a quick introduction to voice over internet protocol...purc 2004 internet basics • the basic...
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PURC 2004
A Quick Introduction to Voice A Quick Introduction to Voice over Internet Protocol (VoIP)over Internet Protocol (VoIP)
PURC Annual Conference 2004PURC Annual Conference 2004
Chuck JacksonChuck Jackson
PURC 2004
RoadmapRoadmap
•• Basics of packet communications as Basics of packet communications as used in the Internetused in the Internet
•• How voice is transmitted over packet How voice is transmitted over packet networks such as the Internet.networks such as the Internet.
•• Examples of VoIP uses and systems Examples of VoIP uses and systems •• Concluding thoughtsConcluding thoughts
PURC 2004
Internet Basics
• The basic building block of networks is the IP datagram.
• Analogy to datagrams—a postcard with – Destination address– Return address– A small amount of text
• A postcard might inform you of a friend’s holiday travels or remind you of a dentist’s appointment.
• The postal service doesn’t care which application (friend or dentist) sent the postcard—it just carries processed wood pulp with black marks.
PURC 2004
Protocol LayeringProtocol Layering
Physical Transport (e.g, Cable Modem)
IP (Internet Protocol)
TCP UDP
Applications (e.g., email, web pages)
Email Data (1000 bytes)TCP Header (20 bytes)
IP Header (20 bytes)
A Typical IP Datagram
PURC 2004
The Hourglass FigureThe Hourglass Figure
Source: Steve Deering, IETF 51
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VoiceVoice——Another Application over IPAnother Application over IP
• Voice requires about 10,000 to 100,000 bits per second.
• Can send those bits over IP—just as we send web pages or email.
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Alternative VoIP ArchitecturesAlternative VoIP Architectures
• PC to PC
InternetInternet
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Alternative VoIP ArchitecturesAlternative VoIP Architectures
• Phone to Phone via the Internet
InternetInternet
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Alternative VoIP ArchitecturesAlternative VoIP Architectures
• Phone to Internet to Gateway to PSTN
InternetInternetGATEWAY
PSTNPSTN
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Alternative VoIP ArchitecturesAlternative VoIP Architectures
• PSTN to Gateway to Internet to Gateway to PSTN
InternetInternet
GATEWAYGATEWAY
PSTNPSTN PSTNPSTN
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VoIP ExamplesVoIP Examples
• Xbox Voice• Windows messenger• AOL Instant Messenger• Motorola Phone Adapter (Vonage)• Cisco Phone• Cox Cable in Hampton Roads, Virginia
PURC 2004
Xbox LiveXbox Live
http://www.xbox.com/en-US/live/about/StarterKit-Retailers.htm
PURC 2004
MicrosoftMicrosoft’’s Explanation of the Benefits of Voice with Xboxs Explanation of the Benefits of Voice with Xbox
http://www.xbox.com/en-US/live/about/Article-Top10GetLive.ht
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Microsoft Windows MessengerMicrosoft Windows Messenger
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AOL Instant MessengerAOL Instant Messenger
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The Motorola Box Used by The Motorola Box Used by VonageVonage
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VonageVonage Uses this Uses this ArchtectureArchtecture
• Phone to Internet to Gateway to PSTN
InternetInternetGATEWAY
PSTNPSTN
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Motorola Box in Motorola Box in VonageVonage ArchitectureArchitecture
InternetInternetGATEWAY
PSTNPSTN
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Cisco 7970 IP PhoneCisco 7970 IP Phone
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Cox Cable in Hampton Roads, VirginiaCox Cable in Hampton Roads, Virginia
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Concluding ThoughtsConcluding Thoughts
• VoIP is one of many higher-level communications capabilites among devices connected to the Internet.
• VoIP is not an application.• VoIP is a capability that is part of many
applications. • VoIP capabilities are already pervasive.
– Microsoft Windows Messenger (part of XP)– AOL Instant Messenger– Xbox and Sony Playstation