunication

UnionUnion

Applications: Applications: Video Conferencing (cont.)Video Conferencing (cont.) H.310 H.310 Broadband audiovisual communication Broadband audiovisual communication

systems and terminalssystems and terminals H.320 H.320 Narrow-band visual telephone systems Narrow-band visual telephone systems

and terminal equipmentand terminal equipment H.321 H.321 Adaptation of H.320 visual telephone Adaptation of H.320 visual telephone

terminals to B-ISDN environmentsterminals to B-ISDN environments H.322 H.322 Visual telephone systems and terminal Visual telephone systems and terminal

equipment for local area networks equipment for local area networks which provide a guaranteed quality of which provide a guaranteed quality of serviceservice

H.323 H.323 Packet-based multimedia Packet-based multimedia communications systemscommunications systems

H.324 H.324 Terminal for low bit-rate multimedia Terminal for low bit-rate multimedia communicationcommunication

T.120 T.120 Data protocols for multimedia Data protocols for multimedia conferencingconferencing

Applications: Applications: VoIP and IP TelephonyVoIP and IP Telephony

VoIP and IP Telephony are VoIP and IP Telephony are forms of communications over forms of communications over Internet Protocols (IP) rather Internet Protocols (IP) rather than over the Public Switched than over the Public Switched Telephone Network (PSTN)Telephone Network (PSTN)

VoIP focuses on LAN’s where VoIP focuses on LAN’s where the IP Telephony focuses on the IP Telephony focuses on replacing the PSTN networksreplacing the PSTN networks

Applications: Applications: VoIP and IP Telephony (cont.)VoIP and IP Telephony (cont.)

Basic ConceptsBasic Concepts Conversion analog signals to digital format using Conversion analog signals to digital format using

CODECs from the CODECs from the G.7xx family Translation of digital signals to IP packetsTranslation of digital signals to IP packets Transmission of IP packets over the InternetTransmission of IP packets over the Internet

Communication ConceptsCommunication Concepts Easy way to setup and end a callEasy way to setup and end a call Making calls should be as simple as dialingMaking calls should be as simple as dialing Directory servicesDirectory services

Applications: Applications: VoIP and IP Telephony (cont.)VoIP and IP Telephony (cont.)

VoIP implementationVoIP implementation

Applications: Applications: VoIP and IP Telephony (cont.)VoIP and IP Telephony (cont.) IP Telephony ImplementationIP Telephony Implementation

Media Gateway (MG)Media Gateway (MG) provides translations between circuit switched provides translations between circuit switched

networks and packet switched networks in terms networks and packet switched networks in terms of media flowsof media flows

sends notification to the MGC about endpoint sends notification to the MGC about endpoint eventsevents

execute commands from the MGCsexecute commands from the MGCs Media Gateway Controller or call agent (MGC)Media Gateway Controller or call agent (MGC)

provides call signaling, control and processing provides call signaling, control and processing intelligence to the gatewayintelligence to the gateway

sends and receives commands to/from the sends and receives commands to/from the gatewaygateway

Signaling Gateway (SG)Signaling Gateway (SG) provides signalling translations between circuit provides signalling translations between circuit

switched networks and packet switched networks. switched networks and packet switched networks.

Applications: Grid ComputingApplications: Grid Computing

Distributed ComputingDistributed Computing Point of Sale terminalsPoint of Sale terminals Virtual Organization (VO)Virtual Organization (VO) Third Party Data ManipulationThird Party Data Manipulation

VoIPVoIP

AproachesAproaches Complex Protocol/Simple ArchitectureComplex Protocol/Simple Architecture Complex Architecture/Simple ProtocolComplex Architecture/Simple Protocol

StandardsStandards H.323 is a standard developed by the H.323 is a standard developed by the

International Telecommunications Union International Telecommunications Union which defines a group of protocols over which defines a group of protocols over the Packet Based Networks (PBN) the Packet Based Networks (PBN) which may not necessarily provide which may not necessarily provide guarantee quality of service guarantee quality of service

VoIPVoIP

H.323H.323 Specification of the architectureSpecification of the architecture H.225H.225 Call control, call setup, and packetization Call control, call setup, and packetization

and synchronization of media streamand synchronization of media stream H.235H.235 Security protocol for authentication, Security protocol for authentication,

integrity, privacy, etc.integrity, privacy, etc. H.245H.245 Capability exchange communication and Capability exchange communication and

mode switchingmode switching H.450H.450 Supplementary services including call Supplementary services including call

holding, transfer, forwarding, etc.holding, transfer, forwarding, etc. H.246H.246 Interoperability with circuit-switched Interoperability with circuit-switched

servicesservices H.332H.332 For large size conferencingFor large size conferencing H.26xH.26x Video codecs (H.261, H.263)Video codecs (H.261, H.263) G.7xxG.7xx Audio codecs (G.711, G.723, G.729, etc.)Audio codecs (G.711, G.723, G.729, etc.)

VoIPVoIP

StandardsStandardsSession Initiation Protocol (SIP) Session Initiation Protocol (SIP)

developed by The Internet developed by The Internet Engineering Task Force (IETF) is Engineering Task Force (IETF) is an application layer protocol that an application layer protocol that defines the initiation, modification defines the initiation, modification and termination of multimedia and termination of multimedia communications communications

VoIPVoIP

UAC (User Agent Client)- the end-user system sending SIP requests UAC (User Agent Client)- the end-user system sending SIP requests (initiating or terminating a call);(initiating or terminating a call);

UAS (User Agent Server)- the end-user system handling call requests UAS (User Agent Server)- the end-user system handling call requests (receiving or terminating a call);(receiving or terminating a call);

UA (User Agent) - the combination of UAC and UAS;UA (User Agent) - the combination of UAC and UAS; Proxy Server (PS)) - a network server handling UA requests and Proxy Server (PS)) - a network server handling UA requests and

responses in proxy mode (acting as both a server and a client to make responses in proxy mode (acting as both a server and a client to make requests on behalf of other clients);requests on behalf of other clients);

Redirect Server (RS)- a network server handling user location services in Redirect Server (RS)- a network server handling user location services in redirect mode (unlike the PS that initiates its own SIP request);redirect mode (unlike the PS that initiates its own SIP request);

Registar Server - a network server able to accept UA registrations;Registar Server - a network server able to accept UA registrations; Location Server - a network server able to provide user location services Location Server - a network server able to provide user location services

(in order to obtain information about a called party's possible location).(in order to obtain information about a called party's possible location).

VoIPVoIP

SIP ProtocolSIP Protocol INVITEINVITE BYE BYE CANCELCANCEL OPTIONSOPTIONS ACKACK REGISTERREGISTER

VoIPVoIP

H.323 or SIP?H.323 or SIP?

QuestionsQuestions

G.711 PCM A-Law/u-Law G.711 PCM A-Law/u-Law 64 Kbps (DS0)64 Kbps (DS0) G.726 ADPCM G.726 ADPCM 16, 24, 32, 40 Kbps16, 24, 32, 40 Kbps G.727 E-ADPCM G.727 E-ADPCM 16, 24, 32, 40 Kbps16, 24, 32, 40 Kbps G.729 CS-ACELP G.729 CS-ACELP 8 Kbps8 Kbps G.728 LD-CELP G.728 LD-CELP 16 Kbps16 Kbps G.723.1 CELP G.723.1 CELP 6.3/5.3 Kbps Variable6.3/5.3 Kbps Variable

SourcesSources

PCWorldPCWorld http://pcworld.com/article/id,119940-http://pcworld.com/article/id,119940-

page,1/article.htmlpage,1/article.html GNRTGNRT

http://gnrt.terena.nl/content.php?http://gnrt.terena.nl/content.php?section_id=5section_id=5

WikipediaWikipedia http://en.wikipedia.org/wiki/http://en.wikipedia.org/wiki/

Voice_over_IPVoice_over_IP ProgiaProgia

http://www.contentbyexperts.com/http://www.contentbyexperts.com/