Cisco - Introduction to Voice over IP and other Integrated Services 402

402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

Introduction to Voice Over IP and Other Integrated Services Session 402 402 1029_05F9_c3

© 1999, Cisco Systems, Inc.

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Introduction

“ Voice Is “Just” Another Latency-Sensitive IP Application

” 402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

Agenda • Why Multiservice Networks? • What Is Multiservice? Voice Networking Overview Voice Over Data Network Transport Mechanisms Multiservice Network Architectures

• How Does Voice Over IP Transport Work? Applications Challenges and Solutions

• How Does an IP Phone System Work? • When Can I Implement IP Multiservice? 402 1029_05F9_c3

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Multiservice—Why Now? Data

Voice Data

Voice Data Exceeds Voice Over Voice Net

Bigger, Cheaper Bandwidth

QoS Advances

Open Standards

Cost Savings Network Consolidation Usage Charges Toll Charges

DSP

H.323/MGCP FRF.11/12 AAL1/2/5

IP Precedence, RSVP 802.1p, CiscoAssure 402 1029_05F9_c3

DSP

Digital Signal Processor Advances 5

© 1999, Cisco Systems, Inc.

New Integrated Applications (The Big Ones!) FAX

Unified Messaging

Ugh! Pager

Cell

Email

Voice Mail

Network Enabled Call Centers 402 1029_05F9_c3

© 1999, Cisco Systems, Inc.

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• • • • •

Click-to-Talk Web Click-to-Call Back Skills-Based Routing Assisted Web Navigation Computer Telephony Integration (CTI) • Work From Home 6

3

Agenda • Why Multiservice Networks? • What Is Multiservice? Voice Networking Overview Voice Over Data Network Transport Mechanisms Multiservice Network Architectures

• How Does Voice Over IP Transport Work? Applications Challenges and Solutions

• How Does an IP Phone System Work? • When Can I Implement IP Multiservice? 402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

Telephony and Data Architecture Fundamentals Comparison PBX

Switch Corporate Location

IXC Corporate Location Class Class 55

Router

LEC

Intranet

Class Class 55

Router

Class Class 55

PBX

Corporate Location

Corporate Voice Network with PBXs (Private Branch Exchange) 402 1029_05F9_c3

Internet

Router

Switch

Corporate Location

Corporate Data Network with Switches and Routers

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Voice and Data Switching Comparison Class 5 Switch

Multilayer Switch Router Switch

• Handset aggregator

• Computer aggregator

• All telephones get a single analog/digital line (DS0)

• All devices get dedicated bandwidth 10/100/1000 Mbps (autonegotiation)

• All devices have a phone number defined on the switch • All devices can simultaneously make a call (calls < trunk DS0s) • Path selection based on static least cost routing or ARS 402 1029_05F9_c3

• All devices have an IP address defined on the host • All devices run at full line rate (bandwidth < uplink) • Path selection based on dynamic routing protocol lowest cost 9

© 1999, Cisco Systems, Inc.

Voice Network Least Common Denominator Quantize 256 Steps Using 8 Bits

Sample 8,000/sec DS0 = Nyquist Frequency 64Kbps

4000 Hz Analog Signal Sample Compand Quantize Encode

Analog Audio Source

Frame = 0101

Everything is Bits

Pulse Code Modulation (PCM) DS0 402 1029_05F9_c3

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5

Digital Signaling Scheme T1/DS1 DS1—Extended Super Frame (8 X 24 Bytes = 192 Bit Frame) T1—Coding (Ones Density)—AMI, ZCS, B8ZS 1

2

3

4

5

6 A

7

8

9

10 11

1001100x

DS0

On-hook Off-hook

12 18 24 13 14 15 16 17 19 20 21 22 23 B C D

0110011x

No-ring

Ring

Robbed Bit or Channel Associated Signaling 402 1029_05F9_c3

1

2

3

4

5

6

7

8

9

*

0

#

Dual Tone Multi-Frequency 11

© 1999, Cisco Systems, Inc.

Today’s Carrier Voice Infrastructure Customer Premise

Interexchange

LocalCO Class 5 DS0 Switch

Class 4 Switch

DS1

Class 4 DS0 Switch

DS0

DS1

DS1

3/1 DACS

DS0 DS1

DS3

DS3

402 1029_05F9_c3

OC48

Class 5 DS0 Switch DS1

3/1 DACS DS3

DS3

SONET ADM

OC3/12

Customer Premise

Local CO

DS3

DS0 DS3

DS1

SONET ADM

OC48

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OC48

OC3/12

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Voice Transport Mechanisms Layer 3—VoIP

Layer 2—VoFR, VoATM

• Operates in heterogeneous network (ubiquitous)

• Requires rigid homogenous network or L2 gateways

• Connectionless (requires sequence numbers)

• Connection oriented (frames arrive in order)

• “Soft” QoS

• “Hard” QoS

• Layer 2 and 3 overhead

• Layer 2 overhead

• Standards-based H.323 (MGCP coming)

• Standards based (FRF.11/12, ATM AAL1/2/5)

402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

IP Ubiquity H.323 Endpoint A Voice

Token Ring

Token Token Ring Ring

IP UDP RTP Voice

Packet

IP UDP RTP Voice

Frame

IP UDP RTP Voice

R1 ATM or Frame Relay

FR FR or or ATM ATM

R2

IP UDP RTP Voice

IP UDP RTP Voice

Ethernet

802.3 802.3

e

IP UDP RTP Voice IP UDP RTP Voice

H.323 Endpoint B 402 1029_05F9_c3

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Voice 14

7

Enterprise Multiservice IP Core Backbone PSTN PBX

PBX Router

Router

QoS IP Network

Internet

Vancouver

New Orleans

Reduced Toll/Circuit Costs Infrastructure Consolidation Efficient Bandwidth Consumption 402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

Agenda • Why Multiservice Networks? • What Is Multiservice? Voice Networking Overview Voice Over Data Network Transport Mechanisms Multiservice Network Architectures

• How Does Voice Over IP Transport Work? Applications Challenges and Solutions

• How Does an IP Phone System Work? • When Can I Implement IP Multiservice? 402 1029_05F9_c3

© 1999, Cisco Systems, Inc.

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VoIP Uses ITU H.323 System Control and User Interface

Video I/O Equipment

Audio I/O Equipment

User Data Applications T.120

Video Codec H.261, H263

Audio Codec G.711, G.722, G.723, G.723.1, G.728, G.729

System Control H.245 Control Call Control H.225.0 RAS Control H.225.0

Session Layer and Above

Receive Path Delay

H.225.0 Layer LAN Stack 402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

ITU H.323 Components H.323 Terminal

H.323 Terminal

Gatekeeper

Gateway

Internet

Internet

PSTN

MCU

H.320 Terminal (ISDN) H.324 Terminal (POTS) Speech Only

H.323 Terminal 402 1029_05F9_c3

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H.323 VoIP Layers IP Layered Model

H.323 VoIP Model

User

Caller Email ID E.164 Phone No. Audio Codec (G.711, G.729, G.723.1,..)

Application Presentation Session TCP

402 1029_05F9_c3

H.225, H.245, RTP, RTCP UDP Port Number

UDP IP

IP Address

Data Link

Frame Relay DLCI, 802.3 MAC, ATM VPI/VCI

Physical

V.35, T1, T3 19

© 1999, Cisco Systems, Inc.

Voice CODEC Cheat Sheet Mean Native Encoding Voice Opinion Bit Rate Compression Score Quality Kbps

BW

Music Dual DTMF CPU on Comp Hold

G.711 PCM

4.1

64

A

D

A

A

A

A

G.726 ADPCM

3.85

32

B

C

B

B

B

B

G.728 LD-CELP

3.61

16

C

B

B

C

C

C

G.729 CS-ACELP

3.92

8

A

A

B

B

C

C

G.729a CS-ACELP

3.7

8

B

A

C

C

B

D

G.723.1 ACELP

3.65

5.3

C

A

C

D

C

D

402 1029_05F9_c3

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Code Excited Linear Prediction (CELP) Cake A/D

DSP

Code 16-Bit Linear PCM

Packet

Cake Recipe $0.32 10.1.1.1

Code Look-up

Ingredients: A-sound K-sound

Directions: Play K, A, and K

Recipe or Code Book 402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

H.323 End Point to End Point Signaling Assumes Endpoints (Clients) Know Each Others IP Addresses V

V

H.323 Gateway

H.323 Gateway Setup Connect

Signaling Plane

H.225 (TCP) (Q.931)

Capabilities Exchange Open Logical Channel

H.245 (TCP)

Open Logical Channel Acknowledge

Bearer Plane

402 1029_05F9_c3

RTP Stream RTP Stream RTCP Stream

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Media (UDP) Cisco Implementation Note: UDP ports 16384 through 16384 + (4 x the number of channels on the device)

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RTP/RTCP—RFCs 1889/1890 • End-to-end network transport function Payload type identification—voice, video, compression type Sequence numbering Time stamping Delivery monitoring

• RTCP (Real-Time Control Protocol) V

4 Bytes E

CC

R

M

Payload Type

Sequence Number

4 Bytes

RTP Timestamp

4 Bytes

Synchronization Source (SSRC) ID

402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

H.323 Gateway G.711 PCM G.726 ADPCM G.728 LD-CELP G.729 CS-ACELP G.729A CS-ACELP G.723.1 ACELP

QoS IP Network

G.711 PCM Analog

L2 IP UDPRTP Voice

Frame Relay ATM Ethernet FDDI Token Ring 402 1029_05F9_c3

PSTN

Gateway

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FXO FXS E&M T1 PRI 24

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Router Voice Interfaces Switch

FXO

Switch

FXS

T1/PRI

T1/PRI

Switch

E&M

E&M

• • • • 402 1029_05F9_c3

FXO

FXS

FXO—Foreign Exchange Office FXS—Foreign Exchange Station E&M—Ear and Mouth PRI—Primary Rate Interface 25

© 1999, Cisco Systems, Inc.

Dial-Peer Configuration (Static Routing) FXS

R1

X1234

QoS s0 IP/FR/ATM R2 WAN 10.1.1.1 10.1.1.2

r1# dial-peer voice 1234 pots destination-pattern 1234 port 1/0/0 ! dial-peer voice 4000 voip destination-pattern 4... session target ipv4:10.1.1.2

s0

Local

VoIP

FXS

r2# dial-peer voice 4321 pots destination-pattern 4321 port 1/0/0 ! dial-peer voice 1000 voip destination-pattern 1... session target ipv4:10.1.1.1

X4321

Local Port IP Address

dial-peer voice 4000 vofr destination-pattern 4... session target serial0 122

VoFR

dial-peer voice 1000 vofr destination-pattern 1... session target serial0 221

Interface DLCI

dial-peer voice 4000 voatm destination-pattern 4... session target serial0 1

VoATM

dial-peer voice 1000 voatm destination-pattern 1... session target serial0 1

ATM VCD

402 1029_05F9_c3

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Basic Trunk/Route Replacement PBX PRI

PSTN

PBX

PRI

Telco Switch

E&M

T1/PRI Cisco 3600/2600

Branch Office

AS5300

PRI

402 1029_05F9_c3

Central Site

(Intranet/Internet)

AS5300

Call Comes In

AS5300

QoS WAN

PRI

AS5300

PRI

PSTN

PSTN

PSTN

New Orleans

Vancouver

San Jose

Bypass PSTN

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© 1999, Cisco Systems, Inc.

Router-Based Key System 556-1001

Key System 556-1002 556-1003

555-1001

10.1.1.1 555-1002

PBX

E&M R1 R1

555-1003

T1/PRI 555-1999

PSTN

402 1029_05F9_c3

QoS IP WAN

556-1004 R2 R2

r2# FXO dial-peer voice 5561001 pots destination-pattern 5561001 port 1/0/0 ! PSTN dial-peer voice 5551000 voip destination-pattern 5551... session target ipv4:10.1.1.1 ! dial-peer voice 91 pots destination-pattern 9 port 3/0/0

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FXS 556-1005 556-1006 556-1007 556-1008

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Off Premise Extension (OPX) X1001 X1002

Voice Mail

PBX

X1003

OPX FXO

QoS IP/FR/ATM WAN

R1

10.1.1.1

X1004

402 1029_05F9_c3

X1006 R2

FXS

X1007

10.1.1.2

T1/PRI

PSTN

X1005

X1008 r1# dial-peer voice 1100 pots destination-pattern 1100 port 1/0/0 ! dial-peer voice 2000 voip destination-pattern 2... session target ipv4:10.1.1.2 ! voice-port 1/0/0 connection trunk 2100

r2# dial-peer voice 2100 pots destination-pattern 2100 port 1/0/0 ! dial-peer voice 1000 voip destination-pattern 1... session target ipv4:10.1.1.1 ! voice-port 1/0/0 connection trunk 1100 29

© 1999, Cisco Systems, Inc.

VoIP Full Mesh Dial-Peers 192.168.1.1 X1001

FXS

192.168.2.1

R1 R1

R2 R2 2…

Common dial-peers dial-peer voice 1000 voip destination-pattern 1… session target ipv4:192.168.1.1 ! dial-peer voice 2000 voip destination-pattern 2… session target ipv4:192.168.2.1 ! dial-peer voice 3000 voip destination-pattern 3… session target ipv4:192.168.3.1 402 1029_05F9_c3

3…

X2001

1… 3…

QoS IP WAN 1…

2…

192.168.3.1 FXS

FXS

FXS

R3 R3

X3001

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X3002

Destination Pattern

Site specific dial-peers dial-peer voice 3001 pots destination-pattern 3001 port 1/0/0 ! dial-peer voice 3001 pots destination-pattern 3002 port 1/0/1 30

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H.323 Gatekeeper Call Control/Signaling Gatekeeper Registration Gatekeeper

H.323 Gateway Learns of Gatekeeper via Static Configuration RRQ

RCF RCF

Hello: I am registering my Name or E.164 address (Gateway A) Gateway A

RRQ

IP QoS WAN

Hello: I am registering my Name or E.164 address (Gateway B) Gateway B

RAS—Registration Admission and Status UDP Transport Port 1719 RRQ—Registration Request RRJ—Registration Reject RCF—Registration Confirm 402 1029_05F9_c3

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© 1999, Cisco Systems, Inc.

H.323 Gatekeeper Dial-Peer Scaleability Gatekeeper A (Zone A)

1. ARQ (Admission Request): I have a call for Gateway B

IP QoS WAN

ARQ ACF

3 H.323 Call Setup Gateway B

Gateway A

2. ACF (Admission Confirm): Yes you can, here’s its IP Address X.X.X.X 402 1029_05F9_c3

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VoIP Low Speed Link (<768 Kbps) Challenges and Solutions Challenge

Cisco Solutions Intelligent Queuing

Congestion Delay and Delay Jitter

WFQ, IP Precedence, RSVP, Priority Queuing

Packet Residency

Interleaving

Slow Link Freeze-out by Large Packets

FRF.12, MLPPP, IP MTU Size Reduction, Faster Link

Bandwidth Consumption

Compression

Header Size on Low Bandwidth Links

Codecs, RTP Header Compression, Voice Activity Detection

Traffic Management

WAN Oversubscription, Bursting 402 1029_05F9_c3

Router Traffic Shaping to CIR, High Priority PVC, Data Discard Eligibility 33

© 1999, Cisco Systems, Inc.

Congestion Avoidance Solutions Intelligent Queuing Configurable Queues Two 60-Byte Voice Packets 24 kbps Rate

Voice Traffic Preferred 1

1

2 1

2

1

2

De-queue

1

1

56 kbps Line Rate

Classify

1500-Byte “Ping” Flow at 1 Mbps

Interface Buffer Resources

Transmit Scheduling

Weighted Fair Queuing (WFQ) Resource Reservation Protocol (RSVP) Priority Queuing 402 1029_05F9_c3

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Packet Residency Solutions FXS

56K WAN

s0

R1

s0

10.1.1.1

X1234

R2

FXS

10.1.1.2

X4321

Receive Playout Buffer Gap of 214 ms 1500 Byte Data Packet

0 20 40 60 80 100

200

240

300

400

300

400

Interleaving with FRF.12 or MLPPP Data

0 20 40 60 80 100 402 1029_05F9_c3

200

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© 1999, Cisco Systems, Inc.

VoIP Bandwidth Solution

Version

IHL

Type of Service

Identification Time to Live

Total Length Flags

Protocol

Fragment Offset Header Checksum

Source Address Destination Address Options

V=2

P

Padding

Source Port

Destination Port

Length

Checksum

X

CC M

PT

RTP Header Compression

Sequence Number

Timestamp Synchronization Source (SSRC) Identifier

• 20 ms @ 8 kbps yields 20-byte payload • IP header 20; UDP header 8; RTP header 12 2X payload! • Header compression 40 bytes to 2 or 4 bytes • Hop-by-Hop on slow links <512 kbps • CRTP—Compressed Real-time Protocol

402 1029_05F9_c3

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Agenda • Why Multiservice Networks? • What Is Multiservice? Voice Networking Overview Voice Over Data Network Transport Mechanisms Multiservice Network Architectures

• How Does Voice Over IP Transport Work? Applications Challenges and Solutions

• How Does an IP Phone System Work? • When Can I Implement IP Multiservice? 402 1029_05F9_c3

37

© 1999, Cisco Systems, Inc.

IP Phone System Easy Adds/Moves/Changes IP Phone System 556-1001

555-1001 555-1002

PBX

E&M

556-1002

QoS IP WAN T1/FXO

555-1003

556-1003

T1/PRI 556-1004

555-1004

Call Manager

PSTN PSTN

CTI

Single Cable Plant 402 1029_05F9_c3

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Phone Initialization 1. Phones make DHCP request to get an IP address, gateway, boot server, etc. 2. Phones make TFTP boot file request to get CM IP addresses and ports 3. Phones register with CM and get templates 4. Phones display CM time and date and are ready to receive/place calls

Services: • DHCP • TFTP Server • Call Manager

402 1029_05F9_c3

3

2

1

QoS 3 IP LAN/WAN

2

1

39

© 1999, Cisco Systems, Inc.

Phone Call Control 1. Calling phone sends off-hook message to CM 2. CM directs phone to play dial-tone 3. Phone sends dialed digits to CM as they are collected 4. CM rings called party phone and accepts off-hook message 5. Calling phone initiates bearer VoIP RTP session with called phone 6. Call Manager is notified of disconnect and records call details

1

X1001 402 1029_05F9_c3

2

3

5

QoS IP LAN/WAN

5

4

RTP Bearer Plane (5 K or 64 Kbps)

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X1002 40

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Agenda • Why Multiservice Networks? • What Is Multiservice? Voice Networking Overview Voice Over Data Network Transport Mechanisms Multiservice Network Architectures

• How Does Voice Over IP Transport Work? Applications Challenges and Solutions

• How Does an IP Phone System Work? • When Can I Implement IP Multiservice? 402 1029_05F9_c3

© 1999, Cisco Systems, Inc.

41

Planning and Implementation • Today Tie-line replacement Toll-bypass Off Premise Extension (OPX) Router key system replacement Small office IP phone system (< 100 users)

• Tomorrow Virtual call centers Campus IP phone system (> 1000 users) Enhanced integrated data/voice applications Unified messaging 402 1029_05F9_c3

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Please Complete Your Evaluation Form Session 402

402 1029_05F9_c3

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402 1029_05F9_c3

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