1 © 1999, The Ohio State University 9 Dec 99 VoIP Technology Briefing Harpal Chohan Russell...

1© 1999, The Ohio State University 9 Dec 99

VoIP Technology Briefing

Harpal ChohanRussell Morrison

Enterprise Networking - The Ohio State University

The Ohio State UniversityThe Ohio State University

2

AgendaAgenda

• Voice as an application

• Overview of the PSTN

• VoIP toll by-pass

• IP Telephony

• Integrated Voice Architecture


3

Voice – What is it?Voice – What is it?Voice – What is it?Voice – What is it?

• Real-time, interactive

• Delay Intolerant – delay < 150 ms

• Jitter, packet loss

An application – Not a network

Characteristic Issues:-Characteristic Issues:-


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Constituent PiecesConstituent Pieces

• Media

• Signaling

• Services


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AgendaAgenda




• IP Telephony



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MediaMedia

• G.711 64 k (DS0)

• G.726 16, 24, 32, 40 k

• G.729 8 k

• G.728 16 k

• G.723.1 6.3/5.3 k Variable

- Analog- Analog

- Digital- DigitalPSTN

CO/CO/

PBXPBX


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SignalingSignaling

• Analog

• ISDN Q.930/Q.931

• SS7

PBXPBX

MediaTransport

Signaling

PSTN – SS7

COSwitch

COSwitch

ISDNPRI

HomeHomeOfficeOffice


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SS7 ElementsSS7 Elements

VoiceSig. &

VoiceVoice

SS7 SignalingSS7 Signaling

SSP SSPSSP

STP STPSTP

STPSTP STPSTP

Switch

SwitchSwitch

PBX

SCPSCPSCP


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SS7 Protocol StackSS7 Protocol Stack

SS7 LevelOSI Layer

Level 1Level 1

Level 2Level 2

Level 3Level 3

Level 4Level 4

Layer 1Layer 1

Layer 2Layer 2

Layer 3Layer 3

Layer 4Layer 4

Layer 5-7Layer 5-7

MTPMTP

TUPISUP

SCCP

TCAP


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AgendaAgenda




• IP Telephony



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Where does IP come in?Where does IP come in?

PBXPBX

PSTN

IP NetworkRouter

V

Router

V

H.323H.323

Toll BypassToll Bypass


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Multi-site VoIPMulti-site VoIP

PBX

IP WAN

PBX APSTN

H.323H.323

PBX B

PBX C

ISDNISDN

ISDNISDN

SS7SS7

GatekeeperGatekeeper


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Motivators for Enterprise VoIPMotivators for Enterprise VoIP

• Toll bypass – of course.

• Single wide area infrastructure – gotta have data connectivity anyway. Right?

• Consolidation of long distance volume.

• Custom dial plan (5 digit across all locations).

• Network Consolidation.


14

AgendaAgenda




• IP Telephony



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RemoteCampus

IP TelephonyIP Telephony

EnterpriseIP Network

IP PhonesIP Phones

IP PBXIP PBX

GatewayPBX/PBX/

Switch

PSTN


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Motivators for IP TelephonyMotivators for IP Telephony

• Single campus network infrastructure

• Portability – easy adds/changes

• IS Staff supporting voice and data??

• Unified Messaging

• Integrated services and features


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Voice MailVoice Mail

IP Telephony MigrationIP Telephony Migration


IP PhonesIP Phones

IP PBXIP PBX

Gateway

PBXPBX

PSTN

VoiceMailVoiceMail

Enterprise

Phone Network

Enterprise

Phone Network

PSTN


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PSTN

IP-Tel/VoIP at Ohio StateIP-Tel/VoIP at Ohio State

OSU CampusNetwork

IP PhonesIP Phones

IP PBXsIP PBXs

Gateway

PBXPBXPSTN

OSU Phone Network

Voice Mail

IP T1sIP T1s

RemoteSites


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Usual Deployment IssuesUsual Deployment Issues

• State of In-building networks

• Firewalls

• 911

• Power

• Change management – record keeping

• Dial Plans


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Dial PlansDial Plans

• Toll bypass VoIP – Phones already have E.164 identities

• IP Phones – Have IP addresses, and?


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Internet2

Talking Outside Your RealmTalking Outside Your Realm


IP PBXIP PBX

PSTN


IP PBXIP PBX


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Talking Outside Your RealmTalking Outside Your Realm


IP PBXIP PBX

PSTN


IP PBXIP PBX

Internet2


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AgendaAgenda




• IP Telephony



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VoiP Constituent PiecesVoiP Constituent Pieces

• Media, Transport & Gateways

• Gateway Control and signalling

• Services


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Integrated Voice ArchitectureIntegrated Voice Architecture

TDM, ATM, etc.TDM, ATM, etc.

SS7, ISDN, Q93xSS7, ISDN, Q93x

RTP/UDP/IP Gateways

H.323, SGCP, IPDC, MGCP, SIP

Open Services LayerOpen Services Layer

TransportTransport

ControlControl

ServicesServices

1 © 1999, The Ohio State University 9 Dec 99 VoIP Technology Briefing Harpal Chohan Russell...

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