Download Lecture 1 - Project Open

History & Technologies of the Internet
Lecture 1 – September 22, 2016
―Lincoln Towers University‖
Sept. 22 – Oct. 13, 2016
Thursdays 7:30-9 pm, 150 WEA Community Room
Instructor: Stephen Weinstein
[email protected], (646) 267-5904
Lecture notes posting site:
projectopenlincolntowers.org/lincolntowersuniversity
Your instructor
A mostly retired engineer living in Lincoln Towers, with a
PhD in electrical engineering from U.C. Berkeley and
extensive experience in the communications industry. I am
a member of the Boards of the 150WEA Owners Corp. and
of Project Open*. My consulting website, cttcservices.com,
has further personal background information.
*I maintain the Project Open web site, projectopenlincolntowers.org
Goals of this course
1. Provide an intuitive explanation, not requiring an
engineering or computer science background, of
-Internet history
-The technical foundations of the Internet
-Relevant basic concepts of communications and
information technology.
2. Answer your questions. Don’t be afraid to ask!
Please have confidence in yourself to understand
basic technical concepts!
Important note:
This is not a course on how to use computers and Internet
services. It is a course on how the Internet came to be,
what it is, and from a science and engineering perspective,
how it works.
Topics Covered in Four Lectures
Lecture 1: Internet background and Digital Media
-Definitions of a few basic terms (data, digital, bit, packet &
packet switching, network, protocol).
-Internet definition and organizations.
-Internet history (and more in future classes).
If there is time, we may introduce digital media, but this will probably
be left to Lecture 2.
Lecture 2: Digital Media and Communications
-Basic concepts: frequency, wavelength, bandwidth &
data rate.
-History of digital/data and wireless communication.
-Why digital? - and how conventional analog media (voice,
images, video) are converted to digital.
-Modulation and modems.
-The different kinds of communication networks supporting
the Internet; protocol stacks.
Lecture 3: Internet architecture & technologies
-Internet architecture (routers, domain name service, …).
-Connection-oriented vs. connectionless (datagram).
-The most important communication protocols used in
the Internet: IP, TCP, UDP, and some others.
-Translating a web address (like
projectopenlincolntowers.org) to an IP address.
-Avoiding address depletion.
Lecture 4: Internet applications
-The original application level protocols: ftp, smtp, telnet
-The World Wide Web: History, browsers, and web pages.
-Audio and video streaming, voice over IP.
-Cloud computing.
-Security attacks (e.g., denial of service).
-The Internet of Things.
Lecture 1: Internet background and
digital media
Basic terms.
Internet definition, organizations,
and history.
Digital media.
BASIC TERMS
Data: A set or stream of symbols or numbers that represent
information.
This information can be voice, video, a picture, your tax return virtually any kind of meaningful content.
These days we keep data in digital storage devices such as computer
hard drives and USB memory sticks. The data is in digital format
(described on the next slide).
Digital: Expressed as a group of numbers chosen from
a small set.
We have ten fingers and that is why we use decimal numbers from the
set: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
We represent an integer by multiples of powers of 10.
Example: 14 (decimal) = 1x10 + 4x1
If we had two fingers, like electronic memories, we would use
binary numbers to represent an integer by multiples of powers of 2.
Example: 14 (decimal) is the same as
1110 (binary) = 1x8 + 1x4 + 1x2 + 0x1
14 and 1110 are both digital representations of the same quantity!
Data Stream: A sequence of digital numbers (sometimes
called digital ―words‖) representing an information object
such as a movie.
Example of decimal and binary digital data streams for the same
information:
14 05 12 15 02 …..
1110 0101 1100 1111 0010 …..
Movies streamed from Netflix or other Internet sources come in
binary data streams like that above.
Bit: A quantity of information, equivalent to the information
generated by the toss of an unbiased coin (head or tail).
Byte: 8 bits. Megabyte (MB): A million bits. Gigabyte (GB): a
billion bits.
A bit of information is commonly represented by ―1‖ or ―0‖ rather
than ―head‖ or ―tail‖, which fits nicely into a digital data stream!
We will, in the next class, explain how a speech or video signal can be
represented by a data sequence of bits.
Sound pressure wave in
air (analog)
Analog to digital conversion
A/D
…0111 0000 1101 0100 ...
Network (for data communications):
A set of originating and terminating entities, forwarding
nodes, and the transport links connecting them, for
conveying data traffic.
Terminating device (phone,
computer, cell phone, etc.)
Switch (in traditional telephone network)
or router (in Internet and other packet networks).
Packet:
A data package conveying, through a network, bits
representing part or all of a message.
Complete message (digital data)
A series of packets, each carrying part of the message
It’s a lot like packing a large shipment into a series of trucks
that may possibly be of different sizes.
Packet multiplexing: A mixed stream of packets from
different sources.
The sources are represented here by the numbers 1,2,3,4.
2-voice
1-video
1-video
3-keyboard
1-video
1-video
Packet switching (routing) vs. traditional line switching
at a network node
Line switching:
For a particular information flow for which the entire path through the
network is reserved in advance, a connection is made between the input
line carrying this flow and an output line on the prearranged route.
Packet switching (routing) vs. traditional line switching:
Packet switching, ―datagram‖ model:
Without reserving a route in advance, a particular packet is transferred
to a buffer for an output line that the router selects as the best next
―hop‖. If the buffer is too full, the packet will be discarded.
The Internet implements this ―unreliable‖ routing mechanism, but
with enough capacity, packet discards (or long delays) will be
minimal.
(Communication) protocol:
A formal description of the format and rules for a message exchange.
Several layers of protocols are usually needed to completely specify
an information exchange.
A packet protocol, for example, will specify, in the packet ―header‖,
sending and receiving addresses, information quantity, and
information type.
Simple packet model:
Header
Information field (payload)
Source & destination addresses, etc.
Definitions of an internet and the Internet
An internet (not the Internet) is a combination of several distinct
communication networks capable of conveying data between
endpoints on different networks.
Local Area
Networks
Personal Area
Networks
Satellite
Bluetooth
Infrared
WiFi
Bluetooth
Core
Networks
Access
networks
(IEEE 802.11)
Cellular
mobile
Cable (HFC)
DSL
Ethernet
Optical
fiber
Optical Core Network,
metropolitan & long haul
The Internet is the publicly available combination of multiple distinct
communication networks augmented by the Internet Protocol (IP) and
subscribing to Internet standards in order to convey data through this
multi-network environment.
IP
The Internet is one example of
an internet
Cellular
mobile
WiFi
Bluetooth
Cable (HFC)
Wireless router
IP
Ethernet
Optical
fiber
Domain
Name
Server
Router
Optical Core Network,
metropolitan & long haul
History of the Internet
Donald
Davies
Lawrence
Roberts
Leonard
Kleinrock
J.C.R.
Licklider
Jon
Postel
Paul
Baran
Vinton
Cerf
Robert
Kahn
1961-62: MIT Prof. J.C.R. Licklider envisioned a "Galactic Network"
as a globally interconnected set of computers through which everyone
could quickly access data and programs from any site. Leonard
Kleinrock published first paper on relevant packet switching theory.
Kleinrock message switching1: "Basically, what I did for
my PhD research in 1961–1962 was to establish a mathematical theory of packet
networks...―.
Refs: https://www.internetsociety.org/internet/what-internet/history-internet/brief-historyinternet
1 L. Kleinrock, "Information Flow in Large Communication Nets", MIT RLE Quarterly
Progress Report, July 1961.
Mid 60s: Publications on packet switching from RAND (Paul Baran)
and the National Physical Lab in the U.K. (Donald Davies).
RAND was studying network survivability after nuclear war:
―If war does not mean the end of the earth in a black and white manner, then it
follows that we should do those things that make the shade of grey as slight as
possible: to plan now to minimize potential destruction and to do all those things
necessary to permit the survivors of the holocaust to shuck their ashes and
reconstruct the economy swiftly.‖1
His concept was a distributed system
in which a broken route could
easily be replaced by another.2 He
called it ―hot potato‖ routing or
adaptive ―message block switching.‖
Paul Baran, ―Reliable Digital Communications Systems Using Unreliable Network Repeater Nodes‖, the
RAND Corp. report P-1995, 5/27/60, www.rand.org/content/dam/rand/pubs/papers/2008/P1995.pdf
2 http://www.rand.org/about/history/baran.list.html
1
Donald Davies invented the terms ―packet‖ and ―packet switching‖
and built early experimental packet networks.
He initially worked at the National Physical Laboratory under Alan Turing, the great
pioneer of computing whose WWII work broke the Enigma code and greatly
contributed to the allied victory.
Turing
Davies
NPL
PS: packet switch
UM: User machine (computer)
T: Terminal
TP: Terminal Processor
R. Scantlebury & P. Wilkinson, ―The National Physical Laboratory Communication Network‖,
Proc. ICCC 1974, available at http://rogerdmoore.ca/PS/NPLPh/NPL1974A.html
FUNCTIONS OF A PACKET SWITCH (or ROUTER)
-Routing (which output line is part of the best path to destination?)
-Forwarding (place packet in the waiting line (queue) for the desired
output line.
Incoming packets on
several lines
Outgoing packets on
several lines
Ref: https://www.internetsociety.org/internet/what-internet/history-internet/briefhistory-internet
1968: Lawrence Roberts and colleagues at the U.S. Defense Advanced
Research Projects Agency (DARPA) developed specifications and a
Request for Proposals for the ARPANET, in particular for
development of packet switches called Interface Message Processors
(IMPs).
The RFQ was won by Bolt Beranek and Newman (BBN). The first
IMP was installed at UCLA in 1969.
Bob Kahn:
ARPAnet
architecture
Len Kleinrock:
Network
measurements
Larry Roberts:
Network topology
& economics
Early ARPANET Architecture
HOST - A computer serving as an originating/terminating node.
IMP- Interface Message Processor, a packet switch handling up to
four Hosts and four 50Kbps communications lines, implemented
in a Honeywell DDP-516 minicomputer.
TIP- Terminal Interface Processor, an IMP supporting 64 terminals.
T - Terminal (―dumb‖ personal computer, just keyboard and screen).
Ref: http://nrg.cs.ucl.ac.uk/internet-history.html
IMP
The second node was at Stanford Research Institute (SRI) where Doug
Engelbart’s project on ―Augmentation of Human Intellect‖ included
NLS, an early hypertext system. Engelbart was also the inventor of
the computer mouse.
Knowledge linking, collaborative work, …
Refs:
http://www.internetsociety.org/internet/what-internet/history-internet/brief-history-internet#LK61
http://www.dougengelbart.org/firsts/mouse.html
D. Engelbart, ―Augmenting Human Intellect: A Conceptual framework‖, SRI Rpt. AFOSR-3223,
Oct. 1962, http://www.dougengelbart.org/pubs/augment-3906.html
Why did they want a packet-switching data network rather
than a line switching network like the telephone network?
Resource sharing: Access to distant computers.
Resilience: Ability to reroute packets if a link or node goes down.
This was a major motivation for military networks.
Burst traffic: Ability to convey brief data bursts (like a keyboard
entry) without the delay and complexity of setting up new
switched lines.
Flexibility: Ability to mix different kinds of traffic (computer bursts,
voice, video) at different data rates, across different
networks.
1971-72: Host-to-Host (computer to computer) Network Control
Protocol (NCP). NCP provided connections and flow control between
processes (computer programs) running on different ARPANET host
computers but did not guarantee end-to-end reliability. NCP ran on
top of packet forwarding supplied by the IMP. It was the predecessor
of TCP.
Steve Crocker
S. Crocker, J. Postel, J. Newkirk & M. Kraley, ―An Office Protocol Proffering‖, RFC 54,
June 18, 1970.
Fall 1972: Bob Kahn demonstrates ARPANET services at the
International Conference on Computer Communications
(Washington). I was there. Unfortunately no photos are available.
1973: Vint Cerf and Bob Kahn develop TCP/IP (Transport Control
Protocol / Internet Protocol), a protocol pair supporting routing and
reliable end-to-end connections built on IP’s ―best effort‖ (datagram)
service. Enhanced internetworking across dissimilar networks (Kahn
wanted to add a satellite network).
Originally tightly integrated, TCP and IP were later separated to allow
alternative transport-level protocols. These protocols will be
described in a later lecture.
Cerf and Kahn receiving Presidential
Medal of Freedom, 2006
This paper largely focused on the TCP part, process-to-process connections.
ARPANET geographic map, July, 1976
http://mercury.lcs.mit.edu/~jnc/tech/jpg/ARPANet/G76Jul.jpg
1980: TCP/IP adopted as a defense standard.
1981: Original DARPA protocol standard for IP (RFC 791).
Jan. 1983: ARPANET cutover from NCP to TCP/IP.
1983: MILNET (Military Network) split off from ARPANET.
1986: NSFnet launched by the National Science Foundation, initially
to interconnect supercomputers. Connection to ARPANET makes
packet network more generally available to all academic users.
Ref: https://www.nsf.gov/about/history/nsf0050/internet/launch.htm
http://207.75.117.26/research/nsfnet.php
1987: NSF upgrade solicitation, foreseeing commercial users. IBM,
MCI and a consortium of Michigan universities win contract.
July, 1988: New backbone becomes operational, using 1.5 Mbps
(megabit per second) links. This may be considered the beginning of
the Internet. Demand surges, leading to replacement by 45 Mbps links
in 1991.
Did Al Gore have a role in realization of the Internet?
Yes, indirectly, of part of the modern Internet.
He was prime sponsor of the 1991 High-Performance Computing and
Communications Act which allocated $600 million to the National
Center for Supercomputing Applications among other entities. The
early Mosaic web browser was developed there.
2012, Gore was inducted into the Internet Hall of Fame for being ―a
key proponent of sponsoring legislation that funded the expansion of
and greater public access to the Internet.‖
But he probably shouldn’t have said, in a 1999 interview with Wolf
Blitzer, that ―During my service in the United States Congress, I took
the initiative in creating the Internet.‖
https://www.washingtonpost.com/blogs/fact-checker/wp/2013/11/04/a-cautionarytale-for-politicians-al-gore-and-the-invention-of-the-internet
1989: Tim Berners-Lee invented the World Wide Web while at CERN
(European Nuclear Research Center), mainly to help physicists
exchange information.
World Wide Web technologies (web sites and addresses, hypertext
description language, …) will be explained in Lecture 4.
Tim Berners-Lee
Early web browser
28 Feb. 1990: ARPANET formally decommissioned. It was not
transformed into the Internet; they were different entities with the
Internet inheriting technical concepts from ARPANET.
1991: NSF lifts ban on commercial use of NSFnet, effectively
launching the Internet. Deployment of 45 Mbps links and
establishment of for-profit subsidiary to enable commercial
development of the network. NSF Backbone carrying 17.8 trillion
bytes per month by end 1994.
Internet Service Providers (ISPs), providing dial-up access to the
Internet for consumers, began to appear, some extensions of earlier
on-line content providers, including:
CompuServe, BIX, AOL, DELPHI, Prodigy, UUNET, The Pipeline,
Panix, Netcom, the World, EarthLink, and MindSpring
1993: My wife, Judy, and I, together with several Bellcore, NJ Bell
and Morris County Information Network colleagues, launch
MORENET, second only to Seattle in providing Internet access to
public libraries including dialup from home.
http://mclib.info/wp-content/uploads/2015/06/timeline.pdf
April, 1995. NSFNET backbone defunded, opening the Internet to
full commercial use. NSF funding was $200 million from 1986 to
1995.
Regional networks now bought national-scale Internet connectivity
from various long-haul network providers.
Some additional Internet pioneers:
Robert Taylor
Directed ARPA’s computer research program in 1960s, initiated
ARPAnet project 1966, coauthored influential paper ―The
Computer as a Communication Device‖ with J.C.R. Licklider
Paul Mockapetris, along with Jon Postel, designed
and developed DNS, the domain name architecture
translating a URL into an IP address.
David Clark
Chairman of the Internet Activities Board in the 1980s, he was the
Chief protocol architect and developer of operating rules.
Elizabeth Feinler
Managed network information center (NIC) of the ARPANET, under
contract to DoD. Her group developed early address servers and
Host Naming Registry. She and her group developed the top-level
domain-name scheme (.com, .edu, .gov, .mil, .org, and .net).
Deborah Estrin
In early-mid 1990s, made important contributions to Internet routing.
Steve Wolff
As Division Director for Networking at the National Science
Foundation (NSF) in the 1980s, he was responsible for the
development of the NSFNET
Lixia Zhang
Cofounder of the Internet Engineering Task Force, designed the
Resource Reservation Protocol in the 1990s.
Stephen Deering
Designed the multicast extension to the Internet Protocol (IP) and
was principle architect of the latest version of IP, IPv6, with its
immensely larger address pool.
Ref: http://www.zakon.org/robert/internet/timeline/
Internet Organizations
NTIA
Nat. Telecommun. &
Infor. Administration
ISOC
Internet Society
IETF
Internet Engineering
Task Force
ICANN
Internet Corporation
for Assigned Names
& Numbers
IANA functions
Internet Assigned
Numbers Authority
IESG
IAB
Internet Engineering
Steering Group
Internet Architecture
Board
[Functions on next several slides]
ISOC (Internet Society)
The parent organization, formal or informal, of the Internet
management bodies
IETF (Internet Engineering Task Force)
―The Internet Engineering Task Force (IETF) is a large open
international community of network designers, operators, vendors, and
researchers concerned with the evolution of the Internet architecture
and the smooth operation of the Internet. It is open to any interested
individual. ―
http://www.ietf.org/old/2009/overview.html
Draws up RFCs (Requests for Comments), mostly proposals for
enhancing Internet technologies and capabilities, that may or may not
be adopted as Internet standards. Administered for
many years by the famous packet networking
pioneer, Jon Postel.
RFC example: The original Internet Protocol
RFC: 791
INTERNET PROTOCOL
DARPA INTERNET PROGRAM
PROTOCOL SPECIFICATION
September 1981
prepared for
Defense Advanced Research Projects Agency
Information Processing Techniques Office
1400 Wilson Boulevard
Arlington, Virginia 22209
by
Information Sciences Institute
University of Southern California
4676 Admiralty Way
Marina del Rey, California 90291
https://tools.ietf.org/rfc/rfc791.txt
IAB (Internet Architecture Board)
Architectural Oversight of protocols and procedures used by the
Internet.
Standards Process oversight and appeal
Editorial management and publication of the Request for Comments
(RFC) document series, and for administration of IANA assignments.
IESG (Internet Engineering Steering Group)
The major review body for standards. Responsible for technical
management of IETF activities and the Internet standards process,
specifically for the actions associated with entry into and movement
along the Internet "standards track," including final approval of
specifications as Internet Standards.
Ref. for standards process: https://www.ietf.org/rfc/rfc2026.txt
ICANN (Internet Corporation for Assigned Names and Numbers)
Administers the IANA (Internet Assigned numbers Authority)
functions of IP address space allocation, protocol parameter
assignment, domain name system management, and root server system
management functions. Jon Postel created this vital activity in the
1970s, as well as administering the RFCs.
Example of an IP address:
projectopenlincolntowers.org -----> 216.119.141.194
Currently, stewardship is being passed from the U.S. Government's
National Telecommunications and Information Administration (NTIA)
―to the global, multi-stakeholder community.‖
Ref: http://www.internetsociety.org/ianaxfer
Washington Post
U.S. to relinquish remaining control over the Internet
By Craig Timberg March 14, 2014
U.S. officials announced plans Friday to relinquish federal government control
over the administration of the Internet, a move that pleased international critics
but alarmed some business leaders and others who rely on the smooth functioning
of the Web.
Pressure to let go of the final vestiges of U.S. authority over the system of Web
addresses and domain names that organize the Internet has been building for more
than a decade and was supercharged by the backlash last year to revelations about
National Security Agency surveillance.
The change would end the long-running contract between the Commerce Department
and the Internet Corporation for Assigned Names and Numbers (ICANN), a California-based nonprofit group. That contract is set to expire next year but could be
extended if the transition plan is not complete.
https://www.washingtonpost.com/business/technology/us-to-relinquish-remaining-controlover-the-internet/2014/03/14/0c7472d0-abb5-11e3-adbc-888c8010c799_story.html
Trump Weighs In on Internet Fight in Stopgap Spending Bill
By THE ASSOCIATED PRESS, SEPT. 21, 2016, 6:25 P.M. E.D.T.
WASHINGTON — Donald Trump's campaign has inserted itself into already
tricky negotiations on a temporary spending bill needed to avert a government shutdown, siding with Texas Sen. Ted Cruz in trying to block the government
from ceding its limited role in overseeing some aspects of the internet.
"Donald J. Trump is committed to preserving Internet freedom for the American
people and citizens all over the world. The U.S. should not turn control of the Internet
over to the United Nations and the international community," senior Trump adviser
Stephen Miller said in a statement.
Democratic and Republican administrations have both supported a transition of the
U.S. Commerce Department's role in governing the internet's domain name addressing
systems, transferring responsibility to such stakeholders as technical experts,
businesses and other governments
http://www.nytimes.com/aponline/2016/09/21/us/politics/ap-us-congress-rdp.html
The next three lectures: The Internet’s Three
Technical Foundations
-Digital Media, Communications (September 29)
-Internet-Specific Technologies:
Architecture, Protocols and Applications (Oct. 6 & 13)