Transcript VoIP and IP conferencing over satellites

VoIP and IP conferencing
over satellites
Workshop on VoIP Technology:
Research and Standards for reliable
applications
PIMRC 08, Cannes France
15 September 2008
Dr. Haitham Cruickshank
University of Surrey, UK
Introduction - 1
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Today there is an exponential growth of IP
conversational traffic.
Satellite networks can offer an optimal support
for Multimedia Multiparty Conferencing and IP
Multicasting Services over large geographical
areas.
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The new emerging satellites with multiple spot beams
and On-Board Processing (OBP) will have new
capabilities of dynamically routing information
between various spot beams
However, there is a need to address the
multicast routing, QoS and distribution models
for conferencing media (audio and video) over
satellites
Introduction - 2
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QoS and multicast requirements for IP conferencing were
addressed in an EU project called ICEBERGS (led by
Thales-Alenia Space Italy).
ICEBERGS focused on the efficient configuration intradomain and inter-domain multicast routing. The
architecture consists of the following set of Internet
protocols:
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The intra-domain protocol used here is the Protocol
Independent Multicast-Sparse Mode (PIM-SM): Each domain
uses its own Rendezvous Point (RP) (one or more). A source
located in a given domain registers with an RP of that
domain.
RPs belonging to different domains exchange information
related to the existence of active sources, by means of the
Multicast Source Discovery Protocol (MSDP).
An extension of the classical unicast inter-domain routing
protocol, BGP is used for inter-domain routing: Multiprotocol
Border Gateway Protocol (MBGP). MBGP cooperates with
MSDP in order to provide efficient multicast tree construction
between various domains.
Conferencing media models
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There is a trade off between the large bandwidth
requirements of real-time multimedia conference and
expensive satellite bandwidth cost.
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A hybrid model is used, taking advantage of the
MultiPoint Control Unit (MCU) in H.323 architecture.
MCUs have two main functionalities
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Therefore there is a need for efficient mixing and
distributing conference media (such as audio and video).
Capability to perform audio mixing and video switching on
the video-conference streaming flow
Inter-working between the unicast and multicast IP subset
Another aspect of conferencing is signalling
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Signalling concerns creation, user invitation and
termination of conference sessions.
SIP messages are used by the MCUs to initiate the satellite
connectivity by using RSVP message with the satellite
terminal.
IP conferencing over satellite architecture
QoS implementation in IP
multicast environment
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A hybrid IntServ-DiffServ approach is used for mixed
satellite and terrestrial networks.
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Strict QoS assurances are provided by implementing the
RSVP protocol in the satellite network
whereas in the core portion of the terrestrial Internet
network, where scalability is a stringent requirement, the
scalable DiffServ model is adopted together with
QUASIMODO
The Quality of Service-Aware Multicasting over DiffServ
and Overlay Networks (QUASIMODO) built on top of
existing multicast protocols such as PIM-SM. It includes
two ideas:
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Resource availability along a new QoS path is verified via a
probe-based approach.
QoS is maintained by marking replicated packets with a
special DiffServ Code Point (DSCP) value before forwarding
them on the QoS path.
QoS performance measurement setup
SESAT
RF
Alenia Spazio
Gateway
H320
CODEC
SCPC
Modem
H320
CODEC
SDN
Modem
N
2
1
F-ISP.1
IF
COMBINER
SPLITTER
Conference
server
ESW-P/L-E
CISCO
2500
DESNET
GTW
DES/DCC CONTROLLER
SIP Proxy
Redirect Location
Registar Server
NIU
Edge
Router
F-ISP.2
NIU
Traffic
generator
Core Router
MCU
Designated
Router
Hub
RP
MCU
Traffic
generator
Designated
Router
Border
Router
Hub
Border
Router
Probe
Point B
Core
Network
Border
Router
Designated
Router
Hub
Remote Node
User
User
Traffic
generator
User
Probe
Point A
Measurement
System
F-ISP.3
Quasimodo performance against best
effort delay
One-way-delay
One-way-delay
600
600
QUASIMODO
Best Effort
One-way-delay (msec)
One-way-delay (msec)
500
500
400
400
300
300
200
200
100
100
0
0
0
0
5000
5000
10000
10000
15000
20000
15000
20000
Packet Sequence
Packet Sequence
25000
25000
30000
30000
Conclusions
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A suitable architecture for IP videoconference
system is proposed with IP multicast architecture,
multiple MCUs, QoS provision technique based on
QUASIMODO:
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A multicast solution is proposed to support multiparty
multicast multimedia IP conference over next
generation OBP GEO satellite. This solution consists of
three multicast protocols: PIM-SM, MSDP and MBGP
RSVP is used as a triggering mechanism in the satellite
channel establishment in ICEBERGS. For the
terrestrial part, PIM-SM join message triggers the
QUASIMODO protocol.
The demo results show QUASIMODO provides good
improvement in QoS for IP conferencing in terms of
reduced delay