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1Michael Knappe - 02/25/99 © 1999, Cisco Systems, Inc.
Voice over IP Industry Perspective: Net@EDUVoice over IP Industry Perspective: Net@EDU
Michael Knappe
EVBU Advanced Products
Michael Knappe
EVBU Advanced Products
2Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
AgendaAgenda
• IntroductionIntroduction
• VoIP Technology
• Quality of Service
• Futures
3Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Pulver.com Predictions for 1999
Pulver.com Predictions for 1999
• "Applications"
• VON Directory Services
• Development of "the" Lightweight, Protocol Agnostic Client
• IP based PBXs, NextGen Callcenters and other Enterprise IP Appliances
• Last Mile VON Technologies ( GSM/IP, Wireless IP, other)
• Support of H.323 / xGCP / SIP with Firewalls
• Broadband VON Implementations
• IP Telephony Multiple-Domain Billing Solutions
• NextGen IP based Switches
• Understanding SS7 / IN Convergence Issues
• VON Management Tools
• Multimedia Telephony
4Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
A Climate for ChangeA Climate for ChangeA Climate for ChangeA Climate for Change
Global Deregulation
Voice
Bandwidth Explosion
Data
Open Standards
Technology
Performance
Cost
5Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
U.S. LONG-DISTANCE TRAFFICU.S. LONG-DISTANCE TRAFFICin billions of gigabits per yearin billions of gigabits per year
1412
10
8
6
4
21997199719941994 20052005ProjectedProjected
Crossroads of ChangeCrossroads of Change
Data TrafficData Traffic
Voice TrafficVoice Traffic
6Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Communications Technology Shift
Communications Technology Shift
Internet1990-21st Century
Mainframe
1960-1970sMini1970-1980s PC/LAN1980-1990s
DataNetworking
VoiceNetworking
Analog PBXs
1960-1970s
Digital PBXs
1970-1990s
PC PBXs
1990-2000s
7Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
IP
New World ApplicationsNew World Applications
Branch Office
V
Headquarters (or SP)
Application Servers
8Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Primary VoIP PlaysPrimary VoIP Plays
• Long distance solutions
T1/E1 aggregation
• Local exchange solutions
VoIP over cable / DSL
• Enterprise solutions
Integrated voice / data applications
9Michael Knappe - 02/25/99 © 1999, Cisco Systems, Inc.
VoIP TechnologyVoIP Technology
10Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Generalized Gateway Architecture
Generalized Gateway Architecture
DSPEndpoint
CallTreatment
TelephonyStack
IPStack
BillingRSVP
Security &Authentication
Management & Provisioning
Station
Directory &Rendez-Vous
Services
Call DetailRecords
Digital/AnalogCAS, CCS
11Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Gateway Architecture (cont.)Gateway Architecture (cont.)
IOS Kernel
Session ApplicationDial PlanMapper
Voice API/SPI
Voice SessionProtocol (e.g.
H.323)
Telephony/CODEC Drivers
RTP/RTCP
RTP/UDP/IPCompression PPP Multilink Fragmentation/
Interleaving
Telephony Interfaces
RSVP
DSP Complex
TDM
•Session Application - Call treatment
•Dial Plan Mapper - model PBX dial plans
•Voice API - media-independent
•Session Protocol - H.323
•Telephony/Codec Drivers & Hardware - Platform Dependent
•IOS Support - Link Treatment & RSVP
12Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Protocol AgnosticismProtocol Agnosticism
• Distributed call control
Intelligent endpoint / dumb core
e.g H.323 / H.450
• Centralized call control
Dumb(er) endpoint / intelligent core
e.g SGCP / MGCP
• Hybrids
H.323 ‘trunks’ into SGCP servers
13Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
DSP DrivenDSP Driven
• Voice Compression
G.729, G.723.1
• Echo Cancellation
• Silence Suppression
• Fax / Modem Carriage
• Tone Detection / Generation
DTMF, Call progress
14Michael Knappe - 02/25/99 © 1999, Cisco Systems, Inc.
Quality of ServiceQuality of Service
15Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
End-to-end Voice QualityEnd-to-end Voice Quality
Clarity
Latency
Echo
16Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Latency
Usability of Voice Circuit as a Function of End-to-End Delay
Time (msec)
Uti
lity
0.0
0.5
1.0
0
100
200
300
400
500
600
700
800
TollQuality
I-Phone Technology is
Here Today
Improving I-Phone means:
• Lower PC Delay
• Lower Network Latency
• Tighten Network Jitter
SatelliteZone
CBZone
Fax Relay, Broadcast
Private NetworkVoFR & VoIPTechnology
17Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Delay Budget
Device Sample Capture
Encode Delay (Algorithmic Delay + Processing Delay)
Packetization/Framing
Move to Output Queue/Queue Delay
Access (up) Link Transmission
Backbone Network Transmission
Access (down) Link Transmission
Input Queue to Application
Jitter Buffer
Decode Processing Delay
Device Playout Delay
“The Network”
18Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Some Techniques to Improve “Network QoS”
WFQ - Weighed Fair Queuing
RSVP - ReSerVation Protocol
IP Precedence
CRTP - Compressed Realtime Protocol
MCML - Multi-Class Multi-Link PPP
19Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Bitwise Round Robin Fair Queuing
Simulates a TDM
Fair queue sorted to emulate TDM
Messages arrive in emission order
Queue order by simulated last bit delivery
Add weights to each queue to get WFQ
Rudeness No Longer Tolerated
20Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
RSVP
Applies to Unicast & Multicast Applications
Simplex & Receiver-Oriented
Transparent Operation Through Routers That Do Not Support It.
RSVP QoS Services
– Guaranteed Service - Mathematically Provable Bounds on End-to-End Datagram Queuing Delay/Bandwidth
– Controlled Load Service - Approximate QoS From an Unloaded Network for Delay/Bandwidth
RSVP Provides the Policy to WFQ
21Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
GW
PSTNGW
PSTNCallAgent
Admission OK or not OK
Aggregate Reservation
Scaleable RSVPScaleable RSVP
•GW Signals to Aggregation Point with RSVP•Aggregate Reservation Maintained with Modified RSVP•Aggregate Reservation Size Varies with Load•Admissions Policy Independent of Application Type•Aggregation Point is One Home for PEP
22Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
IP Precedence
Set IP Precedence higher on voice packets– This puts them in a different WFQ queue, resulting in isolation from best effort traffic
– Can be done by endpoint, proxy, or in routers through heuristics
Scales better than RSVP - can provide bulk QoS by customer or network
No admission control– Too much high-precedence traffic can still swamp the network
23Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
RTP Compression
20ms @ 8kbit/s yields 20 byte payload
IP header 20; UDP header 8; RTP header 12
– Twice size of payload!
Header compression: 40 bytes to 2-4 most of the time
Hop-by-hop: use only on the slow links
24Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Voiceband Quality Factors
Subjective Codec Quality–High MOS Coders
Delay & Delay Variation–Adaptive Jitter Buffer
Echo Cancellation–Voice Clipping–Doubletalk–Multiparty calls
Background Noise–Music On Hold–Ambient Noise
Error RecoveryBit Errors/Frame Loss
DTMF CarriageFAX, Modem CarriageSilence Suppression
Comfort Noise
Language Sensitivity
25Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Mean Opinion Score
Source Impairment
Codec ‘X’
Channel Simulation
“Nowadays, a chicken leg isa rare dish”
1 2 3 4 5
1 2 3 4 5
Rating Speech Quality Level of Distortion
5 Excellent Imperceptible
4 Good Just perceptible but not annoying
3 Fair Perceptible and slightly annoying
2 Poor Annoying but not objectionable
1 Unsatisfactory Very annoying and objectionable
MOS of 4.0 = Toll Quality
26Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Clear Channel MOS’s
MeanOpinionScore
5
G.711(64 kbit/sPCM)
4.1
G.726(32 kbit/sADPCM)
G.723.1(6.4 kbit/sMP- MLQ)
G.729(8 kbit/sCS-ACELP)
IS-54(8 kbit/sNA DigCellular)
3.8 3.9 3.93.44
3
2
1
27Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
MOS Under Varying Conditions
• Example: G.729– Avg Speech Level (-20 dBmO): 3.85– Low Input Level (-30 dBmO): 3.54– 2 Tandem codings: 3.46– 3 Tandem codings: 2.68– 5% BER: 3.24– 5% FER: 3.02
28Michael Knappe - 02/25/99 © 1999, Cisco Systems, Inc.
FuturesFutures
29Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Voice-enabled EverywhereVoice-enabled Everywhere
ATM Core
Circuit Core
Packet Core
ISP (a, b, c)
Corporate Gateway (a, b, c)
Content Network
Backbone/ Core
Aggregation
Router
Access
Dedicated/Frame Relay/ATM
Cable
DSL
SvcPolicyMngmt
ISDN/Dial
30Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Feature TransparencyFeature Transparency
• Goal: have all access points enabled for a common set of rich features
Caller ID, Transfer, Forward, Directory...
Consistent user interface
Feature phones, Q.SIG connectivity, black phone *codes
31Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
MultimediaMultimedia
• Better than PSTN quality audio
• Video
• Conferencing / data sharing apps
32Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Seamless GrowthSeamless GrowthSeamless GrowthSeamless Growth
1) Start with one Network2) Add Phones and Applications as needs evolve
Small / RemoteOffices Flexible
deployment
Easy expansion
Multiple Offices
33Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Mainframes & SNA
• Proprietary
• Closed
• Inflexible
• Monolithic
• Extremely expensive
• Old world speed
Open Standards Based Open Standards Based FlexibilityFlexibility
Open Standards Based Open Standards Based FlexibilityFlexibility
Traditional TelephonyTraditional TelephonyTraditional TelephonyTraditional Telephony Client/Server & TCP/IP
• Public standards
• Open systems
• Flexible
• Multivendor Support
• Inexpensive
• Internet Time
Packet TelephonyPacket TelephonyPacket TelephonyPacket Telephony
34Michael Knappe - 02/25/99 Cisco Systems Proprietary Information- Do Not Distribute- Confidential
Open ArchitectureOpen Architecture
• Cisco Networks Program Reference designs2-channel POTs interface VoIP endpoint
VxWorks OS, Hitachi SH3-DSP HW base
H.323 & SGCP stacks
• 3rd party call control - application developmentTAPI, JTAPI et al (Enterprise IP PBX)
Billing and IVR interfaces (Service Provider gateways)
350330_10F9_c1 © 1998, Cisco Systems, Inc.