Transcript NGN 5 - PTCL Training & Development

H.323 Terminals
PTCL Training & Development
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H.323 Terminals
Client end points on the network
IP phones, PCs having own OS
Terminals running an H.323
protocols and the multimedia
applications.
Must support audio G.711 (64
kb/s). Several compression coders
G.723.1, g.729, GSM & others
Should also have support for
Video, data
Support for RTP used for packet
media flow
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H.323 Terminals
Audio
appls
video
appls
G.771
G.729
G.723.1
H261
H263
Terminal Call Manager
RTCP
H225
RAS
H225
Call Sig
H245
Call Cont
T120
Data
RTP
Transport Protocols & Network Interface
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H.323 Gateways
Gateway provides connectivity between an H.323 network
and a non-H.323 network by translating protocols for call
setup and release
Converting media formats between different networks
Transferring information between the networks connected
by the gateway.
A gateway is not required, however, for comn. b/w two
terminals on an H.323 network
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H.323 Gateways
• On the H.323 side, a gateway runs
H.245 control signaling for
exchanging capabilities
• H.245 call signaling for call setup and
release
• H.225 registration, admissions, and
status (RAS) for registration with the
gatekeeper
• On the SCN (switched circuit
network) side, a gateway runs SCNspecific protocols (e.g., ISDN and SS7
protocols)
• Translation between audio, video,
and data formats may also be
performed by the gateway
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H.323 Gateways
Interworking Call Control
Gateway Call Manager
RTP
RTCP
H225
RAS
H225
Call Sign
Transport Protocol & Network Interface
PSTN/ISDN
Signaling
Call control
H245
Control
Sign
PSTN/ISDN
Signaling
Link Control
Physical Interface
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H.323 Gatekeepers
• Considered brain of H.323 network
• It is the focal point for all calls within the
H.323 network
• Provide services such as addressing,
authorization and authentication of
terminals and gateways
• bandwidth management and call-control
services for H.323 endpoints
• An optional feature--Call-signaling
routing. Endpoints send call-signaling
messages to Gatekeeper which are
routed to destination endpoints
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H.323 Gatekeepers
• Gatekeeper provides bandwidth
control by using messages,
bandwidth request (BRQ), confirm
(BCF), and reject (BRJ)
• For instance: A threshold for
simultaneous connections in H.323
network is specified
• Gatekeeper can refuse for any more
connections once the threshold is
reached.
• The result is to limit the total
allocated bandwidth to some
fraction of the total available,
leaving the remaining bandwidth
for data applications.
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H.323 Gatekeepers
Gatekeeper Manager
Billing Services
H225
RAS
H225
Call
Sign
H245
Control
Sign
Directory Services
Security Services
Policy/Call
Mgt. Services
Transport Protocols & Network Interface
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H.323 Multi-point Control
Units
• MCUs provide support for conferences
of three or more H.323 terminals
• All terminals participating in the
conference establish a connection
with the MCU
• MCU manages conference resources,
negotiates between terminals in
determining (CODEC) to use
• Handle the media stream
• Gatekeepers, Gateways, and MCUs are
logically separate components of the
H.323 standard but can be
implemented as a single physical
device
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H.323 Multi-point Control Units
• MCU has two Logical entities:
Multipoint Controller
Multipoint Processor
• Multipoint Controller: Controls conference call for a
Multicast(many users) or Unicast (to single user)
• Multipoint Processor: provides advanced functions in H323
like video mixing, audio mixing or video switching
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