H'323 Multimedia over IP Technology Overview

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H.323 - Multimedia over IPTechnology Overview
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What is H.323?

• An ITU standard for interoperability
• Works over existing infrastructures
• (LAN/WAN, Internet, ISDN, POTS)

• Can be deployed wherever IP is used
• Ethernet, Token Ring, FDDI,
• Frame Relay (RFC1490), ATM etc

• Supports Multimedia Applications
• Data (and data conferencing)
• Audio (typically packetised speech)
• Video

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H.323 Network Components
H.320 Endpoint
ISDN
Switched Circuit Network(s)
H.324 Endpoint
POTS
POTS
Analogue Telephone
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The H.323 Endpoint

• H.323 Mandatory Requirements
• G.711 (PCM audio codec, 64Kbps)
• H.245 (for identifying and controlling media
  exchanges, such as
• voice and video)
• Q.931 (a signaling protocol for establishing and
  releasing
• connections)
• Registration/Admission/Status (RAS) Channel A
  data stream used
• to communicate with a Gatekeeper
  (RAS only needed if a
• Gatekeeper exists within the
  endpoint zone)
• Real-Time Protocol/ Real-Time Control Protocol
  (RTP/RTCP)
• IETF application level protocol for
  transporting real-time
• media on IP networks

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ITU Recommendations - H.32X
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H.323 Environment
H.323 Terminal
Gateway
Gatekeeper
Multipoint Control Unit
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H.323 Terminals (Endpoints)

• Audio
• Video
• Data
• Control

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Gateway Functions
Intranet/Extranet
PSTN
Gateway
P B X

• Portal between Switched Circuit Network (e.g.
  PSTN) and Intranet/Extranet

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Gatekeeper Functions
Gateway
Gatekeeper
MCU

• May perform call control functions
• for terminals/gateways in an area/zone

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H.323 Protocol Stack
Control
Audio
Video
Data
T.12X
RAS Q.931 H.245
G.723.1 G.729 G.729A
H.261 H.263
RTP/ RTCP
RTP/ RTCP
TCP
UDP
IP
LAN
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H.323 Call Procedures
Audio/ Video Codecs
Packet Processing
RTP/ RTCP
UDP
IP
Audio/Video Streams Module
RAS (if GK present)
Call Signaling - Q.931 (if GK present)
TCP
Control Channel - H.245
System Control Unit
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RAS
Endpoint
Gatekeeper
RAS

• Registration, Admission, and Status

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RAS Support - With and Without GK
With Gatekeeper
Without Gatekeeper
RAS
RAS
No RAS
No RAS
6400 Gateway
6400 Gateway
PSTN
PSTN
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Call Signaling Channel - Q.931
RAS
Call Signaling
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Q.931 Call Signaling - With GK
With Gatekeeper
RAS
RAS
Call Signaling
6400 Gateway
PSTN
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Q.931 Call Signaling -Without GK
Without Gatekeeper
Call Signaling
6400 Gateway
PSTN
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Basic Call Setup (Direct Endpoint)
Call Signaling
Setup
Call Proceeding
Alerting
Connect
Q.931
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Basic Call SetupWith Gatekeeper
Gatekeeper
RAS
RAS
Call Signaling
ARQ
ACF
Setup
Q.931
Call Proceeding
ARQ
ACF
Alerting
Connect
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Basic Call SetupWith Gatekeeper
Gatekeeper
RAS
RAS
Call Signaling
ARQ
ACF
Setup
Setup
Call Proceeding
Q.931
Call Proceeding
ARQ
ACF
Alerting
Alerting
Connect
Connect
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H.245 Control Channel
RAS
Control Channel
Call Signaling
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H.245 Control Channel With GK
Gatekeeper
RAS
RAS
Control Channel
6400 Gateway
PSTN
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H.245 Control ChannelWithout GK
Without Gatekeeper
Control Channel
6400 Gateway
PSTN
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Audio
G.723.1/G.729
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Video
H.261/H.263
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T.120 Data Conferencing
File Transfer
Shared Whiteboarding

• Provides support for real-time multipoint data
  communications

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Audio and Video Synchronization

• RTP and RTCP

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Quality of Service (QOS)
Say again, youre breaking up..
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Resource Reservation Protocol (RSVP)
Router
Router with reserved capacity for RSVP flow
RSVP request level of service

• Bandwidth reservation done on a link-by-link
  basis
• All routers in path must support RSVP
• Problems of scalability

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Differentiated Services

• Traffic forwarding priority determined by IPv4
  TOS bits
• (6 bits used as Differentiated Service bits)
• TOS set at edge of the network
• Transit nodes interrogate TOS and forward
  packets
• accordingly

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Multipoint Control Unit (MCU)
Can yall hear me?
MCU

• Facilitates Desktop Conferencing

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Multipoint Control Unit
M C
M P
Can yall hear me?
MCU
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Centralized Conferencing
Can yall hear me?
MCU
Conference Control Audio/Video Streams Unicast
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Decentralized Conferencing
MCU
Conference Control Unicast
Can yall hear me?
Audio/Video Streams Multicast
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H.323 version 2

• Address deficiencies in version 1
• Adds functionality to existing protocols
• Security
• Fast call setup
• Supplemental services
• Clarifies T.120/H.323 integration
• and more..

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ETSI PROJECT TIPHON

• Telecommunications and Internet Protocol
  Harmonization over Networks

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WWW Background Resources

• www.data.com/Tutorials/Multimedia_Over_IP
• www.data.com/roundups/decision
• www.data.com/roundups/ip_telephony
• www.data.com/roundups/rsvp
• www.databeam.com/h323/h323primer
• www.databeam.com/ccts/t120primer
• www.pcwebopedia.com/Internet_telephony