Transcript Internet History - Physics, Computer Science and Engineering

Internet History
What is the Internet?
Where did it originate?
How did it evolve?
Objectives
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Review some of the basic terminolgy.
Look at the historical evolution of the
internet.
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Identify some of the major subnets.
Advanced Research Projects Agency
(ARPA) of the U.S. Dept. of Defense
(DOD)
Need: In the Cold War Era of the 50s and 60s DOD
needed command and control nets which were
decentralized and capable of surviving direct hits
on centers yet have surviving nodes remain
operational.
Initially built to provide a platform which would
allow for remote login to fast computers and
save expense of additional computers.
ARPANET
• served as the experimental platform for
many of the protocols which were tested
and for developing the concepts of layered
protocols
• first installed in 1969
• Initially it did not employ TCP/IP , but
used Network Control Protocol (NCP).
Packet Routing approaches
• Circuit switched
• Packet Switched
– datagram
– virtual circuit
Circuit Switched
• requires a circuit setup
• uses a dedicated connection
• requires reconnection procedure if
connection lost
Packet Switched
• data divided into small packets
• each packet can traverse a different path
• employs intermediate routers to determine
appropriate path
• dedicated computers traditionally served as
the routers
• uses
– datagram
– virtual circuit
Datagram
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each packet individually routed
adaptable (failure or load variation)
connectionless oriented
chose by ARPA & used in IP
Virtual Circuit
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all packets use same route
efficient alloc of resources (buffers..)
connection oriented
implemented over IP by TCP
Basic Components
• link - physical connection
• host - computer connected to network
usually only one connection to the network
• router - computer providing service of
determining where to forward packets
– multiple connections to net
– called InterfaceMessageProcessor (IMP) or
PacketSwitchNode (PSN)
• node - either a router or a host
– each has its own unique addres
History
1977
1983
First implementation of internet
packet satellite
packet radio
ARPANET
Ethernet at XEROX research center
Development of TCP/IP
ARPANET no longer experimental and passed
control to another agency (DCA)
DCA split it into
ARPANET for continued research and
MILNET
2 early transcontinental national backbones
History
Other agencies joined and name changed from
ARPA Internet to Federal Research Internet to
TCP/IP Internet to Internet
1984 NSF established office for networking
1986 (56Kbps) 1988 (1.544Mbps) 1990 (45Mbps)
also provided seed money for NSF regional nets
for education, gov. agencies and commercial business
now self supporting
Other Networks (not internet)
1981
1981
1989
1978
1979
1983
CSNET (Computer Science Network)
functionally provided only email
used dial-up services
BITNET (Because It’s Time Network)
mostly educational for computer center
part of IBM VM/370 os
CSNET and BITNET merge under mgmt
or CREN (Corporation forResearch & Education Networking)
BITNET absorbed CSNET. BITNET being
absorbed into Internet.
UUCP mail net. dialup service for mail delivery
USENET (Users’ Network) for providing a news
service and IS A SERVICE not a net. Originally
on UUCP, now on most nets including Internet
FidoNet connects MSDOS machines (like UUCP)
Now integrated with Internet. (Internet backbone for BITNET)
Still have limited direct function of mail/news, some file xfer.
Reasons for growth
Implementation of TCP/IP in 4.2BSD in 1983 at
Univ of Cal at Berkley (UCB) by its
Computer Systems Research (CSRG).
Public funding dictated it be made available at cost.
Lots of startup companies used it.
Inexpensive Microprocessors
Inexpensive wide-area fiber optic bandwidth
NSFNET regional networks
DNS for domain name service
Responsibility
Decentralized
Internationally handled in a variety of ways
In U.S., the NSF has the leading role in setting policy.
Individual organizations can set their own policies.
Many organizations participate in Federal Networking Council
(FNC) (govt)
NSFNET is largest. About a dozen regionals and thousands of
connections to each of those exist.
Successor to NSFNET is
National Research and Education Network (NREN)
created by High Perf Computing Act of 1991
International level of organization is loosely structured. Each
country/local area manages its own. Some countries have
regional orgs (European Commission).
API
Applications Progamming Interface
• Procedure calls to access this functionality
– Not a protocol!
• Examples
 Berkley sockets (WE WILL USE THIS)
 TLI (Transport Layer Interface)
 XTI (X/Open Transport Interface)
 Winsock (windows 95/98/…)
 RCP (remote procedure calls)
 POSIX compliance is an attempt to make calls the
same from code for ALL OSs. Standards for
Protocol Independent Interface (PII) being
developed for POSIX compliance.
Specifications
• Internet Drafts
– First circulated for discussion.
– Online for only 6 months.
– When/if it becomes an RFC it is removed.
• RFC (Request For Comment)
– More formal proposal for a standard.
– Multiple and even subsequent RFCs associated
with STD
• STD (Internet Standards)
– Set required and optional feature support.
– One standard might be optional but if adopted
would require other standards be adhered to.
Standards Bodies
• ISOC (Internet Society)
– International, Non-profit
– Appears to be responsible for electing/selecting
– members of following bodies, but not clear
• IAB (Internet Architecture Board)
– Recommending body
– Chair elected from members and Chair selects
members
Standards Bodies
• IETF (Internet Engineering Task Force)
– Originates all technical work
– Sets up working groups for seeking a goal in
one of the areas
• applications, internet, net mgmt, operational reqs,
service appllications, routing, security, stds mgmt,
transport, user services
• IRTF (Internet Research Task Force)
– areas where outcomes are uncertain but related
to internet’s future