network
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... sockets having unique identifiers. We propose the implementation of
a slightly modified subset of the network commands specified in
NWG/RFC36 plus the ERR ...
... Given the basic objective of getting all ARPA contractors onto the
network and talking to each other at the earliest possible date, we
think that it is important to implement an initial protocol that is
reasonably simple yet extendable while providing for the major
...
... think that it is important to implement an initial protocol that is
reasonably simple yet extendable while providing for the major
initial uses of the network. It should be a simple protocol so as to
elicit the broadest possible support and to be easily implementable
at all installations with a minimum of added software.
...
... 4. Sockets are conceptualized as having several states, and these are
related to conditions under which network requests may be queued.
This differs from the unlimited queuing feature, which presents
certain implementation difficulties.
...
...
It seems convenient and useful to view the network as consisting of a
hierarchy of protocol and implementation levels. In addition to
aiding independent software and hardware ...
... experimental or special purpose systems.
We view the initial network communications system as a hierarchy of
three systems of increasing generality and decreasing privilege
level. These are:
...
... 1. IMP Network - The network of IMPs and physical communication lines
is the basic resource which higher level systems convert into more
...
... is the basic resource which higher level systems convert into more
generalized communication facilities. The IMP network acts as a
"wholesaler" of message transmission facilities to a highly
privileged module within each HOST ...
... Network Control Program - Each HOST contains a module called the
Network Control Program (NCP) which has sole control over
communications between its HOST ...
... communications between its HOST and the IMP network. It acts as a
"retailer" of the wholesale communications facilities provided by
the IMP ...
... "retailer" of the wholesale communications facilities provided by
the IMP network. The network of NCPs can be viewed as a higher
...
... the IMP network. The network of NCPs can be viewed as a higher
level communications system surrounding the IMP ...
... NCPs can be viewed as a higher
level communications system surrounding the IMP network which
factors raw message transmission capabilities between HOSTs into
...
... - - - - - - |- - - |- - - |- - -|- - -|- - |- - -|- - - |- - - - - -
| | | | | NCP NETWORK | | | |
| | | | | | | | | | |
| _|_____|______|______|_ | | _|_____|______|_ |
...
... - - - - - - - - - - - -|| - - - - - - - - - - ||- - - - - - - - - -
|| IMP NETWORK ||
___||___ ____||__
| | | |
...
... |________|
FIG 1. Modular View Of Network
3. User Control and Communication Module - The preceding two
...
... communication systems are sufficient to permit communication
between unprivileged processes that already exist. However, one
of the primary initial uses of the network is thought to involve
the creation of a foreign user process through interaction with
the foreign HOST ...
... process. Except for the ability to close connections to a dead
process, the UCC module has no special network privileges. The
UCC protocol is only one of several third-level protocols that
...
... III - NETWORK CONTROL PROGRAM ...
...
Each HOST implements a module called the Network Control Program
(NCP) which controls all network ...
... Network Control Program
(NCP) which controls all network communications involving that HOST.
The network ...
... network communications involving that HOST.
The network of NCPs forms a distributed communication system that
implements communication paths between individual processes. The NCP ...
... socket identifier is used throughout the
network to uniquely identify a socket. It consists of 48 bits,
...
... socket belongs. A user's first process at a HOST to use the
network receives instance tag = 0 by convention.
...
...
The NCP network coordinates its activities through control commands
passed between its individual components. These commands generally
concern the creation and manipulation of socket ...
... link), which is
reserved for that purpose. The IMP network does not distinguish
between these messages and regular data messages implementing
...
...
An NCP issues this network command to disconnect an existing
connection or to negatively acknowledge an RFC. There is a
...
... socket. Data already in transit within
the NCP network over the interrupted connection will be
transmitted to the destination ...
... ERR <code> <command length> <command in error>
This command is used to report spurious network commands or
messages, or overload conditions that prevent processing of the
...
... command. <code> specifies the error type. If <code> specifies an
erroneous network command, <command in error> is that command (not
including IMP header ...
... switch> 'off'. We feel that this
command will be of considerable aid in the initial shakedown of
the entire network.
h. No Operation Command
...
... HOST has an interface through which a local process
can exercise the network, subject to the control of the NCP. The
...
... NCP. The
exact specification of this interface is not a network protocol
issue, since each installation will have its own interface keyed to
...
... requirements for the user
interface to an NCP are that it provide all intended network
functions and no illegal privileges. Examples of such illegal
...
... eavesdrop on communications not intended for it, or to induce the NCP
to send out spurious network commands or messages.
We outline here an interface ...
... We outline here an interface based on the Carr, Crocker, and Cerf
proposal that is sufficient to fully utilize the network. While this
particular set of calls is intended mainly for illustrative purposes,
it indicates the types of functions necessary.
...
... 'Aa12' is discarded. To allow remaining messages already in
transit from process 'b' to percolate through the IMP network to
NCP A and be discarded without error comments, NCP ...
...
Some process must exist which agrees to listen to anybody in the
network and create a process for him upon proper identification.
This process is called the logger and interacts through the NCP ...
... This process is called the logger and interacts through the NCP via
the network-related User Control and Communication (UCC) module,
which implements the necessary protocol. Except for one instance
(CLOSEing connections ...
... (CLOSEing connections of dead processes), the process operating the
UCC module does not have special network privileges.
...