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DEFENSE DATA COMMUNICATIONS 1982-03-31
CHRISTIAN ROVSING A/S Page #
II F̲U̲N̲C̲T̲I̲O̲N̲A̲L̲ ̲E̲L̲E̲M̲E̲N̲T̲S̲ ̲O̲F̲ ̲I̲N̲T̲E̲G̲R̲A̲T̲E̲D̲
C̲O̲M̲M̲U̲N̲I̲C̲A̲T̲I̲O̲N̲ ̲S̲Y̲S̲T̲E̲M̲S̲
F̲U̲N̲C̲T̲I̲O̲N̲A̲L̲ ̲E̲L̲E̲M̲E̲N̲T̲S̲ ̲O̲F̲ ̲I̲N̲T̲E̲G̲R̲A̲T̲E̲D̲ ̲C̲O̲M̲M̲U̲N̲I̲C̲A̲T̲I̲O̲N̲ ̲S̲Y̲S̲T̲E̲M̲S̲
1. P̲R̲O̲D̲U̲C̲T̲S̲ ̲O̲V̲E̲R̲V̲I̲E̲W̲
The Systems Division of Christian Rovsing A/S have
relevant experience in virtually all phases of data
communication. Our involvement goes from individual
element design through interfacing to total system
responsibility. Figure 1 illustrates the involvement
of Christian Rovsing A/S in terms of product realization
- showing each product in relation to the layers of
our system architecture.
Of special interest with respect to defense data communication
systems are the following products:
o Strategic and Tactical Transport Networks - FIKS
and NICS-TARE
o Message Processing and Electronic Mail System -
CAMPS, FIKS
o Local Area Network - TDX
o Secure Gateway - CR Protocol Converter
o View Data - VIDEOTEX.
In the sections to follow, the five abovementioned
types of products are discussed. Further details of
product realization are given in section III, describing
objectives, benefits system functions, equipment, and
expandability of representative products
Figure 1
PRODUCT REALIZATION
structural relationship of elements
of data communication systems
2. N̲E̲T̲W̲O̲R̲K̲S̲ ̲-̲ ̲S̲T̲R̲A̲T̲E̲G̲I̲C̲ ̲A̲N̲D̲ ̲T̲A̲C̲T̲I̲C̲A̲L̲
F̲e̲a̲t̲u̲r̲e̲s̲
Modern strategic and tactical networks require the
following features:
o Transmission of all types of information, text,
data and voice.
o High flexibility to provide survivability and commonality.
o Interoperability with other existing or planned
networks.
o Security, privacy and availability of service
Until recently, transmission of different types of
information have been accomplished by various means;
e.g. written telex messages by one type of network
and telephone communication via a different network.
The integration of different networks is now obviously
a major goal. As an example, NATO plans to complete
implementation of NICS - N̲ATO Integrated C̲omuncation
S̲ystem - in the 1990's.
Christian Rovsing A/S believes that such networks and
their interoperability are of vital importance for
the flow of information between national and international
organizations, and we have devoted many resources to
provide solutions for communication network implementations
tailored to meet all the required features listed above.
Figure 2 illustrates interoperability of National and
Allied Networks - strategic and Tactical. Descriptions
of different network types with which Christian Rovsing
A/S has significant experience are given in the next
section.
Figure 2
NETWORK INTEROPERABILITY
connecting national and allied data communication systems
S̲y̲s̲t̲e̲m̲ ̲D̲e̲s̲c̲r̲i̲p̲t̲i̲o̲n̲
The following describes different network types and
universal network concepts required by defense organizations
and offered by the Systems Division of Christian Rovsing
A/S .
C̲i̲r̲c̲u̲i̲t̲ ̲S̲w̲i̲t̲c̲h̲i̲n̲g̲ Systems meet the need 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 duration transmission of telex
messages, this connection scheme is uneconomical because
it will take too long to establish the connection,
and it is too expensive to keep connections permanently
if they are seldom used. Circuit switching applies
either analog or digital coding schemes for transmission.
M̲e̲s̲s̲a̲g̲e̲ ̲S̲w̲i̲t̲c̲h̲i̲n̲g̲ Systems meet the need 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 each 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.
This labor can be automated, so that a switching computer
performs all tasks. This type of message switching
system is called a store and forward system because
a complete message is received and stored for subsequent
transmission. The computer switching system performs
error detection and correction (EDC) on all messages
transmitted. Christian Rovsing A/S's System Division
has implemented message switching and protocols in
projects like CAMPS, FIKS and the NICS-TARE Front-End.
P̲a̲c̲k̲e̲t̲ ̲s̲w̲i̲t̲c̲h̲i̲n̲g̲ ̲is part of the Christian Rovsing A/S
product line, with all elements to provide the backbone
data communication environment networks. This modern
data communication technology leads to simplified switching
centers and provides a very general and flexible communication
environment. Furthermore, this technique lends itself
to modern digital transmission technology.
Packet switching deviates from store-and-forward basicly
in two areas. First, messages are partioned in a sequence
of subunits called packets; these are transmitted individually
through the network. Second, packets are retransmitted
immediately at intermediate switching centers. This
leads not only to low transfer times through the network
compared to store-and-forward but also to nodes with
minimal requirements to memory, internal as well as
external.
The need for supporting interactive and bulk data in
an integrated network has resulted in two switching
techniques, virtual circuit and pure packet (datagram)
based techniques.
Datagram techniques require that all packets contain
self-sufficient routing information. This, of course,
leads to higher overheads. One concern is long messages
consisting of multiple packets; packets are routed
independently through the network possibly using different
routes; as a consequense, packets belonging to the
same message might arrive to the destination out of
sequence; thus, a resequencing may have to take place
at the destination. However, this technique is well
suited for bursty types of traffic, e.g. interactive
and query/response. Furthermore, this service is useful
to a growing class of subscribers who want to utilize
only the basic transmission service from a data communications
network. These subscribers either do not need an end-to-end
protocol or prefer to provide their own.
Virtual circuits established between users provide
an alternative technique well suited for bulk data
transfers, e.g. digitized voice. Packets of a message
are routed along a predetermined path - the virtual
circuit - through the network. Several users may simultaneously
use the same circuit for data transmission, hence the
term virtual. Thus, an attractive means for implementing
interoperability with voice switching may be offered
by this technique.
Another major aspect of communication is the concern
for international standardization of network types,
and standards are now available which provides these.
As an example CCITT has provided two essential standards
in this concept. The X.25 describes how user systems
shall interface to networks using a virtual circuit
concept in order to interconnect different network,
e.g. public networks in different countries. CCITT
also provides the X75 standard which describes the
rules for gateways between different networks. The
protocols used in CAMPS for gateway capabilities to
other communication systems are based on these standards.
These standards are also used when interfacing between
tactical and strategic networks,i.e. interoperability
between the networks. This concept is essential because
tactical networks might use different schemes. For
example, within NATO's European countries, EUROGROUP
has established standards, i.e. EUROCOM to be followed
for future tactical networks; Other standards might
be found in non-European systems.
3. M̲E̲S̲S̲A̲G̲E̲ ̲P̲R̲O̲C̲E̲S̲S̲I̲N̲G̲ ̲A̲N̲D̲ ̲E̲L̲E̲C̲T̲R̲O̲N̲I̲C̲ ̲M̲A̲I̲L̲
F̲e̲a̲t̲u̲r̲e̲s̲
Advantages in computer technology have 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 in 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
types of information. The automation functions pertaining
to message processing will yield many benefits when
implemented.
The concept of message processing and electronic mail
is based on the fact that many activities herein are
recurring and suited to automation. These activities
include:
- Drafting of messages with extensive correction
and restructuring
- Guidance in information entry
- Validation of message syntax, i.e. total structure,
substructure, length of lines, length of fields,
and type of fields.
- Coordination of message contents and subsequent
correction before approval.
- Schedule monitoring and reporting.
- Distribution of messages within an organization.
- Filing and retrieval of information.
- Remote connection between users and/or system.
The Systems Division of Christian Rovsing A/S now offers
a range of message processing and electronic mail systems.
S̲Y̲S̲T̲E̲M̲ ̲D̲E̲S̲C̲R̲I̲P̲T̲I̲O̲N̲
The introduction of modern visual display units, VDU's,
as replacements for typewriters or telex machines results
in immense improvement of the working situation for
message preparation personnel.
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 than earlier
offered on paper forms.
As an example of versatile VDU terminals consider the
one implemented by Christian Rovsing A/S in CAMPS.
This terminal can store up to 20,000 characters locally
before transmitting to the host.
The format mask is stored within the system and can
be retrieved immediately by the user without leaving
his workstation. The system can store many more different
masks or formats than are pratical in a manual environment.
The entered information will be checked for syntax
errors instantaneously and it will be checked for semantic
errors before acceptance by the system. This minimizes
human tasks required by message processing.
The types of syntactic checks include the quantity
of subset information or fields within the message.
No mandatory information can be forgotten. The system
will ensure that information which should be numerical
will be entered as such.
The semantic checks that can be performed are extensive.
Information which must belong to a larger known set
of information can be checked. For example, the name
of the recipient of a message can be validated as belonging
to the set of authorized names before final acceptance
of a message.
As soon as a messsage has been accepted by the system
from the drafters work station, it is processed automatically
without any delay. It has been already typed, so no
further entry by typist is required, and by electronic
mail facilities it can be conveyed to the recipient
in real time.
Reception of messages is the other aspect of message
processing, whether the recipient is a human being
or a computer system. In the traditional sense, where
people 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 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 identify final receivers, either
action or information receivers, as a function of the
subject of the messages. These rules can be programmed
into the message processing system to avoid mistakes
and time delays. An example is given in the CAMPS
description.
A modern message processing system will also assist
users in filing and retrieval of their messages. Many
different subject keywords can be used simultaneously
without necessitating duplication of physical files.
When messages are part of a larger 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 messages
to provide the decision maker with an overview. These
summaries might be provided on graphic terminals instead
of alphanumeric displays.
The overall organization of human efforts is an essential
part of computer assisted message processing. Within
a military organization the ability to distinguish
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
should immediately be informed of the arrival of any
urgent message at his terminal.
Likewise modern workstations can be connected to more
than one system and assist the user in the overall
performance of his work. The VDU's implemented in CAMPS
have 16 splits, i.e. 16 windows to the terminals memory
space. These splits could, in an expanded system, be
used for simultaneous communication with different
systems.
One of the aspects of message processing, introduced
above, is the gradual transition towards a paperless
society. This has many demands or security in a military
organization. First, the computer system checks who
has access to any information, and it logs all events
for later investigation, if required. Second, it minimizes
the need for paper copies and hence it diminishes the
risk of security leaks.
The results of electronic mail implementation within
the military community are very promising. Electronic
mail capabilities of modern data communication systems
are used to convey messages from one place to one or
several other places without delays due to human intervention.
This capability is now so fast that conference systems
can be set up, providing immediate response to any
message. Pseudo meetings can now be held with participating
members situated at geographically distant 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 dialogue between
two or more members continues as long as required.
To really understand the implication of electronic
mail implementation it might be illustrative to imagine
that anything which can be coded in numbers can be
transmitted from one place to another. Examples include
pictures like radar display data, maps, drawings, fingerprints
or voice in digitized formats. All these different
types of information can be transported over the same
transmission medium, giving great flexibility and survivability,
which are vital in a military environment.
The electronic mail capability can also provide the
user at his workstation with remote access to computer
systems. In the military environment, the aspect of
remote access can provide the tactical user at the
front access to a computer placed far behind the lines.
More specialized or dedicated computers can also be
accessed from remote locations. Systems which contain
spare part 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.
Expert systems, which apply 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 diagnosis by computer, aiding 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 computerized message
processing and electronic mail functions are farreaching
and hold many promises of immediately available benefits.
4. LOCAL AREA NETWORKS
F̲E̲A̲T̲U̲R̲E̲S̲
A local area network provides a common and economical
medium for interconnecting different terminal types
to one or more systems. Essential features are to:
- Provide flexibility in terminal placement within
a building and give easy relocation capabilities.
- Provide access to several dedicated computers within
the same or different local area networks from
the same terminal.
- Avoide nummerous point to point connection wires
between one computer and several terminals.
The System Division of Christian Rovsing A/S can install
local area networks tailored to your specific requirement.
S̲Y̲S̲T̲E̲M̲ ̲D̲E̲S̲C̲R̲I̲P̲T̲I̲O̲N̲
Instead of establishing costly multiple connections
between a computer and its terminals, 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, can be installed
in a building, going from room to room in the same
fashion as power outlets are provided in all rooms.
This can be done at building construction time or later
as a one time investment.
Once installed a local area network provides great
flexibility in actual placement of terminals. The terminals
can be moved freely and connected to the network via
the outlet placed in each room. No relocation costs
are involved.
The local area network allows connections of several
different types of terminal equipment. A small microprocessor
based terminal adaptor interfaces any old type of terminal
to the 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 be reached
by any terminal. For example, a person who works partly
with a text processing system, partly prepares 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 same local
area network.
If one of the computers attached to the network acts
as a gateway to long haul networks, then any terminal
user has access to all the services provided through
the long haul network.
The types of terminals that can be hooked up on a local
area network are not only human work-stations, but
any type of automatical sensing device which might
report its data through a local area network. Examples
are fire alarms, burgler alarms, equipment checkout
devices installed in local areas, buildings, aeroplanes,
ships etc. Not all of these examples apply to military
applications.
The ease of installation has been achieved by applying
a single, common transmission line throughout the area.
For relability reason this transmission media might
be dualized to provide back-up.
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. A local
area network is illustrated in Figure 4.
Figure 4
LOCAL AREA NETWORK
5. S̲E̲C̲U̲R̲E̲ ̲G̲A̲T̲E̲W̲A̲Y̲S̲
F̲E̲A̲T̲U̲R̲E̲S̲ ̲
Modern integrated Command Control and Communication
Information Systems (C…0e…3…0f…I) require secure and controlled
exchange of information between information processing
systems, networks, and work station. The exchange often
has to take place over inter-system boundaries that
do not match in terms of data formats, communication
protocols, and security levels.
A pratical solution is to introduce a GATEWAY betweeen
the different systems. The features of a Secure Gateway
need to be tailored to exact requirements. Examples
are:
- Conversion of possible differences in the communication
protocols and data formats between the two inter-linked
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.
S̲Y̲S̲T̲E̲M̲ ̲D̲E̲S̲C̲R̲I̲P̲T̲I̲O̲N̲
Christian Rovsing A/S have during the past years implemented
many systems that act as gateways between computer
systems, front ends between computer systems and networks,
and concentrators for terminals. The systems have
been based on the company's products inform of the
CR80 minicomputer and the (MP)…0e…2…0f… - MultiPurpose-MultiProcessor.
Typical examples of Gateway features are:
- a gateway that act as a transparent system passing
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 systems using different communications
protocols.
- a gateway that acts as a screening station validates
all traffic between two systems, and at the same
time performs 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 may typically be a simple
microprocessor system that does not need to take responsibility
for continuity in the traffic stream as this task is
handled by interconnected systems.
The second type of gateway will typically need to store
the information in the gateway for the period required
for the converter to take over responsibility for the
information during the transfer and perform normal
acknowledgements to the two inter-linked systems.
The structure of a typical gateway to be used for transfer
of message traffic is shown in figure 5. The software
is structured in accordance with the protocol levels
and consists of:
- a level handling the data link control signals.
- a level handling a link access protocol to ensure
an error free transfer of data frames from system
to gateway.
- a level handling 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
in …86…1 …02… …02… …02… …02…
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 where it was interrupted.
- a level for 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.
- a level that provides all 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 this level would also include
a message analysis facility and/or an interface
to a visual display unit (VDU).
Figure 5
SECURE GATEWAY
showing the functional layout
6. V̲I̲E̲W̲D̲A̲T̲A̲ ̲
Viewdata is a facility for retrieving information from
computer data bases. The information is stored in "pages"
in the Viewdata 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.
Christian Rovsing A/S produces a Viewdata System -
VIDEOTEX - which is described in section III.
