Post on 11-Feb-2016
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A Presentation on H.323A Presentation on H.323
Deepak BoteDeepak Bote
Email, IM, blog…Email, IM, blog…
Important events of 1996!!Important events of 1996!!
Bill Clinton was re-elected.Bill Clinton was re-elected.
Dolly, the cloned sheep, Dolly, the cloned sheep, was born.was born.
Prince Charles and Diana were divorced…Prince Charles and Diana were divorced… Emergence of VoIP & Internet TelephonyEmergence of VoIP & Internet Telephony
We are interested in the last one!
What about H.323???What about H.323???
VoIP products were proprietary.VoIP products were proprietary. Hence incompatible.Hence incompatible. A standard for interoperabilityA standard for interoperability H.323 v1 was already existing for H.323 v1 was already existing for
LANs.LANs. V2 was developed to solve the V2 was developed to solve the
incompatibility issue.incompatibility issue.
What exactly is H.323?What exactly is H.323?
Standard recommended by ITU-TStandard recommended by ITU-T Defines real-time MM communications over Defines real-time MM communications over
packet based networks.packet based networks. Collection of Standards.Collection of Standards. H.323 belongs to the H.32x class of standards H.323 belongs to the H.32x class of standards
for videoconferencing applications.for videoconferencing applications.
H.323 – A Closer LookH.323 – A Closer Look Terminals (what people see/hear)Terminals (what people see/hear)
Gateways (control and ‘routing’ )Gateways (control and ‘routing’ )
Multipoint Control Units (provides Multipoint Control Units (provides conference capabilities )conference capabilities )
Gatekeepers (access to other Gatekeepers (access to other environments) environments)
E
N
D
P
O
I
N
T
S
TerminalsTerminals
H.323 client endpointsH.323 client endpoints They could be:They could be:
Multimedia PCsMultimedia PCs Any stand-alone deviceAny stand-alone device A simple telephoneA simple telephone
Expectation by H.323:Expectation by H.323: Must support audio communication.Must support audio communication. Video, data support optionalVideo, data support optional
GatewaysGateways Optional Component of H.323 Optional Component of H.323
implementation.implementation. Used as interface between different Used as interface between different
networks networks e.g. LAN & PSTNe.g. LAN & PSTN
Functions:Functions: Data format translationData format translation Audio/video codec translationAudio/video codec translation Call setup, termination from both sides of the Call setup, termination from both sides of the
networknetwork
Multipoint Control UnitsMultipoint Control Units
MCUs are also optional in a H.323 MCUs are also optional in a H.323 implementationimplementation
Needed only when multiparty conferences are Needed only when multiparty conferences are desireddesired
Functions:Functions: Provides capability of video-conferencing with more Provides capability of video-conferencing with more
than one party.than one party. Acts as a co-ordinator of multiparty conferencesActs as a co-ordinator of multiparty conferences
GatekeepersGatekeepers
““Brains” of a H.323 networkBrains” of a H.323 network Expectation by H.323:Expectation by H.323:
Address translationAddress translation Admissions ControlAdmissions Control Bandwidth ControlBandwidth Control Zone ManagementZone Management Routing CapabilitiesRouting Capabilities
Gatekeeper
Gatekeeper
Gateway
Zone B
Zone A
The Internet
Gatekeeper ZonesGatekeeper Zones
Router
H.323 terminal H.323 terminal ISDN videophone
Gateway
Gateway Phone
MCUGatekeeper
The Protocols!!The Protocols!!
The Protocols (cont)The Protocols (cont) H.323 recommendation is a “framework” document that H.323 recommendation is a “framework” document that
describes how the various pieces fit togetherdescribes how the various pieces fit together H.225.0 defines the call signaling between endpoints and H.225.0 defines the call signaling between endpoints and
the Gatekeeperthe Gatekeeper RTP/RTCP (RFC 3550) is used to transmit media such as RTP/RTCP (RFC 3550) is used to transmit media such as
audio and video over IP networksaudio and video over IP networks H.225.0 define the procedures and protocol for H.225.0 define the procedures and protocol for
communication within and between Peer Elementscommunication within and between Peer Elements H.245 is the protocol used to control establishment and H.245 is the protocol used to control establishment and
closure of media channels within the context of a call and to closure of media channels within the context of a call and to perform conference controlperform conference control
The Protocols (cont)The Protocols (cont) H.450.x is a series of supplementary service H.450.x is a series of supplementary service
protocolsprotocols H.460.x is a series of version-independent H.460.x is a series of version-independent
extensions to the base H.323 protocolextensions to the base H.323 protocol T.120 specifies how to do data conferencingT.120 specifies how to do data conferencing T.38 defines how to relay fax signalsT.38 defines how to relay fax signals V.150.1 defines how to relay modem signalsV.150.1 defines how to relay modem signals H.235 defines security within H.323 systemsH.235 defines security within H.323 systems
Audio: Audio: G.711 (popular codec for telephone n/ws)G.711 (popular codec for telephone n/ws) G.723.1 – more efficientG.723.1 – more efficient
VideoVideo H.261 codec (for channels with bandwidths H.261 codec (for channels with bandwidths
p*64 kb/s)p*64 kb/s) H.263 codec (for low bit rate transmission H.263 codec (for low bit rate transmission
without loss of quality )without loss of quality )
The Protocols (cont)The Protocols (cont)
Typical H.323 StackTypical H.323 Stack
H.323
IP
UDP
RTP
RTCP
TCP/UDP TCP UDPUDP TCP
AudioCodecsG.711
G.723.1G.729
..
VideoCodecsH.261H.263H.264
..V.150 T.120
TCP/UDP
T.38H.225.0
CallSignaling
H.245 H.225.0RAS
Terminal Control and ManagementDataApplications Media Control
Multimedia Applications, User Interface
An H.323 StackAn H.323 Stack
RAS RTP / RTCP
Packet Network
H.323 Application
H.245
H.225.0Call Signaling
H.323 Call Setup and Tear Down
FutureFuture
Users want mobility - Users want mobility - “Internet Phone “Internet Phone Numbers” that follow them anywhereNumbers” that follow them anywhere
Enhancements for billingEnhancements for billing Enhancements to faxEnhancements to fax More interoperabilityMore interoperability
Concluding RemarksConcluding Remarks H.323 is a protocol that leverages the strength of H.323 is a protocol that leverages the strength of
the packet-switched protocols from the IETFthe packet-switched protocols from the IETF H.323 offers excellent integration with the PSTNH.323 offers excellent integration with the PSTN H.323 enables voice, video, H.323 enables voice, video, and and data conferencingdata conferencing H.323 provides a solid foundation for new H.323 provides a solid foundation for new
services and the continued growth of Multimedia services and the continued growth of Multimedia over IPover IP
ReferencesReferences
www.h323forum.orgwww.h323forum.org http://www.packetizer.com/voip/h323/http://www.packetizer.com/voip/h323/ Intel Tutorial siteIntel Tutorial site
Registration, Admission, and Registration, Admission, and Status - RASStatus - RAS Defined in H.225.0Defined in H.225.0 Allows an endpoint to request authorization Allows an endpoint to request authorization
to place or accept a callto place or accept a call Allows a Gatekeeper to control access to Allows a Gatekeeper to control access to
and from devices under its controland from devices under its control Allows a Gatekeeper to communicate the Allows a Gatekeeper to communicate the
address of other endpointsaddress of other endpoints Allows two Gatekeepers to easily exchange Allows two Gatekeepers to easily exchange
addressing informationaddressing information