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Globus Project Future Directions

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Globus Project Future Directions The Internet: Packet Switching and Other Big Ideas Ian Foster 2 The Internet 1969 2004 4 nodes 100s of millions 3 The Internet z Clearly a huge success in terms of not only impact but also scalability Some (not all) of the basic notions have scaled over eight orders of magnitude z What were underlying big ideas? Let’s say: Packet switching End-to-end principle Internet community & “standards” process z Also other important algorithms, e.g. Routing, naming, multicast z Common thread: (fairly) robust emergent behaviors from simple local strategies 4 Overview z Birth of the Internet Packet switching Process and governance z End-to-end principle E.g., congestion avoidance and control z Decentralized, adaptive algorithms Routing Naming Multicast 5 Simple Switching Network 6 Problem Statement z Many “stations” connected by point-to-point “connections” (with some redundancy) z Enable any station to send “messages” to any other station, despite diverse failure modes z And further Be efficient in use of network resources Support stations of diverse capabilities Support diverse applications & behaviors, including many not yet known (!) 7 “Traditional” Approach: Circuit Switching z A dedicated communication path between the two stations z Communication involves: Circuit Establishment z Point to Point from terminal node to network z Internal Switching and multiplexing among switching nodes. Data Transfer Circuit Disconnect z E.g., the telephone network 8 Circuit Switching z Once connection is established: Network is transparent Nodes seems to be directly connected Fixed data rate with “no delay” z However Can be inefficient: resources are dedicated to connection even if no data is sent Delay prior to usage of connection Public Switching Telecommunication Network 9 The generic component of the public switching telecommunication network is divided into: z Subscribers z Local loop (connects subscribers to the network) z Exchange (switching centers) (end office) z Trunks (connection between exchanges) (carry multiple voice channels using FDM or STDM) 10 History of the Internet: Application Pull z Emergence of (timeshared) computers supporting interactive use z J.C.R. Licklider of MIT, proposes a global network of computers L.C.R. Licklider & W. Clark, "On-Line Man Computer Communication", August 1962. A globally interconnected set of computers through which everyone could quickly access data and programs from any site z Moves to the Advanced Research Projects Agency (ARPA) late in 1962 Lobbies to realize his vision Licklider As Visionary: 11 Man-Computer Symbiosis (1960)… … is an expected development in cooperative interaction between men and electronic computers. The main aims are 1. to let computers facilitate formulative thinking as they now facilitate the solution of formulated problems, and 2. to enable men and computers to cooperate in making decisions and controlling complex situations without inflexible dependence on predetermined programs. 12 Technology Push z 1962: Paul Baran Commissioned by the U.S. Air Force to study how it could maintain command and control over its missiles and bombers after a nuclear attack Invents packet switching ideas (but talks about a “Distributed Adaptive Message Block Network”) z 1961-65: Leonard Kleinrock (MIT Æ UCLA) Develops the theory of packet switching z 1965: Donald Davies in the UK Independently invents packet switching, & coins the term “packet” 13 Baran (1964) z There is an increasingly repeated statement made that one day we will require more capacity for data transmission than needed for analog voice transmission. If this statement is correct, then it would appear prudent to broaden our planning consideration to include new concepts for future data network directions. Otherwise, we may stumble into being boxed in with the uncomfortable restraints of communications links and switches originally designed for high quality analog transmission. New digital computer techniques using redundancy make cheap unreliable links potentially usable. A new switched network compatible with these links appears appropriate to meet the upcoming demand for digital service. This network is best designed for data transmission and for survivability at the outset. 14 Baran (1964) z The requirements for a future all-digital-data distributed network which provides common user service for a wide range of users having different requirements is considered. The use of a standard format message block permits building relatively simple switching mechanisms using an adaptive store-and-forward routing policy to handle all forms of digital data including "real-time" voice. This network rapidly responds to changes in the network status. Recent history of measured network traffic is used to modify path selection. Simulation results are shown to indicate that highly efficient routing can be performed by local control without the necessity for any central--and therefore vulnerable--control point. 15 Baran’s Proposal: A Packet Switched Network “Packet switching is the breaking down of data into datagrams or packets that are labeled to indicate the origin and the destination of the information and the forwarding of these packets from one computer to another computer until the information arrives at its final destination computer. This was crucial to the realization of a computer network. If packets are lost at any given point, the message can be resent by the originator.” 16 Packet Switching z Basic idea Data to be transmitted is divided into small packets of information and labeled to identify the sender and recipient Sent over a network and then reassembled at their destination If any packet did not arrive or was not intact, original sender requested to resend the packet z Note that this implies (relative to circuit switching) Less state at intermediate nodes More flexibility in end system behaviors More efficient use of networks More sophistication at end points 17 The Importance of Technology Trends z Packet switching was arguably a logical consequence of Moore’s law z Computers became fast enough to enable “smart terminals” able to perform substantial processing 18 Theoretical Underpinnings “Packet switching was new and radical in the 1960s. In order to plan to spend millions of dollars and stake my reputation, I needed to understand that it would work. Without Kleinrock’s work on Networks and Queuing Theory, I could never have taken such a radical step. All the communications community argued that it couldn’t work. This book was critical to my standing up to them and betting that it would work.” Larry Roberts 19 1969 Press Release: “UCLA to be the First Station in Nationwide Computer Network” "As of now, computer networks are still in their infancy," says Dr. Kleinrock. "But as they grow up and become more sophisticated, we will probably see the spread of 'computer utilities' which, like present electric and telephone utilities, will service individual homes and offices across the country.” 20 History of the Internet z 1968: ARPA awarded the ARPANET contract to BBN. BBN had selected a Honeywell minicomputer as the base on which they would build the switch. The physical network was constructed in 1969, linking four nodes: University of California at Los Angeles, SRI (in Stanford), University of California at Santa Barbara, and University of Utah. The network was wired together via 50 Kbps circuits. Backbones: 50Kbps ARPANET - Hosts: 4 z 1972: First e-mail program created by Ray Tomlinson of BBN. ARPANET used the Network Control Protocol or NCP to transfer data. This allowed communications between hosts running on the same network. Backbones: 50Kbps ARPANET - Hosts: 23 z 1973: Development began on the protocol to be called TCP/IP, by a group headed by Vint Cerf from Stanford and Bob Kahn from ARPA. This new protocol was to allow diverse computer networks to interconnect and communicate with each other. Backbones: 50Kbps ARPANET - Hosts: 23+ History of the Internet 21 z 1974: First Use of term Internet by Vint Cerf and Bob Kahn in paper on Transmission Control Protocol. Backbones: 50Kbps ARPANET - Hosts: 23+ z 1976: Dr. Robert M. Metcalfe develops Ethernet, which allowed coaxial cable to move data extremely fast. This was a crucial component to the development of LANs. The packet satellite project went into practical use. SATNET, Atlantic packet Satellite network, was born. UUCP (Unix-to-Unix CoPy) developed at AT&T Bell Labs and distributed with UNIX one year later. DOD began to experiment with the TCP/IP protocol and soon decided to require it for use on ARPANET Backbones: 50Kbps ARPANET, plus satellite and radio connections - Hosts: 111+ History of the Internet 22 z 1979: USENET (the decentralized news group network) created: based on UUCP. BITNET introduced the "store and forward" network, used for email and listservs. Backbones: 50Kbps ARPANET, plus satellite and radio connections - Hosts: 111+ z 1981: NSF created backbone called CSNET 56 Kbps network for institutions without access to ARPANET. Backbones: 50Kbps ARPANET, 56Kbps CSNET, plus satellite and radio connections - Hosts: 213 z 1983: Internet Activities Board (IAB) created. On January 1st, every machine connected to ARPANET had to use TCP/IP. TCP/IP became the core Internet protocol and replaced NCP entirely. University of Wisconsin created Domain Name System (DNS), which translated domain names into corresponding IP numbers. No need to remember numbers! Backbones: 50Kbps ARPANET, 56Kbps CSNET, plus satellite and radio connections - Hosts: 562 23 Process and Governance z A key to the rapid growth of the Internet has been the free and open access to the basic documents, especially the specifications of the protocols “Request for Comments” (RFC) documents z “Rough Consensus and Running Code” Frequent face-to-face meetings Heavy use of email Emphasis on implementation experiences 24 RFCs: For Example … RFC: 791 INTERNET PROTOCOL DARPA INTERNET PROGRAM PROTOCOL SPECIFICATION September 1981 This document specifies the DoD Standard Internet Protocol. This document is based on six earlier editions of the ARPA Internet Protocol Specification, and the present text draws heavily from them.
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