CSG mini-WorkshopVoice over IP

Jim Jokl – Virginia

Susan DeLellis – Harvard

May, 2001

VoIP Systems: Lots of definitions

PBX VoIP line or trunk card - A Call path between IP phones via PBX Initial releases by Lucent, NEC, others

PBX VoIP line or trunk cards - B Call path between IP phones via LAN Nortel, Siemens, others have systems Most PBX manufacturers working towards this type

of functionality

Major advantage: phone features

More VoIP System Definitions

LAN-based Systems Call setup via LAN call processing server Call path between all peripherals via LAN Cisco Call Manager Siemens HiPath Xpress Nortel Business Communications Manager Others

LAN-based systems generally limited ACD, console, call center applications

Packet Voice: What is different?

Traditional Phone Switch Voice over IP (VoIP)

Phone Switch

Phone

Phone

PhonePhone Phone

Phone

PSTN

Campus Network

Routers, hubs, switches

PSTN

Gateway

Call Manager

Network Capacity for Multimedia Applications

05

10152025303540

Percent

Method

Percent of Standard Ethernet

VoIPNetMeetingMPEG-4VCONWMMPEG2 (a)MPEG2 (b)

Network Capacity for Packet Voice Services

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

G.711 G.726 G.728 G.729 G.723.1 G.723.1

Voice Codec Type

% o

f E

the

rne

t R

eq

uir

ed

0

10

20

30

40

50

60

70

80

90

100

Su

bje

cti

ve

Vo

ice

Qu

ali

ty

(%) % Ethernet

% Quality

Network Infrastructure for Voice over IP Support

Low latency Low loss Predictable packet arrival High availability

Minimal capacity

Network Quality of Service (QoS)

Goal: provide better service for some

Build lots of network capacity Layer 3 QoS Layer 2 QoS

QoS: Useful for?

Have we seen the light?

Solving capacity problems? Protect voice traffic?

Need a way to remap QoS parameters where traffic enters the network

Personal Computer

IP Phone

IP Phones and QoS

IP phone generates 802.1p CoS = 5 and IP precedence = 5

Switch in phone can clear PC’s QoS header settings

Phone and PC can be in different VLANs

Switched Network

Wall Jack

IP Telephones and Power

Powering options Via Ethernet cable Via wall power transformer

Phone power consumption Tested Cisco and Nortel phones Between 4 and 6.5 watts/phone

Large wiring closet 250 phones, 75% efficiency

Closet power: 400 Watts Powering phones – no worse than 72 switch ports

My Other Wireless Phone

Wireless Data VoIP

Symbol NetVision Phone H.323 on 802.11 But no DSSS yet (summer)

Spectralink NetLink Phone System VoIP-based Both FHSS and DSSS available Proprietary adapter integration

Killer App: 802.11b/PCS dual mode phone?

Wireless & QoS

Challenge: protect voice traffic Wireless LANs low bandwidth Easy to overload

SpectraLink Voice Priority (SVP) Retransmission modification Priority queuing in base station

Symbol Similar capabilities

Standards?

Preparations at VirginiaThe Network

New backbone this summer Layer 3 switching IP Precedence

Wiring Closet 802.1p/Q New edge switches will reclassify traffic

Policy management, multicast Closet UPS and cooling work

Are these VoIP costs?

VoIP at Virginia

Initial application: toll bypass AS-5300 Gateway – T1 to PBX 2600/3600/3810 at remote location Analog interface to remote PBX

Added Cisco Call Manager Couple dozen phones Voice mail issues Number portability

VoIP at Virginia

Siemens HiPath 5500 One dozen phones PRI connection to Hicom PBX CorNet features

Nortel Business Communications Manager Planned for summer

Symbol?

Next Steps

Continue to prepare network for converged applications

Select a VoIP system for larger pilots Harvest some low hanging fruit

Safe areas Telecommuters Wireless?

Solve the wired/wireless VoIP question Continue to watch technology

Issues: Financial Model

Converged networks, especially VoIP, break most existing funding models

What to bill for Wall outlet? MAC Address? IP phone or soft phone? A tax based on headcount or NASF?

Central funding?