Genghis Khan’s Empire at His Death at 1227
Hui Zhang, Fall 2012
1
Early Communication over Long
Distance
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Between human beings
Letter and messenger
- Information carried by physical objects
- Speed limited by transportation means: horse, bird,
train, car
- Bandwidth? distance? security?
Fire
- Early optical communication
- Speed of light
- Bandwidth? distance? security?
Hui Zhang, Fall 2012
2
Transcontinental Railroad: 1869
Hui Zhang, Fall 2012
3
Telegraph: Communication Using
Electrons
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Between human beings
Major milestones:
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1827: Ohm’s Law
1837: “workable” telegraph invented by Samuel Morse
1838: demonstration over 10 miles at 10 w.p.m
1844: Capitol Hill to Baltimore
1851: Western Union founded
1868: transatlantic cable laid
1985: last telegraph circuit closed down
Hui Zhang, Fall 2012
4
Telegraph Engineering
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Technical issues
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How to encode information?
How to feed/input information to the system?
How to output information?
How to improve the distance?
How to improve the speed?
How to improve the simultaneous # of telegraphs?
Common issues faced by all telecommunication
systems
Hui Zhang, Fall 2012
5
Telephony Milestones
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1876: Alaxendar Bell invented telephone
1878: Public switches installed at New Haven and San
Francisco, public switched telephone network is born
• People can talk without being on the same wire !
Without Switch
Hui Zhang, Fall 2012
With Switch
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Telephony Milestones
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1878: First telephone directory; white house line
1879 Patent settlement between West Union and Bell
1881: Insulated, balanced twisted pair as local loop
1885: AT&T formed
1892: First automatic commercial telephone switch
1903: 3 million telephones in U.S.
1915: First transcontinental telephone line
1927: First commercial transatlantic commercial service
Hui Zhang, Fall 2012
7
Telephony Milestones
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1937: Multiplexing introduced for inter-city calls
Without Multiplexing
Hui Zhang, Fall 2012
With Multiplexing
8
Telephony Technology Milestones
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Encoding technology
- 1939: Pulse Code Modulation (PCM) invented
Basic technology
- 1948: Transistor invented by Bell scientists
Automation
- 1951: Direct dialing for long-distance demonstrated
Transmission technology
- 1963: Digital transmission introduced
- 1983 First fiber-optic cable in ATT long distance network
Switching technology
- 1965 1ESS central office switch introduced
• Stored Program Control (computerized)
- 1976 4ESS: first digital electronic switch
- Hui
1999
4ESS switch installed in ATT network
Zhang, FallLast
2012
9
End Device Evolution
Hui Zhang, Fall 2012
10
Switch Evolution
1ESS
4 ESS
Early Phone
Switch Center
Hui Zhang, Fall 2012
Cisco Router
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History of the Internet
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70’s: started as a research project, 56 kbps, < 100
computers
80-83: ARPANET and MILNET split
85-86: NSF builds NSFNET as backbone, links 6
Supercomputer centers, 1.5 Mbps, 10,000 computers
87-90: link regional networks, NSI (NASA), ESNet(DOE),
DARTnet, TWBNet (DARPA), 100,000 computers
90-92: NSFNET moves to 45 Mbps, 16 mid-level networks
94: NSF backbone dismantled, multiple private backbones
Today: backbones run at 10 Gbps, hundreds of millions
devices around the world
Hui Zhang, Fall 2012
12
Topology of ARPANet
56 Kbps
Hui Zhang, Fall 2012
13
Devices of ARPANet
Backplane
PDP-10
Hui Zhang, Fall 2012
IMP
14
End Device Evolution
Computer
Without
Network
Hui Zhang, Fall 2012
15
Today’s Internet End Devices
Hui Zhang, Fall 2012
16
Network Evolution
Hui Zhang, Fall 2012
17
Commercial Internet after 1994
Joe's Company
Campus Network
Berkeley
Stanford
Regional ISP
Bartnet
Xerox Parc
SprintNet
America On Line
UUnet
NSF Network
IBM
NSF Network
Modem
AT&T
IBM
Hui Zhang, Fall 2012
18
A Taxonomy of Communication
Networks
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Communication networks can be classified based on
the way in which the nodes exchange information:
Communication
Network
Switched
Communication
Network
Circuit-Switched
Communication
Network
Broadcast
Communication
Network
Packet-Switched
Communication
Network
Datagram
Network
Hui Zhang, Fall 2012
Virtual Circuit Network
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What is a Communication Network?
(from end-system point of view)
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Network offers a service: move information
- Bird, fire, messenger, truck, telegraph, telephone, Internet …
- Another example, transportation service: move objects
• Horse, train, truck, airplane ...
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What distinguish different types of networks?
- The services they provide
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What distinguish the services?
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Latency
Bandwidth
Loss rate
Number of end systems
Service interface
Other details
• Reliability, unicast vs. multicast, real-time, message vs. byte ...
Hui Zhang, Fall 2012
20
What is a Communication Network?
Infrastructure Centric View
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Electrons and photons as communication medium
Links: fiber, copper, satellite, …
Switches: electronic/optic, crossbar/Banyan
Protocols: TCP/IP, ATM, MPLS, SONET, Ethernet, X.25, FrameRelay,
AppleTalk, IPX, SNA
Functionalities: routing, error control, flow control, congestion control,
Quality of Service (QoS)
Applications: telephony, FTP, WEB, X windows, Search, Youtube,
Facebook ...
Hui Zhang, Fall 2012
21
Summary
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Communication long before computer
Evolutions of modern communication and computer
intertwined
Component centric view
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End devices (telephone, computer, smartTV)
Switch (analog vs. digital, circuit vs. packet)
Transmission (copper, fiber, wireless)
Protocol (TCP/IP, Ethernet, ATM, WiFi)
Service centric view
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Service interface (bytestream vs. datagram, SOAP vs. REST)
Performance: reliability, latency, throughput
Security
Point to point vs. multicast vs. broadcast
Hui Zhang, Fall 2012
22
Key Drivers for Computer Networks
Evolution
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Computers and other smart devices
Routers/switches
Transmission technologies
- vDSL, DWDM, WiFi, WiMax, 4G
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Applications
- telnet, FTP, Web, e-commerce, social, search, voice, video,
gaming, etc …
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Software
- Distributed control software for the infrastructure
(switching/routing protocols, DNS, CDN)
- End device software
- Server software
- Application software (device, cloud)
Hui Zhang, Fall 2012
23
Other Key Aspects of The Most
Important Global Infrastructure
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Dependability, security, and manageability
Industry structure and regulation
Global politics
Hui Zhang, Fall 2012
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