Transcript Internet-Future - Indian Institute of Science

Internet: Where is it Going?
Kumar N. Sivarajan
ECE Department
Indian Institute of Science
Bangalore 560 012, India
e-mail: [email protected]
Fax: 91-80-334-7791, Phone: 91-80-309-2658
Web: http://www.ece.iisc.ernet.in/~kumar/
February 26, 1999
Mr.KUMAR.:
Mr.KUMAR.:
Outline
• Packetized voice
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QoS
High-speed routers
Differentiation and pricing
Distance education
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
1
Internet: Salient Features
• Packet-switched (telephony is circuit-switched)
• Datagrams (each packet is independent)
• Best-effort (no guarantees)
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
2
Circuit- versus Packet-Switching
• Packet-switching is best-suited for short and/or bursty data
transfers
– Web browsing
– Remote terminal access
– Short emails and small file transfers
• Circuit-switching is best-suited for long-lived and/or
continuous data transfers
– Voice/telephony
– Video transmission
– Large file transfers
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
3
Circuit- versus Packet-Switching (contd.)
• But any network can support all (or most) traffic types (some
inefficiently)
– Data over a telephone network using a modem
– Telephony over the Internet
• Choice of circuit- or packet-switching depends on the dominant
traffic
– Traffic on the Internet is mostly data
– Traffic on the telephone network is mostly voice
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
4
Integrated Networks
• One network for all applications
• Telephone network as the universal network
– Works better if voice is the dominant traffic
• Internet as the universal network
– Works better if data constitute the dominant traffic
• Trend: Overall data traffic volumes have exceeded, or will
exceed, voice traffic volumes
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
5
Internet as the Universal Network
• Internet, as is, works fine for delay-insensitive traffic
– Few changes needed if e-mail is the main application
• Enhancements needed to support voice, and other delay-sensitive
traffic
• Voice over the Internet
– Voice is packetized
* Loosely analogous to ``modems'' for data transmission in
telephone networks
– Each packet is sent over the Internet like a data packet
– Voice packets are reassembled into a continuous stream at the
receiver
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
6
Internet as the Universal Network (contd.)
• To work well, voice packets must not be delayed much in the Internet
• Works if the network is lightly loaded
• Requires modifications to the Internet to work in moderate to heavily
loaded conditions
• Internet telephony is a reality but not widespread in the public Internet
• Potential Trend: Internet telephony may partially substitute corporate
PBX networks in companies with well-/over-engineered intranets
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
7
Classes of Service
• Differentiate traffic types within the Internet
– Voice (delay-sensitive) traffic is given priority over email
(delay-insensitive) traffic
* Reduces delay for voice (high priority) traffic
– Works well if voice (high priority) traffic is not the dominant
traffic
• Proposed for use in the Internet (DiffServ)
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
8
Internet Access
• Wireless access is gaining popularity
– Convenience
– On-road access to email through cell-phones
• Mobile access is becoming a necessity
– Globe-trotting executives
• Mobile IP: Mobility solution at the IP or network layer
• Mobility solutions at the TCP or transport layer
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
9
Quality of Service
• Applications may start to request quality of service (QoS)
guarantees
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– Delay should be  x milliseconds
Protocols needed to signal required QoS to routers along the path
and the destination
– ReSource reserVation Protocol (RSVP)
Routers need to implement appropriate scheduling to provide QoS
Requires successive packets in a stream/flow take the same path
Departure from traditional datagram view of routing
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
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Routing and Forwarding
• Next hop router for packet determined by destination IP address
• Two components:
– Route computation: fill up the routing table
– Packet forwarding: look up the routing table
• Innovations in forwarding enable high-speed routers
– New algorithms
– Identifying streams/flows and label-switching
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
12
Premium Services and Pricing
• With different services, flat pricing may disappear
– Users pay for what they want or get
• Requires development of extensive management and billing
software
– Along the lines of telephone networks
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
13
Multicast
• Only one copy of each packet traverses a link
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
14
Distance Education
• Distance education gaining rapid acceptance
• Internet is a more accessible, interactive and cost-effective medium
compared to television
• One copy of each packet for each receiver increases required
bandwidth
• Solution: IP multicast
• This lecture is being multicast on the Internet!
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
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Summary of Trends
• Packet telephony in corporate intranets
• Wireless and mobile access
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Fiber/WDM intercontinental backbones
QoS support in routers
Premium services
Distance education
• Internet as the universal network
Kumar N. Sivarajan
Introduction to Web based Education, Indian
Institute of Science
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