Transcript CS 428 Notes 1

Motivation for
Internetworking
• Most networks are independent
entities
• Networking is old idea
• Internetworking is more than 25
years old
– Heterogeneous interconnect
networks
– Network hardware details hidden
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Open Systems
Interconnection
• Open System = Publicly
available specifications
• Proprietary Communication
systems = One vendor, selfserving
• Our network benefits from OSI
standards
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OSI Why?
• “More importantly, the entire
technology has been designed to
foster communication between
machines with diverse hardware
architectures, to use almost any
packet switched network
hardware, and to accommodate
multiple computer operating
systems.” Doug Comer, page 1
• Would that the world were so
were so facile.
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TCP/IP Internet
• Advanced Research Projects
Agency (ARPA)
– Defense Advanced Research
Projects Agency (DARPA) in
mid-80’s
• ARPA technology defines a set
of network standards that
specify how computers
communicate
• Set of conventions for
interconnecting and routing
• At one point, all addresses were
kept in a single file
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TCP/IP
• Standards & conventions called
Protocols
• TCP/IP is a blend of
Transmission Control Protocol
and Internet Protocol
• TCP/IP Internet Protocol Suite
• Across any set of
interconnected networks
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TCP/IP
• Forms base for a global internet
• An internet = private internets
that use TCP/IP
• The Internet = The Global
Internet
• Many U.S. gov’t agencies have
funded the Internet development
• The ARPA/NSF Internet
– The TCP/IP Internet
– The global Internet
– The Internet
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Application Level
Internet Services
• To user, TCP/IP appears to be a
set of application programs
• Interoperability - the ability of
diverse computing systems to
cooperate in solving
computational problems
• Internet application programs
demonstrate a high degree of
interoperability
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Applications
• Electronic mail
• File transfer
• Remote login
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Network Level Internet
Services
• Programmer’s view provides 2
broad services
• Connectionless Packet Delivery
System
• Reliable Stream Transport
Service
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What Distinguishes
TCP/IP?
• Network Technology
Independence
– Datagram
• Universal Interconnection
– Addresses universally recognized
throughout the Internet
• End to End Acknowledgements
– Others are just between stations
(intermediate routing nodes)
• Application protocol standards
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History & Scope of the
Internet
• ARPA began internet
technology in mid-70’s
– Architecture & protocols taking
current form ‘77-’79 (ARPANET)
• Point to Point leased line
interconnection, radio networks,
satellites
• Funding $$$ prevalent in ‘79,
many researchers
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ICCB
• Internet Control and
Configuration Board
• ARPA formed informal
committee to coordinate
– Design of protocols
– Architecture
• Met through about 1983
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Global Internet
• Began around 1980
• ARPA started converting
machines attached to its
research computers with TCP/IP
• ARPANET became the
backbone of new Internet
• January 1983 Office of
Secretary of Defense mandated
that all computers connected to
the long haul network use
TCP/IP
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ARPANET/BSD/BBN
• Split, 1 for research, 1 for military research
• Made ARPANET available to universities
at low cost
• At time, most CS departments were using
Unix
– University of California’s Berkeley
Software Distribution, Berkeley Unix,
BSD Unix
• ARPA funded Bolt Beranek and Newman
(BBN) to implement its TCP/IP protocols
for use with Unix
• ARPA funded Berkeley to integrate the
protocols with its software distribution
• Ergo, ARPA able to reach very high
percentage (90%) of all university CS
departments
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BSD Unix
• Offered a set of networking
functions that resembled Unix
services used on single
machines
• Experienced Unix users have no
problems learning TCP/IP
networking interfaces because
they are so similar
• New operating system
abstraction called the socket
– Allows application programs to
access communications protocols
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Internet Youth
• 1985 - Six supercomputer centers
• 1986 - Expanded to funding wide
area backbone called NSFNET
• Tied above to ARPANET
• NSF in 1986 provided seed money
for regional networks
• All NSF funded networks use
TCP/IP
• 1987 (7 years later) the Internet
spanned hundreds of individual
networks in the U.S. and Europe
• Connected nearly 20.000 computers,
by late 1987 estimate was that the
Internet was growing at 15% per
month
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Internet Teenager
• 1994 - the Internet reached over
3,000,000 computers in 61
countries
• Rapid expansion problems of an
unanticipated scale
• Motivated researchers to find
techniques to manage large,
distributed resources
• Original design
– Names and addresses of all
computers attached to the Internet
were kept in 1 file
– Mid-80’s apparent central data
base not right solution
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Domain Name System
• Name servers answer queries
about name/address pairs
• No single machine contains
entire name base
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Internet Architecture
Board (IAB)
• TCP/IP internet protocol did not
arise from a specific vendor or
from a recognized professional
society
• Who sets the technical
standard?
• The IAB provides focus and
coordination for
–
–
–
–
Research
Development
Guides Evolution
IAB is almost exclusively
volunteers
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IAB Activities
• Formed in 1983 from
reorganized ICCB
• First 6 years, it changed from
ARPA specific to autonomous
organization
• Each member of IAB chaired a
specific Internet Task Force
– Approx. 10 task forces
– Charters from how traffic load
from an application affects the
Internet to short term Internet
Engineering problems
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IAB Activities
• Did not manage a large budget
• Volunteers
• Members responsible for
recruiting volunteers to serve on
task forces
– usually from research
organizations of industry where
TCP/IP was used
• Active researcher participated
because
– Serving on task force allowed
learning about new research
problems
– Could have direct influence on
standards
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IAB ReOrg
• Summer 1989
• Political and Commercial
realities
• Researchers moved from IAB
Board to subsidiary group
• New IAB Board with
representatives from wider
community
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IAB Organization
The Board
IRTF
IETF
IRSG
IESG
area 1
Research Groups
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area n
Working Groups
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