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A Presentation on H.323

A Presentation on H.323. Deepak Bote. Email, IM, blog…. Important events of 1996!!. Bill Clinton was re-elected. Dolly, the cloned sheep, was born. Prince Charles and Diana were divorced… Emergence of VoIP & Internet Telephony. We are interested in the last one!. What about H.323???.

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A Presentation on H.323

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  1. A Presentation on H.323 Deepak Bote

  2. Email, IM, blog…

  3. Important events of 1996!! • Bill Clinton was re-elected. • Dolly, the cloned sheep, was born. • Prince Charles and Diana were divorced… • Emergence of VoIP & Internet Telephony We are interested in the last one!

  4. What about H.323??? • VoIP products were proprietary. • Hence incompatible. • A standard for interoperability • H.323 v1 was already existing for LANs. • V2 was developed to solve the incompatibility issue.

  5. What exactly is H.323? • Standard recommended by ITU-T • Defines real-time MM communications over packet based networks. • Collection of Standards. • H.323 belongs to the H.32x class of standards for videoconferencing applications.

  6. H.323 – A Closer Look E N D P O I N T S • Terminals (what people see/hear) • Gateways (control and ‘routing’ ) • Multipoint Control Units (provides conference capabilities ) • Gatekeepers (access to other environments)

  7. Terminals • H.323 client endpoints • They could be: • Multimedia PCs • Any stand-alone device • A simple telephone • Expectation by H.323: • Must support audio communication. • Video, data support optional

  8. Gateways • Optional Component of H.323 implementation. • Used as interface between different networks e.g. LAN & PSTN • Functions: • Data format translation • Audio/video codec translation • Call setup, termination from both sides of the network

  9. Multipoint Control Units • MCUs are also optional in a H.323 implementation • Needed only when multiparty conferences are desired • Functions: • Provides capability of video-conferencing with more than one party. • Acts as a co-ordinator of multiparty conferences

  10. Gatekeepers • “Brains” of a H.323 network • Expectation by H.323: • Address translation • Admissions Control • Bandwidth Control • Zone Management • Routing Capabilities

  11. Gatekeeper Zones The Internet Zone B Gateway Gatekeeper Zone A Gatekeeper

  12. Router Gateway Phone MCU Gatekeeper Gateway ISDN videophone H.323 terminal H.323 terminal

  13. The Protocols!!

  14. The Protocols (cont) • H.323 recommendation is a “framework” document that describes how the various pieces fit together • H.225.0 defines the call signaling between endpoints and the Gatekeeper • RTP/RTCP (RFC 3550) is used to transmit media such as audio and video over IP networks • H.225.0 define the procedures and protocol for communication within and between Peer Elements • H.245 is the protocol used to control establishment and closure of media channels within the context of a call and to perform conference control

  15. The Protocols (cont) • H.450.x is a series of supplementary service protocols • H.460.x is a series of version-independent extensions to the base H.323 protocol • T.120 specifies how to do data conferencing • T.38 defines how to relay fax signals • V.150.1 defines how to relay modem signals • H.235 defines security within H.323 systems

  16. The Protocols (cont) • Audio: • G.711 (popular codec for telephone n/ws) • G.723.1 – more efficient • Video • H.261 codec (for channels with bandwidths p*64 kb/s) • H.263 codec (for low bit rate transmission without loss of quality )

  17. Typical H.323 Stack H.323 Multimedia Applications, User Interface Data Applications Media Control Terminal Control and Management H.225.0 Call Signaling H.245 V.150 T.120 T.38 RTCP H.225.0 RAS Audio Codecs G.711 G.723.1 G.729 .. Video Codecs H.261 H.263 H.264 .. RTP UDP TCP TCP/UDP UDP TCP/UDP TCP UDP IP

  18. An H.323 Stack H.323 Application RAS H.245 RTP / RTCP H.225.0 Call Signaling Packet Network

  19. H.323 Call Setup and Tear Down

  20. Future • Users want mobility - “Internet Phone Numbers” that follow them anywhere • Enhancements for billing • Enhancements to fax • More interoperability

  21. Concluding Remarks • H.323 is a protocol that leverages the strength of the packet-switched protocols from the IETF • H.323 offers excellent integration with the PSTN • H.323 enables voice, video, and data conferencing • H.323 provides a solid foundation for new services and the continued growth of Multimedia over IP

  22. References • www.h323forum.org • http://www.packetizer.com/voip/h323/ • Intel Tutorial site

  23. Thank You

  24. Registration, Admission, and Status - RAS • Defined in H.225.0 • Allows an endpoint to request authorization to place or accept a call • Allows a Gatekeeper to control access to and from devices under its control • Allows a Gatekeeper to communicate the address of other endpoints • Allows two Gatekeepers to easily exchange addressing information

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