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INFOTECH Seminar Advanced Communication Services (ACS), 2005 Mentor: Dr.-Ing. Stephan Rupp. SIP based VoIP service Architecture and Comparison. Student: TONG Hoang Anh Institute of Communication Networks and Computer Engineering University of Stuttgart. General model for VoIP.
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INFOTECH Seminar Advanced Communication Services (ACS), 2005 Mentor: Dr.-Ing. Stephan Rupp SIP based VoIP service Architecture and Comparison Student: TONG Hoang Anh Institute of Communication Networks and Computer Engineering University of Stuttgart
Motivation • Voice over IP expected to replace the Public Switched Telephone Network (PSTN) • Challenges: • provide new, attractive multimedia service • control of advanced features(supplementary services) SIP and H323 are 2 approaches
Agenda • SIP • SIP architecture • SIP messages • Scenarios • H323 • H323 architecture • Scenarios • Comparison and conclusion
SIP architecture Accept REGISTER request from client Forward message to next hop server UAC:initiate SIP request UAS:return SIP respond Redirect caller to destination or other server
SIP messages • INVITE : invites a user to join a call. • ACK : confirms of the received response to an INVITE. • BYE : terminates the call between two of the users on a call. • OPTIONS : requests information on the capabilities of a server. • CANCEL : ends a pending request, but does not end the call. • REGISTER : informs a server the location of a user.
Simplest peer-to-peer call setup INVITE OK, 200 ACK Media session BYE OK, 200 Bob Alice
SIP operation in Proxy mode Location server #8 #6 #5 #4 #3 #1 #2 #7 Alice alice@195.37.78.193 INVITEsip:alice@iptel.org From: bob@sip.com To: alice@iptel.org Call-ID: 345678@sip.com INVITEsip:alice@195.37.78.193 From: bob@sip.com To: alice@iptel.org Call-ID: 345678@sip.com Alice Alice@iptel.org Bob Bob@sip.com OK 200 From: bob@sip.com To: alice@iptel.org Call-ID: 345678@sip.com OK 200 From: bob@sip.com To: alice@iptel.org Call-ID: 345678@sip.com Proxy server ACKsip:alice@iptel.org Media stream Media stream
SIP operation in Redirect mode Location server #8 #7 #6 #5 #3 #4 #1 #2 #9 Alice alice@home.com INVITEalice@iptel.org Alice Alice@iptel.org Bob Bob@sip.com Redirect server 302 moved temporarily Contact: alice@home.com Media stream ACKalice@iptel.org INVITEalice@iptel.org OK 200 ACKalice@home.com
Agenda • SIP • SIP architecture • SIP messages • Scenarios • H323 • H323 architecture • Scenarios • Comparison and conclusion
H323 architeture Address Translation, Admissions Control, Bandwidth Control, Zone Management Enable conferencing MC: multipoint call and control signalling MP: mixing, switching, and processing of the audio, video, and data streams H323 endpoint, originate and terminate H323 signalling and data stream (must support audio) Data format translation, control signaling translation, audio/video, codec translation, call setup/termination functionality
H323 call establishment Bob Alice ARQ(1) ACF/ARJ(6) ACF/ARJ(2) CALL PROCEEDING(4) ALERTING(7) CONNECT(8) SETUP(3) ARQ(5)
H323 call control signalling Bob Alice TerminalCapabilitySet(9) TerminalCapabilitySetAck(10) TerminalCapabilitySet(11) TerminalCapabilitySetAck(12) OpenLogicalChannel(13) OpenLogicalChannelAck(14) OpenLogicalChannel(15) OpenLogicalChannelAck(16)
Media stream and Media control flow Bob Alice RTP Media Stream(17) RTP Media Stream(18) RTCP Message (19) RTCP Message (20)
H323 Call release Bob Alice EndSessionCommand (22) DCF (25) DCF(25) EndSessionCommand (21) DRQ (24) DRQ (24) RealeaseComplete (23)
Agenda • SIP • SIP architecture • SIP messages • Scenarios • H323 • H323 architecture • Scenarios • Comparison and conclusion
H323 vs SIP : Comparison Network components Protocols running on terminal
Conclusion • H323 is a comprehensive set of protocols,focus on handling voice and multimedia calls including supplementary services. • SIP is a generic transaction protocol for session initiation, not limited to any specific media services. • H.323 provides better functionality, interoperability and interworking (with PSTN) with respect to supplementary services. • SIP has its strengths for lightweight and easy-implemented solutions with focus on flexible session initiation.SIP provides better mechanisms for controlling non-VoIP services. • Two standards are approaching each other. • In the public VoIP services, SIP is currently the dominent technology.