1 / 28

H.323 Packet-based multimedia communications systems

Explore the structure and elements of H.323 protocol stack and delve into call signaling procedures for efficient multimedia communications systems. Learn about terminals, gateways, gatekeepers, and multipoint control units. Understand phases of call setup, communication establishment, service provision, and termination in this comprehensive outline.

lbattaglia
Download Presentation

H.323 Packet-based multimedia communications systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. H.323 Packet-based multimedia communications systems Speaker: Yi-Lei Chang Advisor: Dr. Kai-Wei Ke 2012/11/28

  2. Outline • Introduction • Protocol Stack • Elements • Call signalling procedures

  3. Introduction • 1996 • ITU-T (Telecommunication Standardization sector of International Telecommunication Union) • Packet-based multimedia communications systems

  4. Protocol Stack

  5. Additional Documents • H.235 Security within H.245-based systems • H.450.x Supplementary services • H.460.x Various H.323 protocol extensions • H.501 Protocol for mobility management and inter/intra-domain communication • H.510 User, terminal, and service mobility • H.530 Security specification for H.510

  6. Elements • Terminals • Gateways • Gatekeeper • MC, MP, MCU • Multipoint controller • Multipoint processor • Multipoint control unit

  7. Terminals • Telephones, Video phones, etc. • Soft phones • G.711 (voice) • H.261 (video, optional)

  8. Gateway • Interface H.323 to other networks • PSTN • H.320 systems • other H.323 networks (proxy) • etc.

  9. Gatekeeper • Optional element • H.225.0 RAS • Address Translation • Admissions Control • Bandwidth Control • Zone Management • Optional • Call Control signalling • Call Management

  10. MC, MP, MCU • Multipoint controller • Provides control functions to support conferences between three or more endpoints in a multipoint conference • Multipoint processor • Handle media mixing, switching, or other media processing • Multipoint control unit • An endpoint which provides support for multipoint conferences • The MCU shall consist of an MC and zero or more MPs

  11. MC, MP, MCU

  12. H.255.0 RAS • Registration, Admission, and Status • Used between the endpoint and its Gatekeeper • RAS Port • 1719 (unicast) • 1718 (multicast) for GRQ, LRQ • RAS messages generally have three types • Request (xRQ) • Reject (xRJ) • Confirm (xCF) • x can be • G:GatekeeperR:Registration • A:AdmissionsL:Location • D:DisengageU:Unregistration • IRQ (Information Request), IRR (Information Request Response)

  13. Call signalling procedures • Phase A: Call setup. • H.225.0/Q.931 Call control , H.225.0 RAS (if reg. to a gatekeeper) • Phase B: Initial communication and capability exchange • H.245 Multimedia control, H.225.0/Q.931 Call control • Phase C: Establishment of audiovisual communication • H.245 Multimedia control, RTP, RTCP • Phase D: Call services • Status, Bandwidth changes, Conference expansion • Phase E: Call termination • H.225.0/Q.931 Call control, H.245 Multimedia control (optional), H.225.0 RAS (if reg. to a gatekeeper)

  14. Phase A: Call setup • Notify user, setup H.245 channel • Caller/Callee registered to Gatekeeper? • Routed/direct call? (if reg. to a Gatekeeper) • Simple call setup:

  15. Phase A: Call setupCaller/Callee registered to Gatekeeper

  16. Phase A: Call setupCaller routed call

  17. Phase A: Call setupCallee routed call

  18. Phase A: Call setupAn example • Endpoint 1 • registered to gatekeeper 1 • Gatekeeper 1 • use direct call • Endpoint 2 • registered to gatekeeper 2 • Gatekeeper 2 • use routed call

  19. Phase B: Initial communication and capability exchange • Capability exchange • Master Slave Determination

  20. Phase C: Establishment of audiovisual communication

  21. Phase D: Call services • Status • IRQ, IIR • Interval > 10 sec. • Bandwidth changes • BRQ, BCF, BRJ • closeLogicalChannel, openLogicalChannel, flowControlCommand • Conference expansion • Create • Invite • Join

  22. Phase E: Call termination • Terminate a call • Discontinue transmission of video, data, audio and then close all logical channels for them • Transmit the H.245 endSessionCommand (optional) • Close H.245 Control Channel • Transmit a Release Complete message and close the H.225.0 call signalling channel • Terminate a conference • H.245 message dropConference • Wait for MC to terminate calls • Call clearing with a gatekeeper • Call clearing by gatekeeper

  23. Phase E: Call terminationCall clearing with a gatekeeper

  24. Phase E: Call terminationCall clearing by gatekeeper

  25. Reference [1] International Telecommunication Union, "Packet-based Multimedia Communications Systems," Recommendation H.323, Telecommunication Standardization Sector of ITU, December 2009. [2] International Telecommunication Union, "Call signalling protocols and media stream packetization for packet-based multimedia communication systems," Recommendation H.225.0, Telecommunication Standardization Sector of ITU, December 2009. [3] International Telecommunication Union, "Control protocol for multimedia communication," Recommendation H.245, Telecommunication Standardization Sector of ITU, May 2011.

  26. Thanks for Listening Q&A

More Related