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Aloha Dr. Abramson: Could We Eat The Telco’s Lunch? Evolution of Computer Networking

Aloha Dr. Abramson: Could We Eat The Telco’s Lunch? Evolution of Computer Networking. Ravi Prakash Department of Computer Science. create your future. www.utdallas.edu. Surf the Net or Net the Surf?. 1970: network multiple University of Hawaii campuses. Wireless hub-and-spoke:

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Aloha Dr. Abramson: Could We Eat The Telco’s Lunch? Evolution of Computer Networking

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  1. Aloha Dr. Abramson: Could We Eat The Telco’s Lunch?Evolution of Computer Networking Ravi Prakash Department of Computer Science create your future www.utdallas.edu

  2. Surf the Net or Net the Surf? • 1970: network multiple University of Hawaii campuses. • Wireless hub-and-spoke: • Source to central campus. • Broadcast received signal to destination. • What if multiple sources transmit concurrently?

  3. ALOHA: Multiple Access

  4. From ALOHA to Ethernet • No central relay. • Listen before speaking. • Jamming signal on collision. • Random back-off and retry.

  5. The Past: Circuit Switched Request Reservation based. Dedicated resources. Guaranteed quality of service Resource utilization? Time Response Data Send entire message

  6. Do Computers Talk Like That? • No, no, no, no, ………………..no, no, no, …………………., no, no, no, no, ………………………………., no, no, ….. • Kleinrock et al.: Why waste resources? • Unlearn what Ma Bell taught us. • Learn from the Post Office instead • IP Datagrams

  7. Towards Packet Switching Time Time

  8. Statistical Multiplexing

  9. Routing & Packet Switching Source Destination

  10. Danger, Will Robinson! • Packets being dropped by routers! • Packets corrupted over links! • Network becoming too big to discover routes!

  11. The Reliability Question • The TCP answer • Cerf & Kahn, 1974 • If at first you don’t succeed, try, try, try again. • Acknowledgments. • Timers. • Retransmissions.

  12. Too Big To Fail?Chop, chop, chop AS1 AS3 X AS5 Y AS2 AS6 AS4

  13. Hierarchical Routing Stub AS AS1 Stub AS IDR IDR AS3 AS5 IDR Transit AS Transit AS AS2 Inter-AS path IDR AS6 IDR IDR: Intra-domain routing AS4 IDR Transit AS

  14. The Crash of October,1986 • NSFnet backbone traffic dropped from 32 kbits/s to 40 bits/s! • Blame it on TCP. • If at first you don’t succeed, try, try, try again…but don’t be bull-headed. • Van Jacobson (1987): congestion-control algorithm.

  15. Network Congestion

  16. TCP’s Congestion & Flow Control Congestion Avoidance Slow Start

  17. Design Principles • Distributed control. • Keep the network core simple. • Push all the complexity to the edge of the network. • Fundamentally different from the Telco approach. • Facilitates creation of new applications. • Has security implications.

  18. Killer (?) Applications • Email • FTP • Web browsing & search • Voice over IP • Torrent • Streaming audio and video

  19. Winners and Others Winners include: • Google • Yahoo • Amazon • Skype • Vonage • Netflix Non-winners: • Verizon • AT&T…at&t…at&t • Time Warner • Sprint • Comcast

  20. Net Neutrality Debate • Carriers/ISPs unable to share in the profits of content providers. • Are carriers trying to stifle competition? • Deep packet inspection • Metered data transport • Bundling • Telefonica intends to charge Google for its traffic.

  21. Oh What a Ride! • Last 20 years: • 9600-baud modem to 10 Mbps FIOS at home. • Plain text email to elaborate attachments. • Travel agents to Travelocity. • AT&T to Skype and Vonage. • $3/min to $19.95/month unlimited to India.

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