network
Click on the red underlined text to get to the source
...
The Advanced Research Projects Agency (ARPA) Computer Network
(hereafter referred to as the "ARPA network") is one of the most
...
... ARPA) Computer Network
(hereafter referred to as the "ARPA network") is one of the most
ambitious computer networks attempted to date. [1 ...
... (hereafter referred to as the "ARPA network") is one of the most
ambitious computer networks attempted to date. [1] The types of
machines and operating systems ...
... 1] The types of
machines and operating systems involved in the network vary widely.
For example, the computers at the first four sites are an XDS 940
(Stanford Research Institute), an IBM 360/75 (University of
...
... Los Angeles), and a DEC PDP-10 (University of Utah). The only
commonality among the network membership is the use of highly
interactive time-sharing systems; but, of course, these are all
different in external appearance and implementation. Furthermore, no
...
... different in external appearance and implementation. Furthermore, no
one node is in control of the network. This has insured reliability
but complicates the software.
...
... but complicates the software.
Of the networks which have reached the operational phase and been
reported in the literature, none have involved the variety of
computers and operating systems ...
... reported in the literature, none have involved the variety of
computers and operating systems found in the ARPA network. For
example, the Carnegie-Mellon, Princeton, IBM network consists of
...
... operating systems found in the ARPA network. For
example, the Carnegie-Mellon, Princeton, IBM network consists of
360/67's with identical software. [2] Load sharing among identical
...
... in the early 1960's. Therefore, the implementers of the present
network have been only slightly influenced by earlier network
attempts.
...
... implementers of the present
network have been only slightly influenced by earlier network
attempts.
...
... MIT, Lincoln Laboratory, and System Development
Corporation (all ARPAA sponsored) have had considerable influence on
the design of the network. In some sense, the ARPA network of time-
shared computers is a natural extension of earlier time-sharing
...
... Corporation (all ARPAA sponsored) have had considerable influence on
the design of the network. In some sense, the ARPA network of time-
shared computers is a natural extension of earlier time-sharing
concepts.
...
... concepts.
The network is seen as a set of data entry and exit points into which
individual computers insert messages destined for another (or the
same) computer, and from which such messages emerge. The format of
...
... individual computers insert messages destined for another (or the
same) computer, and from which such messages emerge. The format of
such messages and the operation of the network was specified by the
network contractor (BB ...
... such messages and the operation of the network was specified by the
network contractor (BB&N) and it became the responsibility of
representatives of the various computer sites to impose such
...
... BB&N staff provided substantial assistance and guidance while
delivering the network.
We have found that, in the process of connecting machines and
...
... operating systems together, a great deal of rapport has been
established between personnel at the various network node sites. The
resulting mixture of ideas, discussions ...
... HOSTs at a particular
site, and allows HOSTs access into the network. The configuration
of the initial four-HOST network ...
... network. The configuration
of the initial four-HOST network is given in figure 1. The IMPs
from a store-and-forward communications network. A companion
...
... HOST network is given in figure 1. The IMPs
from a store-and-forward communications network. A companion
paper in these proceedings covers the IMPs in some detail. [3]
...
... sent. Each link is unidirectional and is controlled by the network
so that no more than one message at a time may be sent over it. This
control is implemented using RFNM ...
... links
in each direction and that no relationship among these is imposed by
the network.
The purpose of the link ...
... HOST protocol cooperates
with this assumption. An even more basic assumption, of course, is
that the network's load comes from some users transmitting sequences
of messages rather than many users transmitting ...
...
The computers participating in the network are alike in two important
respects: each supports research independent of the network, and each
...
... The computers participating in the network are alike in two important
respects: each supports research independent of the network, and each
is under the discipline of a time-sharing system. These facts
contributed to the following design philosophy.
...
... contributed to the following design philosophy.
First, because the computers in the network have independent purposes
it is necessary to preserve decentralized administrative control of
...
... accounting and resource allocation
mechanisms, we arranged matters so that these mechanisms would
control the load due to the network in the same way that they control
locally generated load.
...
... mechanisms.
Third, because this network is used by experienced programmers it was
imperative to provide the widest latitude in using the network.
...
... Third, because this network is used by experienced programmers it was
imperative to provide the widest latitude in using the network.
Restrictions concerning character sets, programming languages ...
... would not be tolerated and we avoided such restrictions.
Fourth, again because the network is used by experienced programmers,
it was felt necessary to leave the design open-ended. We expect that
...
... we felt constrained not to impose them arbitrarily.
Fifth, in order to make network participation comfortable, or in some
cases, feasible, the software interface to the network ...
... network participation comfortable, or in some
cases, feasible, the software interface to the network should require
minimal surgery on the HOST operating system ...
... operating system.
Finally, we except the assumption stated above that network use
consists of prolonged conversations instead of one-shot requests.
...
...
These considerations led to the notions of connections, a Network
Control Program, a control link, control commands, sockets ...
... HOST communicate with the network through a
Network Control Program (NCP). In most HOSTs, the NCP ...
... Each user is assigned a 24-bit user number which uniquely identifies
him throughout the network. Generally this will be the 8-bit HOST
...
... creates is tagged with his user
number. When the user signs onto a foreign HOST via the network, his
same user number is used to tag processes he creates ...
...
A vocabulary of control commands has been defined for communication
between Network Control Programs. Each control command consists of
an 8-bit operation code to indicate its function, followed by some
...
... HOSTs are provided. It is not mandatory
that the user use such subroutines, since the user has access to the
network system calls in his monitor.
In addition to user programming access, it is desirable to have a
...
... In addition to user programming access, it is desirable to have a
subsystem program at each HOST which makes the network immediately
accessible from a teletype-like device without special programming.
Subsystems are commonly used system components such as text editors,
...
... accessible from a teletype-like device without special programming.
Subsystems are commonly used system components such as text editors,
compilers and interpreters. An example of a network-related
subsystem is TELNET, which will allow users at the University of Utah
...
... terminal users. It is expected that more sophisticated subsystems
will be developed in time, but this basic one will render the early
network immediately useful.
A user at the University of Utah (UTAH) is sitting at a teletype
...
... The TELNET subsystem coding should be minimal for it is essentially a
shell program built over the network system calls. It effectively
established a shunt in the user HOST between the remote user and a
...
... HOST and a manual for the serving HOST, the network can be profitably
employed by remote users today.
...
...
The network poses special problems where a high degree of interaction
is required between the user and a particular subsystem in a foreign
HOST ...
... operating systems overhead, and network transmission delays. Unless
we use special strategies it may be difficult or even impossible for
a distant user to make use of the more sophisticated subsystems
...
... consoles connected by telephone, and then this subsystem becomes
available to network users. This subsystem might have the following
characteristics.
...
... those in another, but not vice versa. We can imagine that any scope
might be an adequate substitute for a teletype, but hardly the
reverse. This observation leads us to wonder if a network-wide
language for consoles might be possible. Such a language ...
... class. Each site could then write
interface programs for its consoles to make them look like network
standard devices.
...
... for the response. Some interactive subsystems are especially
pleasant to use because a great deal of work has gone into tailoring
the responses to the user's expectations. In the network, however, a
local user level process intervenes between a local console and a
foreign subsystem, and we may expect the response time for minor
...
... performance because of the delays it introduces.
These arguments have led us to consider the possibility of a Network
Interface Language (NIL) which would be a network-wide language ...
... These arguments have led us to consider the possibility of a Network
Interface Language (NIL) which would be a network-wide language for
writing the front end of interactive subsystems. This language ...
... writing the front end of interactive subsystems. This language would
have the feature that subprograms communicate through network-like
connections. The strategy is then to transport ...
... requirement here is that any device can be modeled by a NIL
program. For example, if a network standard display controller
manipulates tree-structures according to messages sent to it
...
... IMP. The messages have no particular order other than arrival
times at the IMP. The Network Control Program at one HOST (e.g.,
UTAH) needs waiting RFNM ...
...
At this time (February 1970) the initial network of four sites is
just beginning to be utilized. The communications system of four
IMPs and wide band telephone ...
... possible and is highly effective.
Work on the ARPA network has generated new areas of interest. NIL is
one example, and interprocess communication is another. Interprocess
communication over the network ...
... ARPA network has generated new areas of interest. NIL is
one example, and interprocess communication is another. Interprocess
communication over the network is a subcase of general interprocess
communication in a multiprogrammed environment. The mechanism of
connections ...
... L. ROBERTS "The ARPA network" Invitational Workshop on Networks of Computers Proceedings National Security Agency 1968 p 115 ff ...
... L. ROBERTS "The ARPA network" Invitational Workshop on Networks of Computers Proceedings National Security Agency 1968 p 115 ff ...
... R M RUTLEDGE et al "An interactive network of time-sharing computers" Proceedings of the 24th National Conference Association for Computing Machinery 1969 p 431 ff ...
... F E HEART R E KAHN S M ORNSTEIN W R CROWTHER D C WALDEN "The interface message processors for the ARPA network" These Proceedings ...
... UCLA
Figure 1 Initial network configuration
...