This is a basic presentation regrading APANET

1. The ARPANET
Akhil Kaushik,
Assistant Professor, CSE Deptt
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2. ARPANET
It is abbreviated as “Advanced Research
Project Agency Network”.
In mid 60’s, Department of Defense (DoD)
started ARPANET to build a network that
could resist any attacks from USSR; &
Help academicians (professors & students)
share research.
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3. ARPANET
It was in response to USSR’s Sputnik
launch in 1957.
It connected 4 major universities:
– University of California (@Los Angles)
– University of California (@Berkeley)
– University of Utah
– Stanford Research Institute
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4. ARPANET
ARPANET used the packet-switching
technology to interconnect four nodes.
Hence DoD divided the network into subnets
& host computers.
Subnet would consist of minicomputers called
“Interface Message Processors” (IMPs)
connected by transmission lines.
For high reliability, each IMP would be
connected to atleast 2 IMPs.
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5. ARPANET
Even if some IMPs or lines were damaged, the
network still worked for others.
Each node of the network was to consist of an IMP
and a host, in same room connected by a short wire.
A host could send messages up to 8063 bits to its
IMP, which would break these into packets of atmost
1008 bits and forwards them independently towards
the destination.
Each packet was received fully before forwarding to
next hop.
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6. ARPANET
HOST HOST
IMP
Subnet
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7. ARPANET
The software was needed between IMPs to
provide communication.
Also, software was needed to provide host-
IMP, user-host & host-host communication.
This model of ARPANET expanded to 8
nodes, then 15 nodes and so on expanded to
form today’s Internet.
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8. The Usenet
Akhil Kaushik,
Assistant Professor, CSE Deptt
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9. Introduction
Usenet is a world-wide network of
discussion groups (or news groups).
Usenet is a worldwide distributed Internet
discussion system. It evolved from the
general purpose UUCP architecture of the
same name
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10. What is the USENET?
The Usenet consists of over 30,000 Internet
discussion groups, often called "newsgroups."
The groups are organized by topic, and if you can
think of an interest shared by at least a few people,
there is likely already a newsgroup devoted to it.
Over 250,000 new messages are posted to
newsgroups each day, containing Gigabytes of
information.
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11. What is the USENET? (cont)
Usenet is
– A content transport system like electronic mail
– A logical broadcast, one-to-many medium
network layered on top of other networks
Usenet resembles Bulletin Board System (BBS)
in most respects, & is the precursor to the various
Internet forums that are widely used today
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12. What is the USENET? (cont)
Derived from very early Unix networking
technology
– “Unix to Unix Copy (UUCP)”
Internet USENET hosts normally runs its own
protocol (NNTP) over TCP/IP, but can also use
UUCP over TCP
– UUCP over TCP useful in very bad network
conditions
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13. What is UUCP?
UUCP -- Unix to Unix Copy
– Actually a suite of programs to facilitate
transfer of files from one machine to another
machine over a network
UUCP Addressing is position-relative i.e. address
varies depending on where you are in the network
– Uses a path concept to trace route from
originating machine to destination
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14. History of USENET
First started at Duke University in USA in late
1970’s
First software was called “A News Software”
– “B News” and then “C News” (Still exists)
Originally, USENET consisted of two sets of
bulletin boards, mod.* (moderated) and net.*
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15. History of USENET
In mid-1980’s Network News Transport Protocol
(NNTP) was developed
– An application layer protocol using TCP
– Internet Network News (INN) and other TCP/IP
based news servers followed
In 1986, the Great USENET Renaming occurred
– Splitting mod.* and net.* into “the big 8” i.e. comp,
humanities, misc, news, rec, sci, soc, & talk
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16. How is it used?
Using newsgroups is very similar to using email.
Basically, you send a message, like an email
message, to a computer that stores your message
and makes it available for many other people to
read.
Similarly, you may access and read all of the
messages other people have posted. Usenet began
in the early 1980's as an electronic bulletin board
system, but is now much vaster.
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17. How is it used? (cont)
Most people who use the newsgroups use a
type of program called a newsreader, which
is a lot like your standard email client.
To use a newsreader you will have to have
the Internet address of a newsserver. There
are some free newsservers, but they are
limited.
Ex: www.dejanews.com
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18. Hierarchy of Newsgroups
Newsgroups are hierarchical
– comp. -- articles related to computers
– comp.protocols -- articles related to computer
(networking) protocols
– comp.protocols.tcp-ip -- articles related to
TCP/IP networking
– comp.protocols.tcp-ip.dns -- articles related
to the DNS (which uses TCP/IP and allows computers
to talk to each other)
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19. Who controls USENET?
No one organization controls Usenet.
Discussion group messages are stored on many
newservers around the globe.
New newsgroups can be created by anyone
– simply post a specially formatted article called
a “control message”
Most providers store the images for a period
varying from 2 to 30 days.
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20. The CSNET
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21. Introduction
Computer Science Network, CSNET is a
computer network that was developed by the U.S.
National Science Foundation in the early 1980's.
This allowed computer science and engineering
departments that were not doing research with the
DoD (Department of Defense) that could not
connect to ARPANET to connect to a network of
their own.
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22. Introduction
It linked Computer Science departments at
academic institutions together
It was funded by the U.S. National Science
Foundation by an initial contract for the three year
period 1981-1984.
It is a major milestone on the path to development
of the Internet
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23. History
Larry Landweber at the University of Wisconsin-
Madison made the original CSNET proposal,
originally reviewed by David Crocker, who also
contributed to email.
By 1981, three sites were connected - University
of Delaware, Princeton University, and Purdue
University.
By 1982, 24 sites were connected. By 1984, 84
sites were connected, including one in Israel
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24. History
It was intended as an extension to ARPANET, to
which many Computer Science departments didn't
have the privilege of access.
CSNET connected with ARPANET using TCP/IP,
and ran TCP/IP over X.25, but it also supported
departments without sophisticated network
connections, using automated dial-up mail
exchange.
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25. Components
CSNET has 3 main components:-
Phonenet mail system (Designed & developed at
University of Delaware)
Name server (Designed & developed at
University of Wisconsin-Madison)
A TCP/IP-over-X.25 tunnel (Designed &
developed at Purdue University)
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26. Components
Phonenet mail system (Delaware) –
Phonenet allowed an institution to have
Unix mail services with the underlying
transport mechanism being a loosely-
connected phone relay network.
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27. Components
Name server (Wisconsin) -
The name server allowed manual and
automated email address lookup based on a
variety of attributes of a user (e.g., name,
title, institution, etc.).
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28. Components
A TCP/IP-over-X.25 tunnel (Purdue) –
The X.25 tunneling allowed an institution to
connect directly to the ARPANET via a
commercial X.25 service (e.g., Telenet), where the
institution's TCP/IP traffic would be tunneled
through to a CSNET machine that would act as a
relay between the ARPANET and the commercial
X.25 networks.
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29. CSNET Evolution
CSNET was primarily made using Unix, but later it
was used on variety of hardware & O.S. platforms
CSNET was forerunner of NSFNet, the National
Science Foundation Network that eventually
became the internet
CSNET operated autonomously until 1989, when it
merged with Bitnet to form CREN
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30. The BITNET
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31. Introduction
BITNET is a major wide-area network
BITNET is a network of academic sites
comparable to but separate from the Internet.
It is not based on the TCP/IP protocols that
Internet networks must use. Therefore BITNET
isn't truly a part of the Internet.
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32. Introduction
BIT stands for “Because Its Time”, but original
meaning was "Because It's There Network".
Users can send and receive electronic mail to and
from the Internet, thanks to gateways that act as
"translators" between the different network
protocols.
Electronic mail is the only tool available--or
necessary--for BITNET sites.
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33. History
BITNET was a cooperative U.S. university
network founded in 1981 by Ira Fuchs at the City
University of New York (CUNY) and Greydon
Freeman at Yale University. The first network link
was between CUNY and Yale.
BITNET originated the utility known as the list
server and Internet users can get access to
BITNET list servers (or subscription lists).
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34. How to join BITNET?
The requirements for a college or university to join
BITNET were simple:-
Lease a data circuit (phone line) from a site to an
existing BITNET node.
Buy modems for each end of the data circuit,
sending one to the connecting point site.
Allow other institutions to connect to a site
without chargeback.
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35. Working of BITNET
BITNET differed from the Internet in that it was a
point-to-point "store and forward" network.
Bitnet's NJE (Network Job Entry) network
protocols, called RSCS, were used for the huge
IBM internal network known as VNET.
BITNET links originally ran at 9600 baud.
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36. Features of BITNET
The BITNET protocols were eventually
ported to non-IBM mainframe operating
systems
BITNET featured e-mail and the
LISTSERV software, but predated the
World Wide Web, the common use of FTP,
and Gopher.
It also supported interactive transmission of
files and messages to other users.
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37. Features of BITNET
The Interchat Relay Network, popularly known as
Bitnet Relay, was the network's instant messaging
feature.
BITNET's first electronic magazine, VM/COM,
began as a University of Maine newsletter and
surfaced broadly in early 1984
A text-based BITNET game called MAD became
the first global Multi-User Dungeon (MUD)
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38. Evolution of BITNET
At its zenith around 1991, BITNET extended to
almost 500 organizations and 3,000 nodes, all
educational institutions.
It spanned North America (in Canada it was
known as NetNorth), Europe (as EARN), India
(TIFR) and some Persian Gulf states (as GulfNet).
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39. Evolution of BITNET
BITNET was also very popular in South America,
where about 200 nodes were implemented and
heavily used in the late 1980s and early 1990s.
With the rapid growth of TCP/IP systems and the
Internet in the early 1990s, and the rapid
abandonment of the base platform (IBM
mainframe) for academic purposes, BITNET's
popularity and use diminished quickly.
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40. Evolution of BITNET
In 1996, CREN ended their support for BITNET.
The individual nodes were free to keep their phone
lines up but couldn’t stand for long.
As of 2007, BITNET has essentially ceased
operation.
However, a successor, BITNET-II, which
transmits information via the Internet still has
some users.
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41. S N A
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42. Introduction
IBM discovered that large customers were
reluctant to trust unreliable communications
networks to properly automate important
transactions.
In response, IBM developed Systems
Network Architecture (SNA)
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43. Introduction
SNA tries to identify literally everything that
could possibly go wrong in order to specify the
proper response.
Ex 1: Expected errors (such as a phone line or
modem failure)
Ex 2: Other errors (software problems,
configuration tables, etc.) are isolated, logged, and
reported to the central technical staff for analysis
and response.
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44. What is SNA
SNA stands for Systems Network
Architecture.
It was a mainframe network standard
introduced by IBM in 1974. SNA has
mainly been replaced by TCP/IP as more
people began to use the IP protocol
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45. What is SNA
This SNA design worked well as long as
communications equipment was formally
installed by a professional staff.
It became less useful in environments when
any PC simply plugs in and joins the LAN
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46. Forms of SNA
Two forms of SNA developed: -
Subareas (SNA Classic) managed by
mainframes
APPN (New SNA) based on networks of
minicomputers.
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47. Principal components and technologies
IBM Network Control Program (NCP) - packet
forwarding protocol
Synchronous Data Link Control (SDLC) - a
protocol which greatly improved the efficiency of
data transfer over a single link
Remote terminals i.e. those connected to the
mainframe by telephone lines
VTAM, a software package to provide log-in,
session keeping and routing services within the
mainframe.
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48. Working of SNA
In the original design of SNA, a network is built
out of expensive, dedicated switching
minicomputers managed by a central mainframe.
The dedicated minicomputers run NCP. No user
programs run on these machines. Each NCP
manages communications on behalf of all the
terminals, workstations, and PCs connected to it.
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49. Working of SNA
The mainframe runs an IBM product called
VTAM, which controls the network.
Although individual messages will flow from one
NCP to another over a phone line, VTAM
maintains a table of all the machines and phone
links in the network.
It selects the routes and the alternate paths that
messages can take between different NCP nodes.
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50. Working of SNA
A subarea is the collection of terminals,
workstations, and phone lines managed by an
NCP.
Generally, the NCP is responsible for managing
ordinary traffic flow within the subarea, and
VTAM manages the connections and links
between subareas.
Any subarea network must have a mainframe.
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51. APPN
The rapid growth in minicomputers,
workstations, and personal computers
forced IBM to develop a second kind of
SNA.
The new SNA is called APPN (Advanced
Peer to Peer Networking). APPN and
subarea SNA have entirely different
strategies for routing and network
management.
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52. Advantages
Localization of problems in the
telecommunications network was easier
Routing capability was with computer
rather than routers
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53. Disadvantages
Connection to non-SNA networks was difficult
A sheet of alternate pathways between every pair
of nodes in a network had to be predesigned and
stored centrally.
SNA network installation and maintenance are
complicated and SNA network products are (or
were) expensive.
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54. T H A N K S
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