• • • • • • • • • What is H.323 Scope of H.323 Why is H.323 Important Historical Development Stages Elements of H.323 System H.323 Network Architecture H.323 Core Protocols H.323: Call Signaling Prospect/Future of H.323 2 Que es H.323 H.323* is a multimedia conferencing protocol, which includes voice, video and data conferencing for use over packet-switched networks Real-time multimedia communications and conferencing for packet-based networks 3 Tr e n d Porque es Importante H.323 R a p i d growth of the Internet Universal deployment of corporate Standardization H.323 is a standard protocol has been widely accepted 4 Historia del Protocolo • H.323v1 published designed for LAN – Companies tried to do use H.323 in WAN, large private VoIP networks, and the Internet • • 5 Arquitectura Alternate Gatekeepers B y using Alternate Gatekeepers, endpoints are able to continue functioning in the face of one or more failures Never Lose a Call! GK GK GK GK X X T 6 Components of H.323 System Terminals w h a t people see/hear Multipoint Control Units (MCUs) provides conference capabilities Gateways c o n t r o l and ‘routing’ Gatekeeper access to other environments B o r d e r Elements 7 Terminales A n endpoint on the network which provides for real-time, two-way communication with other H.323 terminal, GW, or MCU Te r mi n al can be: Telephones Vi d e o phones I V R devices Voicemail Systems T 8 Multipoint Control Units (MCUs) Needed o n l y when multiparty conferences are desired Functions: T o manages call signaling Provides capability of videoconferencing with more than one party A c t s as a coordinator 9 Gateways (GW) • Gateway (GW) • used as interface H.323 between different networks e.g. LAN & PSTN • Functions: • Data format translation • Audio/video codec translation • Call setup, termination from both sides of the network 10 Gatekeeper (GK) Gatekeeper is an optional component in H.323 system used for: Admission Control and Address Resolution E n d p o ints do register themselves at a Gatekeeper A l l H.323 endpoints registered to a single GK build an H.323 zone H .3 2 3 zones are independent of physical network topology 11 Gatekeeper Functionality Mandatory Gatekeeper Functions Address Translation Admission Control Bandwidth Control Z o n e Management O p t i o n a l Gatekeeper Functions Call-Control Signaling C a l l Authorization Bandwidth Management C a l l Management 12 Gatekeeper Zone s The Internet Zone B Gateway Gatekeeper Zone A Gatekeeper 13 Border Elements (BE) Co-located with Gatekeeper, Exchange addressing information Participate in call authorization between administrative domains M a y aggregate address information to reduce the volume of routing information passed through the network M a y assist in call authorization/authentication directly between two administrative domains or via a clearinghouse 14 Using Elements (BE) As with hierarchical GK/BE LRQ Gatekeepers, Border Elements may send Access Request messages to other Border Elements and indicate where to send a reply Border Elements may also ARQ GK T GK/BE reply directly to a request by utilizing address information cached from previous exchanges with other Border Elements 16 Router Gateway Phone MCU Gatekeeper Gateway H.323 terminal H.323 terminal ISDN videophone 17 Protocols of H.323 H.323 is an umbrella of four protocols: • Registration Admission and Status (RAS) – define communications between endpoints and gatekeeper – only needed when a gatekeeper exists • H.245 - Connection Control • for Capability Negotiations H.225/Q.931- Call Signaling (between endpoint and gatekeeper, or between gatekeepers) • Real-time Transport Protocol(RTP) - timely and orderly delivery of audio and video streams 18 H.323 Protocol 19 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 20 Registration Admission and Status (con) T RRQ RCF GK (endpoint is registered) ARQ ACF (endpoint may place call) DRQ (call has terminated) DCF 21 H.225 H . 2 2 5 Call Signaling H.225 call signaling is used to establish a connection between two H.323 endpoints Achieved by exchanging H.225 protocol messages onthe callsignaling channel call-signaling channel is opened between two H.323 endpoints or between an endpoint and gatekeeper H . 2 2 5 is the conference control protocol Master/slave determination Capability exchange Management of media and data streams 22 RTP/RTCP R e a l Time Transport Protocol (RTP) end-to-end network transport function payload type, sequence number, timestamp RT P Control Protocol (RTCP) quality feedback, RTP session control 34 CODECs Audio G.711 (popular codec for telephone n/ws) G.723.1 – more efficient Vi d e o H.261 codec (for channels with bandwidths p*64 kb/s) H .2 6 3 codec (for low bit rate transmission without loss of quality ) 24 Voice over IP: Protocols Vo i c e over IP has been implemented in various ways using both proprietary and open protocols and standards. Examples of the network protocols used to implement VoIP include: H.323 Media Gateway Control Protocol (MGCP) Session Initiation Protocol (SIP) Real-time Transport Protocol (RTP) Session Description Protocol 25 Voice over IP: Business use 26 H.323 vs. SIP 27 H.323 vs. SIP 28 H.323 vs. SIP 29 H.323 vs. SIP 30 H.323: Network Architecture GK MCU GK MCU WAN LAN1 TE GW Zone-1 LAN2 GW TE Zone-2 Simple Network Architecture of H.323 31 H.323 Protocol Architecture Control Data signal + connection Q.93 1 /H.22 5 H.24 5 T.12 0 Audio Video G.7x x H.26 x AV Control RTCP GK Control RAS RTP TCP UDP IP Protocol Relationships in H.323 32 H.323: Call signaling H.323 Call signal goes through 7 Phases: Pro to co l Phase • • • Call admission Call RAS set-up Q.931 Capability negotiation H.245 • Stable call RTP • Channel closing H.245 • Call tear-down Q.931 • Call disengage RAS 33 H.323 Call Signaling Model • Direct Call Model - Gatekeeper optional • Gatekeeper Routed Call Model 34 Direct Call Model Gatekeeper Cloud optional Q.931 Terminal Endpoint 1 H.245 RTP Terminal Endpoint 2 35 Gatekeeper Routed Call Model Gatekeeper Cloud Terminal Endpoint 1 RTP Terminal Endpoint 2 36 Call set-up with Gatekeeper Routing t 37 Security Issue in H.323 in H.323 v1 H .2 3 5 Security protocols ITU authentication: end-point authentication integrity: validation within a packet privacy: encryption and decryption mechanism non-repudiation: false denial of participation 38 Call Enhancement in H.323 H.323 v2 & v3 H.450 on top of Q.931 1. – Generic functional protocols and procedures [v1] 2. – Call Transfer [v2] 3. – Call Diversion 4. – Call Hold 5. – Call Park and Pick-up [v3] 6. – Message Waiting indication 7. – Call Waiting 8. – Name Identification[v4] 9. – Call Completion 10. – Call Offer 11. – Call Intrusion and so on… 39 H.323: Market Today To d a y the biggest market for H.323 applications si Voice over IP. Why? L o w bit-rate Internet connections make video and dat intensive applications less appealing I t ’s a young industry– and with all such industries, it takes time to mature good products Companies can provide VoIP services today at a low cost and provide new competition to the incumbent carriers 40 H.323: Beyond Voice over IP Vo i c e over IP opens the door to the next generation of communication products I t will take some time to migrate the world from PSTN to IP networks H.323 provides excellent interworking between IP networks and the PSTN H.323 provides a strong foundation for new multimedia products and services 41 H.323: IP Telephony • IP Telephony with H.323 truly means Multimedia over IP • IP Telephony is not Just Research TopicAnymore – is now real… there are many deployed products and services that offer IP Telephony services – new kinds of services are now available to customers using IP Telephony that were never possible before 42 H.323: Makes All Possible H.3 23 makes it possible to create and deploy n ew services quickly and to take advantage of multimedia capabilities T h e s e services can embrace audio, video, and data conferencing - Application Sharing - Electronic Whiteboard - File Transfer - Instant Messaging - Click to Dial - Internet Call Waiting - Web Call Parking - Call No-Waiting - Ad-Hoc Conferencing - Voicemail Anywhere - Unified Messaging - Service Portability - Services! - Services! - Services! 43 H.323: for Service Provider H.3 23 is a proven technology that is utilized in large networks, such as Genuity, iBasis, ITXC, China Unicom, and others Excellent integration with the PSTN Gateways and residential devices are in use today 44 H.323: in the Enterprise Multimedia conferencing devices show the real potential of H.323 and multimedia communication W i t h H.323 in the service provider network, H.323 si a logical choice for the enterprise T h e enterprise customer wants voice, video, and data conferencing capabilities 45 Importance of H.323 Interoperability - H.323 establishes methods for receiving clients to communicate capabilities to the sender N e t w o r k independence - H.323 is not tied to an yhardware or operating system H.323 sets multimedia standards for the existing infrastructure (i.e. IP-based networks) H.323 conference can include endpoints with different capabilities H.323 provides multiple audio and video CODECs that format data according to the requirements of various networks, using different bit rates, delays, and quality options. 46 Importance of H.323 (con) A l t h o ug h H.323 can support conferences of three or more endpoints without requiring a specialized multipoint control unit, MCU's provide a more powerful and flexible architecture for hosting multipoint conferences A l t h o ug h H.323 can support conferences of three or more endpoints without requiring a specialized multipoint control unit, MCU's provide a more powerful and flexible architecture for hosting multipoint conferences H.323 supports multicast transport in multipoint conferences H.323 has the support of many computing and communications companies and organizations 47 H.323: Pros and Cons 48 Acronyms • • • • • • • • • • • • • • • • ARQ –Admission Request message BE – Border Element GEF – Generic Extensibility Framework GK – Gatekeeper GW – Gateway IETF – Internet Engineering Task Force IMTC – International Multimedia Telecommunications Consortium IP – Internet Protocol IVR – Interactive Voice Response LAN – Local Area Network LRQ – H.225.0 Location Request message MCU – Multipoint Control UnitMC – Multipoint Controller MG – Media Gateway MGC – Media Gateway Controller MP – Multipoint Processor PSTN – Public Switched Telephone Network 49 Acronyms • • • • • • • • • • • • • • • • • • • RFC – Request for Comments RTP – Real-Time Transport Protocol RTCP – Real-time Transport Control Protocol TCS – H.245 Terminal Capability Set message UDP – User Datagram Protocol URL – Uniform Resource Locator VoIP – Voice over IP MC – Multipoint Controller MG – Media Gateway MGC – Media Gateway Controller MP – Multipoint Processor PSTN – Public Switched Telephone Network RFC – Request for Comments RTP – Real-Time Transport Protocol RTCP – Real-time Transport Control Protocol TCS – H.245 Terminal Capability Set message UDP – User Datagram Protocol URL – Uniform Resource Locator VoIP – Voice over IP 50 Questions ? T h a n k Yo u for Kind Attention 51
