Transcript IRIS Project - Massachusetts Institute of Technology

Computer Networks
6.829 Fall 2005
September 8, 2005
nms.csail.mit.edu/6.829
Muscle-Powered Communications
• Human messengers on foot or horseback
• “Command and Control” between capital and
the field
• 14 AD: Roman relays—50 miles per day for
regular mail, 100 miles per day for express
mail
• 1280 AD: Kublai Khan—200-250 mi per day
“Poste Haste”— “Fast Post” —riders signal by
horns
“Let us turn now to the system of post-horses by which the
Great Khan sends his dispatches. You must know that the
city of Khan-balik is a centre from which many roads radiate
to many provinces, one to each, and every road bears the
name of the province to which it runs. ... When one of the
Great Khan's messengers sets out along any of these roads,
he has only to go twenty-five miles and there he finds a
posting station, which in their language is called yamb and
in our language may be rendered as 'horse post'. … Here the
messengers find no less that 400 horses, stationed here by
the Great Khan's orders and always kept in readiness for his
messengers …
"By this means the Great Khan's messengers travel throughout
his dominions and have lodgings and horses fully accoutred
for every stage. … The whole organization is so stupendous
and so costly that it baffles speech and writing.”
-- Marco Polo (1290)
The Pony Express
1861 AD: The Pony Express
• 150-200 mi/day, 1966 mi from
Missouri to California, 10-13 days
• Longest ride: 14 year old
“Buffalo Bill” Cody, 384 mi
• Record time: 7 days 17 hours
with President Lincoln’s
Inaugural Address, March 4, 1861
Western Union’s line puts it
out of business, October 1861
Visual communications: The optical telegraph
Pics: Proc. Symp. on
the Optical Telegraph,
Stockholm, June ’94
• Chappe (1763-1805), a “defense contractor”; 1st message successfully sent in 1794
• 1799: Napoleon seizes power; sends “Paris is quiet, and the good citizens are
content.”
• 1814: Extends from Paris to Belgium & Italy
• 1840: 4000 miles, 556 stations, 8 main lines, 11 sublines, each hop ~10 km
• Many “advanced” techniques: switching, framing, codes, redundant relays, message
acks, priority messages, error notification, primitive encryption!
Scientific Advances
• Late 18th—Early 19th Century
• Increasing evidence of the close relationship
between electricity and magnetism
• Oersted (Copenhagen): demonstrated
electricity’s ability to deflect a needle
• Sturgeon (London), 1825: electromagnet demo
• Joseph Henry, 1830: 1-mile demo: current
through long wires, causing bell to ring!
• Faraday (London), 1831: EM induction
experiments (induction ring), basis for motors
The Electric Telegraph
• Cooke and Wheatstone,
Railroad Telegraph, 1837
• 14 mi installed by 1838
• 4000 mi by 1852
The Electric Telegraph (Samuel Morse)
Morse Code (18351837)
• 1838: demo’d over
2 miles
• 1844: USsponsored
demonstration
between Baltimore
and Washington DC
Dots and Dashes Span the Globe
• 1852: First international
telegram
• Reuters establishes
“Telegraph News Network”
• 1858: Cyrus Field lays first
transatlantic cable
• US President & Queen Victoria
exchange telegrams
• Line fails in a few months
• 1866: New cable &
technology developed by
William Thompson (Lord
Kelvin)
Dots and Dashes Span The Globe
• Communications “arms” race in the Imperial
Age
• No nation could trust its messages to a foreign
power
• 1893: British-owned Eastern Telegraph Company
and the French crisis in Southeast Asia
• 1914: British cut the German overseas cables
within hours of the start of WW I; Germany
retaliates by cutting England’s Baltic cables and
the overland lines to the Middle East through
Turkey
• Strategic necessity: circumventing the
tyranny of the telegraph lines owned by
nation states
Wireless!
James Clerk Maxwell (1831-1879)
"... we have strong reason to conclude
that light itself -- including radiant heat,
and other radiations if any -- is an
electromagnetic disturbance in the form
of waves propagated through the
electromagnetic field according to
electromagnetic laws." Dynamical Theory
of the Electromagnetic Field, 1864.
Heinrich Hertz (1857 - 1894)
• Mid-1880s: Demonstrated experimentally
the wave character of electrical
transmission in space
Wireless Telegraphy
Guglielmo Marconi
• 1895: 21 year-old demonstrates
communication at distances much
greater than thought possible
• Offers invention to Italian
government, but they refuse
• 1897: Demonstrates system on
Salisbury Plain to British Royal
Navy, who becomes an early
customer
• 1901: First wireless transmission
across the Atlantic
• 1907: Regular commercial service
commenced
Wireless in Warfare
“Portable” radio, circa 1915
Airborne radio telephone,
post WW I
The Telegraph Learns to Talk
• Morse telegraph: no multiplexing
• Only one message sent/received at a time
• Second half of 19th century: many
researchers work on improving capacity
• One idea: sending messages at different
pitches (Graham Bell)
The Telephone
Alexander Graham Bell
• 1876: Demonstrates the telephone at US
Centenary Exhibition in Philadelphia
• Bell and Elisha Gray rush patents to USPTO,
Bell first by a few hours
• Bell offers to sell patents to Western Union
for $100,000, who refuse. Bell Telephone
Company founded 9 July 1877.
• 1878: Western Union competes using rival
system designed by Thomas Edison and
Elisha Gray. Bell sues and wins.
Bell’s Early Telephones + “Most Valuable Patent”
US Patent 174,465
(March 7, 1876)
Mechanical Telephone Switch
Almon Brown Strowger (1839 - 1902)
• 1889: Invents the “girl-less, cuss-less”
telephone system
“Ma Bell” and the telcos.
• Bell’s patents expire in 1890s; over 6000
independent operators spring up
• 1910: Bell System controls 50% of local telephone market
• 1913: AT&T & U. S. government reach Kingsbury
Agreement: AT&T becomes regulated monopoly while
promising "universal" telephone service; Controls “toll”
services in U.S.
• Long distance interconnection withheld as a competitive weapon
• 1950: Bell System controls 84% of the local telephone
access market
• 1984: Divesture of Ma Bell (Judge Greene)
• 1996: Trivesiture of AT&T Bell (AT&T, Lucent, NCR)
• Much activitity, mergers, splits, acquisitions over past 10
years
Computer Comms & Packet Switching
ARPA: 1957, in response to Sputnik
Paul Baran
• Early 1960s: New approaches for
survivable comms systems; “hot
potato routing” and decentralized
architecture, 1964 paper
Donald Davies, early 1960s
• Coins the term “packet”
Len Kleinrock (MIT thesis):
“Information flow in large
communication nets”, 1961
J. Licklider & W. Clark (MIT), On-line
Man Computer Communication
L. Roberts (MIT), first ARPANET plan
for time-sharing remote
computers, SOSP ‘67 paper
ARPANET & Internetworking
ARPANet
• 1967: Connect computers at key
research sites across the US
using pt-to-pt telephone lines
• Interface Message Processors
(IMP) ARPA contract to BBN
• Ted Kennedy telegram on BBN
getting contract
BBN team that implemented
the interface message processor
ARPANET Topology in 1969
First inter-site demo, 1969.
First crash very soon after!
History, contd.
• 1970, ARPANET hosts start using NCP; first two crosscountry lines (BBN-UCLA and MIT-Utah)
History, contd.
• 1972, modified ARPANET email program
(BBN), various demos and apps; CYCLADES
effort in France; telnet spec
• 1973, APRANET becomes international
• 1973-75, internetworking effort (Kahn &
Cerf, et al.)
• 1976, UUCP distributed by AT&T
• 1978, TCP and IP split (end-to-end principle)
• 1980, ARPANET grinds to halt due to a virus
History, contd.
• 1981, many networks (BITNET, CSNET,
Minitel, …)
• 1982, DoD standardizes on TCP/IP
• 1984, DNS introduced
• 1986, NSFNet started, NNTP, MX records, big
outage in New England
• Congestion collapse episodes, Van Jacobson’s
solutions
• Decentralized administration
Some Decentralized Administration
(1987)
History, cont.
• 1990, No more ARPANET
• 1991, WWW (Berners-Lee)
• 1990s: everyone gets on the web
• mid-1990s: NSFNet gets out of centralized
backbone; ISPs take off
• 1996, telcos ask for IP phones to be banned,
bubble starts
• 2001, bubble bursts; much progress in
between!
• 2000s: net truly international; more non-PC
devices than computers on the Internet
Year 2000
Internet hosts (names) with time:
~40% per year
The Big Challenges
• Internetworking: interconnecting in the face
of
• Heterogeneity
• Scale
• Generality of uses
• Sharing
• Wireless and mobility
• Handling and facilitating evolution:
expanding the net toward new uses
• Coping with abuses
Normalized Growth since 1980
d(technology)/dt for networks
1,000,000
Highest Link Capacity
2x / 7 months
100,000
# Internet hosts
2x / 13.3 months
10,000
Aggregate Internet Traffic
2x / 12 months
1,000
100
10
Moore’s Law
2x / 18 months
Bits/s per dollar
2x / 79 months
(crude estimate)
DRAM
Access Time
1.1x / 18months
Speed of light
0x / 18 months!
1
1980
1983
1986
1989
1992
1995
1998
Thanks to Nick Mckeown @ Stanford for some of these data points
2001
Acknowledgments
• Professor Randy Katz, UC Berkeley, for
several of these slides
• Professor Nick McKeown, Stanford, for
some data (tech trends)
• Various Web sites, including
about.com, zakon.org, isc.org