Transcript Voice over Packet - Part 5

V
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VoX
What is X ?
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VoFR – why?
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FR is the most mature of PSNs
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many enterprises already have FR network
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convergence: infrastructure, management
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FR can be global
price not dependent on distance
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typically pay for committed rate
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so get VoFR for free !
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VoFR – how?
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Frame Relay
FRAD
Data Link Connnection
FRAD
Network
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VoFR Protocols
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Audio
G.711
G.726
G.729
FAX
FRF.11
Control & Management
FR
Connection Management
FR LMI
Q.933 A
Q.922 Switching and Processing
Physical Layer (Serial Port)
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FRF-11 Requirements
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Service
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high speed links
Primary
Payload
Type
Signaled
Payload
Type
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Class 1
Class 2
low speed links (64Kbps)
Default
Voice
Algorithm
Mandatory:
-EADPCM – G.727
-Transmit rate 32 Kbps
-Receive rate 32 Kbps,
24 Kbps, 16 Kbps
Mandatory:
- CS ACELP-G.729/G.729
AnnexA
Other Voice
Optional:
-PCM-G.711;
-ADPCM-G.726
Optional:
-MP-MLQ G.723.1
-LD-CELP-G.728
Data
Optional
Optional
Fax
Optional
Optional
Dial Digits
Optional
Mandatory
CAS
Mandatory
Mandatory
AIS
Mandatory
Mandatory
Encoded FAX
Optional
Optional
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VoATM – why?
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ATM is used in access and core networks
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ATM supports QoS
and so is more fitted for voice than other PSNs
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convergence: infrastructure, management
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carriers can deploy ATM to cabinets
achieve pair-gain
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VoATM – how?
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FAX
PBX
Public
ATM
Network
Headquarters
E1
Bridge/
Router
ETH
Bridge/
Router
ETH
2xE1
FAX
E1
E3
E1
PBX
PBX
ETH
Bridge/
Router
ETH
E1
Management
PC
Station
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E1
E1
PBX
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VoATM Protocols
Audio
Signaling & Management
ATM Connection
Management
G.711
G.726
G.728
G.729
FAX
ATM UNI 3.1
SSCF Q.2130
Proprietary
Voice Protocol
SSCOP Q.2110
AAL1/AAL2
AAL5
ATM Layer
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VoATM Options
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AAL1 unstructured circuit emulation (CES)
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AAL1 structured circuit emulation (CES)
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AAL1 dynamic bandwidth allocation (DB-CES)
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AAL2 variable bit rate VoATM
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AAL5 proprietary variable bit rate VoATM
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IWF Functionality for ATM Trunking
Call Handling
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CAS Signaling
IWF-IWF
Signaling
ATM Signaling/NM
for Provisionning
IWF-IWF
CAS/DTMF Signaling
Nx64 Kbps
AAL1/2
Voiceband Processing
AAL2
CAS Supervisory
& DTMF Address
Signaling
- Echo Cancellation
- Idle Pattern Detection
- Silence Suppression
- Bad cell/frame interpolation
- Voice Compression
- Fax/modem detection
- Fax/modem relay
Mapping
Function
DSS2
AAL1/2
SAAL
ATM
PHY
ATM Interface
PHY
Synchronuous
Timing
T1/E1 PBX
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VoIP – why?
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IP coverage has become universal
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price not dependent on distance
may not be dependent on duration
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new features possible
– web call centers
– whiteboard
– video conferencing
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VoIP protocols
Once upon a time
Unix users conversed over LANs
first official VoIP was VocalTec
first standard was H.323 suite
IETF came up with SIP
sometimes MGCP or MEGACO enough
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H.323 vs SIP
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H.323
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terminal
GW
MCU
gatekeeper
SIP
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H.245 channel
audio, video, data
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user agent (UAC,UAS)
GW
conferencing
registrar, redirect server
proxy
SDP
extensions
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Some ITU-T VoIP Standards
H.320: Multimedia conferencing on ISDN
H.321: H.320 over ATM
H.322: H.320 over iso-ethernet LANs
H.323: Multimedia conferencing on Packet Nets
H.324: Multimedia conferencing on POTS
H.225 - Call Signaling, PDU, Packetization
H.245 - System Control
T.120 - Data and Conference Control
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H.323 Protocols
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Call Establishment And Control
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Presentation
Addressing
H.225
RAS
speech coder DTMF
DNS
RTP/RTCP
H.245
UDP
Addressing
H.225
Q.931
DNS
TCP
IP
Link
Physical
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H.323 Network
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H.323
Endpoint
H.323
H.323
Gatekeeper
Proxy
GATEWAY
H.320
(over ISDN)
Switched
Circuit Network
(POTs & ISDN)
Internet
H.323
Endpoint
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H.324
(over POTS)
Speech-Only
(telephones)
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VoIP – SIP
H.323 is a telephony-type protocol
SIP is a more standard IP protocol (similar to http)
INVITE sip:[email protected] SIP/2.0
From: VoP student
To: Yaakov (J) Stein
Call-ID: [email protected]
CSeq: 1 INVITE
Subject: How to use SIP
Content-Type: application/sdp
ACK sip: [email protected] SIP/2.0
etc.
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VoIP – SIP
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CONFERENCE MANAGEMENT
APPLICATIONS
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CONFERENCE SETUP AND
DISCOVERY
CONFERENCE
CONTROL
SDP
RSVP
SAP
UDP
SIP
HTTP
SMTP
MEDIA AGENTS
DISTRIBUTED
CONTROL
TCP
AUDIO
VIDEO
RTP
RTCP
SHARED APPS
RELIABLE
MULTICAST
UDP
IP and IP MULTICAST
Link
Physical
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MGCP and MEGACO
MGCP
 MG, MGC
 endpoint
 connection (2 endpoints)
 signals (MGC->MC)
 events (MG-> MGC)
 text grammar
 SDP
 packages
MEGACO
 MG, MGC
 termination
 context (N terminations)
 signals (MGC->MC)
 events (MG-> MGC)
 text or binary grammar
 SDP
 even more packages
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VoDSL – why?
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DSL uses existing under-utilized last-mile
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residential customers already universally connected
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can converge telephony and Internet
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voice is the killer-app, voice supplies revenues
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CLECs can compete with ILECs w/o rebuilding
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CLECs need to purchase far fewer Class-5 switches
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new features can be offered
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VoDSL – how?
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ATM
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V.5.2
PSTN
Voice
Gateway
Public ATM
Network
DSLAM
ATM
ATM
BAS
IP
ATM
xDSL
Internet
IAD
ATM
xDSL
IAD
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TDMoIP – why?
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VoIP has very high overhead, due to session level encapsulation
VoIP only handles a small number of the PSTN features
VoIP introduces a large amount of delay
VoIP degrades voice quality
VoIP is expensive and requires “forklift upgrade”
TDMoIP adds low overhead, since it transfers trunks
TDMoIP is transparent to PSTN signaling
TDMoIP introduces minimal delay
TDMoIP does not compress voice, so only degradation is delay
TDMoIP is inexpensive and evolutionary
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TDMoIP – how?
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TDMoIP uses UDP/IP
TDMoIP adds an additional pseudowire header
0
1
2
3
01234567890123456789 012345678901
FORMID
L RZ
length
sequence number
TDMoIP uses AAL1 or AAL2 adaptation
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VoCATV – why?
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CATV is existing under-utilized infrastructure
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in many areas
majority of residential customers already connected
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can converge TV, Internet and telephony
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cable full-duplex upgraded for pay-per-view
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can deliver 30 Mbps DS over 50 KM range
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competes with DSL access
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Cable modems
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CABLE
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MODEM
CMTS
CATV
HEADEND
fiber
OPTICAL
FIBER
CABLE
coax
COAXIAL
MODEM
AMPLIFIER
NODE
CABLE
MODEM
shared BW
CABLE
MODEM
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Cable modems - continued
In US:
DOCSIS - Data Over Cable System Interface Specification
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Specification for high-speed data-over-cable systems
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IP based
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DOCSIS 1.0 designed for transparent bi-directional traffic
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DOCSIS 1.1 enhancements:
– BW management / Prioritization features (QoS)
– Higher security
Cable modems do not monitor each other so Ethernet not possible
Adopted by ITU as J.112
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Multiple Standards
Incumbent standard for set-top boxes in Europe
DVB/DAVIC Digital Broadcast Video / Digital Audio Video Council
This standard is based on ATM
DVB2.0 “EuroModem” adopted by ETSI as ETS-300800
European Cable Consortium supports EuroDOCSIS
DOCSIS with DVB-compliant physical layer
IEEE developed 802.14
not gained support, but may be the next generation
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VoCATV
CableLabs added other protocols for VoCATV
 NCS Network Call Signaling
 MGCP
 IPSec authentication (DES)
 Optional fax-relay service
And additional features
 BTI Broadband Telephony Interfaces billing
 4 hour lifeline service
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