1Michael Knappe - 02/25/99 © 1999, Cisco Systems, Inc. Voice over IP Industry Perspective: Net@EDU Michael Knappe EVBU Advanced Products Michael Knappe

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


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


A Climate for ChangeA Climate for ChangeA Climate for ChangeA Climate for Change

Global Deregulation

Voice

Bandwidth Explosion

Data

Open Standards

Technology

Performance

Cost


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


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


IP

New World ApplicationsNew World Applications

Branch Office

V

Headquarters (or SP)

Application Servers


Primary VoIP PlaysPrimary VoIP Plays

• Long distance solutions

T1/E1 aggregation

• Local exchange solutions

VoIP over cable / DSL

• Enterprise solutions

Integrated voice / data applications


VoIP TechnologyVoIP Technology


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


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


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


DSP DrivenDSP Driven

• Voice Compression

G.729, G.723.1

• Echo Cancellation

• Silence Suppression

• Fax / Modem Carriage

• Tone Detection / Generation

DTMF, Call progress


Quality of ServiceQuality of Service


End-to-end Voice QualityEnd-to-end Voice Quality

Clarity

Latency

Echo


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


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”


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


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


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


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


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


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


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


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


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


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


FuturesFutures


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


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


MultimediaMultimedia

• Better than PSTN quality audio

• Video

• Conferencing / data sharing apps


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


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


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.

Documents

1Michael Knappe - 02/25/99 © 1999, Cisco Systems, Inc. Voice over IP Industry Perspective: Net@EDU Michael Knappe EVBU Advanced Products Michael Knappe