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DEFENSE
DATA COMMUNICATIONS
1982-03-31
CHRISTIAN
ROVSING
A/S
Page
#
II F̲U̲N̲C̲T̲I̲O̲N̲A̲L̲ ̲E̲L̲E̲M̲E̲N̲T̲S̲ ̲O̲F̲ ̲I̲N̲T̲E̲G̲R̲A̲T̲E̲D̲ ̲
C̲O̲M̲M̲U̲N̲I̲C̲A̲T̲I̲O̲N̲ ̲S̲Y̲S̲T̲E̲M̲S̲
̲…86…1 …02… …02… …02… …02…
F̲U̲N̲C̲T̲I̲O̲N̲A̲L̲ ̲E̲L̲E̲M̲E̲N̲T̲S̲ ̲O̲F̲ ̲I̲N̲T̲E̲G̲R̲A̲T̲E̲D̲ ̲C̲O̲M̲M̲U̲N̲I̲C̲A̲T̲I̲O̲N̲ ̲S̲Y̲S̲T̲E̲M̲S̲
1. P̲R̲O̲D̲U̲C̲T̲S̲ ̲O̲V̲E̲R̲V̲I̲E̲W̲
Integrated communication encomposes the following products:
- Strategic and Tactical Transport Network consisting
of a series of Nodal switching centers interlinked
with tele lines.
- Message Processing and Electronic Mail Systems.
- Local Areas Networks
- View Data Systems
- Secure Gate Ways
Figure one presents a schematic overview of these products
and provides a reference to actual case story implementations.
Her kommer en teging
2. N̲E̲T̲W̲O̲R̲K̲S̲ ̲-̲ ̲S̲T̲R̲A̲T̲E̲G̲I̲C̲ ̲A̲N̲D̲ ̲T̲A̲C̲T̲I̲C̲A̲L̲
2.1 F̲e̲a̲t̲u̲r̲s̲
The communication systems which provide connections
between organizations situated in different countries,
as parts hereoff establish a backbone system for these
users. Such strategic networks and their interoperability
are of vital importance for the flow of information
between national and international organizations.
Up till now, different strategic network types have
been used for different purposes. Written telex messages
have been sent by one type of network, and telephone
calls have been provided using other types of system.
The integration of these different system is a mayor
concern for future strategic networks, and now modern
technology can provide a general and common strategic
network, which can serve as transmission media for
many different electronic mail application. For example
NATO has planned to implement a socalled NICS, NATO
Integrated Communication System in two phases. The
second phase will achieve the total integrated and
common system, but it is first planned to be implemented
in the 1990'es, although the technique is already available
now.
The features is strategic networks should include.
- Transmission of all types of information, text,
data and voice.
- High flexibility to provide supvivability and commonality
- Interoperability with other existing or planned
networks.
2.2 S̲y̲s̲t̲e̲m̲ ̲D̲e̲s̲c̲r̲i̲p̲t̲i̲o̲n̲
In the following a brief description of different network
types is provided and also the universal network concept
supported by international organizations and offered
by Christian Rovsing is described.
Message switching systems, have been used and are still
used to transmit messages in either manual or automatic
systems. In manual systems messages are punched on
paper tape and read into the transmission system, one
by one, to be transmitted from one switching center
to the next. At a switching center, a message is punched
out and interpretted by an operator to decide, which
outgoing transmission line should be used for the subsequent
transmission.
All this manual work can be automated, so that a switching
computer performs all tasks. A message switching system
of this type is called a store and forward system,
because a complete message is received and stored for
subsequent transmission. Transmission ???, but
if the priorities are essential, restriction or total
message length are essential.
Circuit switching system have been and are still used
for telephone or voice transmission. Before actual
transmission can take place the sending and receiving
part have to be connected by establishing a complete
circuit connection through different switching centers
to provide a physical connection between the two parties.
This type of network is the most suitable for lengthy
exchange of information between two parties, as is
the case with telephone conversation. For short time
transmission of telex messages, this connection scheme
is run economical. because it will take too long time
to establish the connection and it is to expensive
to keep connection permanently if they are seldomly
used. Circuit switching applies either analog or digital
coding scheme for transmission.
Packet switching schemes have been introduced in networks
to simplify switching centers. The concept of storing
and forwarding total messages has been changed to partion
messages in standard size packages and not to store
these packages for longer time at each switching center.
Instead, packets are immediately transmitted to the
next switching node. This approach has overcome some
of the problems, inte? in message switching, e.g. no
limitation on message service. However the recipient
now has to assemble the packets to reestabllish the
total message. The first packet switching networks
were of the socalled datagram …86…1 …02… …02… …02… …02…
types, where individual packets contained enough information
to be routed independently through a network, but the
consequence of this might be that packets belonging
to the same message might arrive at the destination
using different routes through the network and what
was worse, might not arrive in the same sequence they
were transmitted.
Although the packets switching network was an improvement
compared to message switching, they do not provide
interoperability with circuit switching network. Voice,
which has been digitized can be transmitted as individual
packets, but they must arrive in the same sequence
they were sent to give meaning to the user.
It has been a mayor concern for international organization
to work for standardization `of network types, and
standards are now available which provides these.
CCITT has provided two essential standards in this
concept. The X25 which describes have user system
shall interface to network using a socalled virtual
circuit concept. In order to interconnect different
network, e.g. public networks in different countries.
CCITT provides the X75 standard which describes the
rules for gateways between different networks.
These standards can also be used when interfacing
to tactical networks to provide interoperability between
tactical and strategic network. This concept is essential,
because tactical network might use different schemes.
For example, without NATO's European countries, the
socalled EUROGROUP has established standards, i.e.
EUROCOM to be followed for future tactical networks.
Packet switching network using the virtual circuit
concept can provide a general transmission scheme for
all types of digitized data, e.g. messages, telephone,
computer data, equipment control or monitoring data.
The idea behind virtual circuits, is, as the name impolies,
non physical circuit can be established in a network
through several switching centers. Each physical connection,
wire or radio, contains numerous logical. By applying
time or frequency multiplexing …86…1 …02… …02… …02… …02…
between the logical lines, pseudo circuits can be established
to be used for continuous information eaxchange like
telephone conversation. For transmission of written
messages, text or datal, statistical multiplexing can
be applied to only utilized the physical circuits for
the individual virtual circuits when required.
The two types of multiplexing scheme can be combined
by using the statistical multiplexing scheme in some
of the time or frequency slots available.
The packet switching protocol of the virtual circuit
type provides a general transmission scheme which ensure
interoperability between national strategic network
and provides a well-defined interface between strategic
and tactical networks.
FEurthermore, this scheme is in accordance with the
structured approach for constructing software in total
integrated communication syhstems, the socalled OSI
7 layer model recommended by ISO, the international
organization for standardisation. OSI means Open System
Interconnections.
Her kommer en tegning.
3. M̲E̲S̲S̲A̲G̲E̲ ̲P̲R̲O̲C̲E̲S̲S̲I̲N̲G̲ ̲A̲N̲D̲ ̲E̲L̲E̲C̲T̲R̲O̲N̲I̲C̲ ̲M̲A̲I̲L̲
3.1 F̲e̲a̲t̲u̲r̲e̲s̲
Advantages in computer technology has provided many
different services to the modern information based
society. Within the military community it is realized,
how vital availability of extensive and up to date
information is for the decision making process behind
any military operation.
Success in warfare has always been based on information
reporting that is why many resources have been spent
on observations and reporting of all type of informations.
This process has been slow, full of mistakes and manpower
consuming
The automation of some of these functions pertaining
to message processing and the possibility of automating
even more functions will yield great benefits when
implemented.
The concept of message processing and electronic mail
is based on the fact that many activities herein are
recurring and subject to automation. These activities
include:
- Drafting of message with extensive correction and
restructuring
- Guidance in information entry
- Validation of message syntax, i.e. total structure,
substructure, length of lines, length of fields,
type of fields.
- Coordination of message contents and subsequent
correction before approval.
- Schedule monitoring in reporting
- Distribution of messages within an organization
- Filing and retrieval of information
- Remote connection between users and/or system
3.2 S̲Y̲S̲T̲E̲M̲ ̲D̲E̲S̲C̲R̲I̲P̲T̲I̲O̲N̲
The introduction of modern visual display units, VDUs
to replacement of old typewriters or telexmachine gives
immence improvement of the working situation for the
mesage preparation personel.
A VDU provides within itself many functions which will
assist the person in preparing messages. It will display
a format or layout of the message to be prepared, which
contains much more guidance information earlier offered
on paper formats.
The layout is stored within the system and can be retrieved
immediately by the user, without leaving his workstation.
The system can store much more different layouts or
format than is pratical in a manual environment.
The entered information will be checked for syntactic
errors instantaneously and it will be checked for semantic
errors before accepted by the system. This ensures
that no extra human intervention will be required in
the message processing.
The types of syntactic checks comprise the quantity
of subset information or fields within the message.
No mandatry information will be forgotten. The system
will ensure that information which should be numerical
will be entered as such, etc.
The semantic checks which can be performed are extensive.
Information which much belong to a known large set
of information set can be checked. For example the
recipient of a message can be validated before final
acceptance of a message.
As soon as a messsage has been accepted by the system
from the drafters work station, it can be processed
automatically without any delay. It is already typed,
so no further entry by typist is required, and by electronic
mail facilities it can be conveyed to the recipient
instantaneously.
Reception of message is the other aspect of message
processing, whether the recipient is a human being
or a computer system. In the traditional sense, where
people …86…1 …02… …02… …02… …02…
receives messages from other people, computer systems
can now automate many of those time - and manpower
consuming activities known from manual systems.
The electronic mail capabilities can now reach the
individual recipients workstation without any time
delay and without manual delivery of messages from
the communication center to the recipient.
In many military organizations complex delivery rules
are applied in order to derive final receivers, either
action or information receives, as a result of the
subject of the messages. These rules can be programmed
into the message processing system to avoid mistakes
and time delays.
Modern message processing system will also assist users
in filing and retrieval of their messages. Many different
subject keywords can be used simultaneously without
duplication of physical files.
When messages are part of a greater information collection
scheme, modern computer systems can perform all the
processing pertained to message reception functions.
It can enforce timely reporting, where required, and
it can accumulate information received in several message
to provide the decision maker with an overview. These
summaries might be provided on graphic terminals instead
of alphanumeric displays.
The overall organization of the human activities is
an essential part of computer assisted message processing.
Within a military organization the abuility to distinguish
between the urgency of any subject is vital. When precedence
or urgency indicators are first introduced in messages,
the computer system can enforce the correct time sequencing
of all subsequent handling of these messages. For
example during preparation of a message, the user at
the workstation will immediately be informed if any
urgent message arrives at his terminal. Likewise modern
workstations can be connected to more than one system
and assist the user in the overall prioritoring of
this work.
One of the aspects of message processing as described
above is the gradual transition into a paperless society.
In the military organization, this has many …86…1
…02… …02… …02… …02…
security aspects. First the computer system checks
who have access to any informatin, at it logs all events
for later investigation if required. Secondly it minimizes
the need for paper copies and hence it minimizes the
risk of security leaks.
The aspects of electronic mail capabilities within
the military community are even more astonishing than
message processing capabilities themselves.
The electronic mail capabilities of modern communication
systems are used to convey messages from one place
to one or several other places without delays caused
by human intervention. This capability is now so fast
that conferencing systems can be set up, allowing for
immediate response to any message. Pseudo meeting can
now be held with participating members situated at
geographical distance locations. Sitting at their respective
workstations they can prepare information, which immediately
will be displayed at all the other members' workstations.
Answers can be entered by the other members and the
dialog between two or more members can continue as
long as required.
To realy understand the implication of electronic mail
capabilities, it might be illustrative to imagine that
anything which can be coded in numbers can be transmitted
from one place to another. Examples are pictures like
radar display data, maps, drawings, fingerprints or
voice in digitized formats. All these different types
of information can now be transported over the same
transmission media, given great flexibility and survivability
characteristics, which are vital in a military environment.
The electronic mail capability can also provide the
user at his workstation remote access to computer systems.
In the military environment, the aspect of remote access
can provide the user in battle at the frontier access
to a computer placed for behind the battlefields.
More specialized or dedicated computers can also be
accessed from remote. Systems which contains spare
parts inventories can be accessed without human interaction.
Handbooks of any kind, dictionaries or even computers
capable of human language translation could be provided
as service to users, and only one universal workstation
is required.
So called expert systems, which applies artificial
intelligence can be of great importance in the military
environment. The necessity of the presence of many
experts can now be minimized. An example known from
the commercial industry is, medical diagnostification
performed by a non medical expert.
Maintenance and repair of all kinds of equipment, including
computer equipment, can benefit from electronic mail
connections to expert systems.
The implications of introduction of computer message
processing and electronic mail functions are for reaching
and can not easily be overestimated.
4. LOCAL AREA NETWORKS
4.1 FEATURES
Local area network provides a common and economical
media for interconnecting different terminal types
to one or more systems. Essential features are:
- Avoiving nummerous point to point connection wires
between one computer and several terminals.
- Provide felxibility in terminal placement within
a building and give easy relucation capabilities.
- Provide access to several dedicated computers within
the same or different local area networks by using
the same terminal.
4.2 SYSTEM DESCRIPTION
Instead of establishing multiple connections between
a computer and its terminals, which is very costly,
modern technology provides the capability to equip
all rooms in a building or a local area, like a ship
with a common transmission media outlet. A single coaxial
cable, known from television antenn-connections can
be …86…1 …02… …02… …02… …02…
installed in a building, going from toom to toom in
the same fashion which power outlets are provided in
all rooms. This can be done at building errection time
or later as a one time investment.
Ones installed a local area network provides great
flexibility in actual placement of terminals. The terminals
can be moved from room to room and connected to the
network via the outlet placed in each room. No relation
cost are involved.
The local area network allows connections of several
different makes of terminal equipment. A small m,icroprocessor
based terminal adaptor can interface any old type of
terminal to the modern communication scheme used in
modern terminals and in the network itself.
All terminals and computers attached to the same network
can exchange information, i.e. a local area network
can provide an electronic mail facility within a building
or small society.
Any computer attached to the network can now be reached
by any terminal. For example, a person who works partly
with a text processing system, and partly prepare and
sends telexes, and partly does data entry for an accounting
system, can use the same terminal for all three application
even if they are placed on three different computers,
as long as the computers are attached to the local
area network.
If one of the computers attached to the network acts
as a gateway to long hand networks, then any terminal
user has access to all the services that can be provided
through the long hand network.
The types of terminals that can be hooked up on a local
area network are not only human work stations, by any
type of automatical sensing device might report its
data through a local area network. Examples are fire
alarms. burgler alarms equipment checkout devices and
they can be installed in local areas, buildings aeroplans,
ships etc.
The ease of installation has been achieved by only
applying a single common transmission line throughout
the area. For relyability reason this transmission
media might be dualized to provide back up solutions.
Secure communication is vital in military organizations.
To provide this modern fiber optics can be utilized.
This provide a communication line, which can not be
tapped without easily spotted physical changes to the
line. On the other hand a fiber optic connection line
can not be jamned from outside. The aspect of this
on board a ship might be essential.
The concept of local area network is essential in achieving
interoperability throughout the information processing
sphere. It provides the common and overall interface
from the end user, human or not, to all type of destinations,
system or human, in an economical fashion.
Figure
5. S̲E̲C̲U̲R̲E̲ ̲G̲A̲T̲E̲W̲A̲Y̲S̲
5.1 F̲E̲A̲T̲U̲R̲E̲S̲ ̲
A Secure Gateway is typically placed between two information
processing systems to allow for a controlled, and secure
exchange of data. The features of a Secure Gateway
may include:
- Conversion of possible differences in the communication
protocols and data formats between the two interlinked
systems.
- Screening and vetting of the transfered information
- Validation of security procedures.
- Physical isolation between the two systems.
- Buffering of data during temporary close down of
the connection to either of the systems.
5.2 S̲Y̲S̲T̲E̲M̲ ̲D̲E̲S̲C̲R̲I̲P̲T̲I̲O̲N̲
A Secure Gateway may be implemented in two different
ways:
1. The gateway act as a transparent system that passes
on the data immediately upon arrival and without
storing the data internally in the gateway. This
type of gateway serves typically as a converter
between two systesm using different communications
protocols.
2. The other type of gateway act as a screeing station
that validates all traffic between two systems
and act the sometime perform necessary protocol
and format conversion. The validation may be performed
either automatically by comparison with prestored
approved formats, or manually using a man-in-the-loop
type procedure.
The first type of gateway typically need not take responsibility
for continuity of the data traffic as this task will
be handled by the two interconnected system.
The second type of gateway will typically need to store
the information in the gateway for such a long period
that the converter need to take responsibility for
the information during the transfer and perform normal
acknowledgements to the two interlinked systems.
The structure of a typical gateway to be used for transfer
of message traffic is shown in figure 1. The softare
is structured in accordance with the protocol levels
and consist of
Level 1: Handling of the data link control signals;
typically V24/X21.
Level 2: Link access protocol to ensure an errorfree
transfer of data frames from system to
gateway; typically X25 LAP B or HDLC.
Level 3: Frame or packet assembly/disassembly. This
level ensures the correct assembly/disassembly
of messages into packets or frames. In
a system with different levels of precedence
for the message traffic, level 3 may also
facilitate multiplexing of data frames
from different messages accross the link.
This means that a low priority message
that is in process of being transferred
may be interrupted by a higher priority
message. After transfer of that message
the transfer of the lower priority message
is resumed from where it was interrupted.
Level 4: Traffic Handling. This level controls that
messages are transferred in accordance
with precedence and security rules. It
further ensures that no messages are lost
on the communication line and have built-in
procedures to handle recovery from transmission
errors.
Figure 5.1 GATEWAY
Functional layout
Level 5: This level provides al required format
conversion due to differences in header
information, address information or presentation
formats. It, further, emulates differences
in service and control messages accross
the interface.
In case that screening of the message is required level
5 ran/d also include a message analysis facility and/or
an interface to a visual display unit (VDU).
The Gateway would typically be based on a microcomputer
or a small inicomputer possibly with a small disc for
storage of the message. The programs may either be
stored on the disc or in a Read Only Memory.
6. V̲I̲E̲W̲D̲A̲T̲A̲ ̲
Viewdata is a facility for retrieving information from
computer data bases. The information is stored in "pages"
in the VIDEOTEX system or may optionally be retrieved
from external bases.
Viewdata adds, to a data processing environment, the
capability of using low-cost and standardized terminals
to interact with different data bases in a user-oriented
way. It can be implemented as part of an Electronic
Mail Service.
Viewdata offers the following capabilities:
- Retrieval of Viewdata images from a database
- Generation/modification of Viewdata images
- Maintenance of user catalogue
- Provision for generation of users in user groups
- Maintenance of password
- Message service
- Generation of primary keywords
A viewdata database supports three user access methods:
- hierarchical search
- direct page selection
- selection by keyword
Thus, Viewdata can provide user-friendly data presentation
display in connection with a database.
