ARPANET(Advanced Research Project Agency Network)
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switching network with distributed control and one of the first networks to implement the TCP/IP protocol suite. Both technologies became the technical foundation of the Internet. The ARPANET was established by the (ARPA) of the United States Department of Defense.
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.
It was in response to USSR’s Sputnik
launch in 1957.
It connected 4 major universities:
–
1)University of California (@Los Angles)
2)University of California (@Berkeley)
3)University of Utah
4)Stanford Research Institute
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.
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.
The software was needed between IMPs to
provide communication.
Also, software was needed to provide hostIMP, 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.
