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APPENDIX
1 OF VOL
IV
1982-03-05
MESSAGE
SUBSYSTEM
Page
#
TECHNICAL
PROPOSAL
…02…. M̲E̲S̲S̲A̲G̲E̲ ̲S̲U̲B̲S̲Y̲S̲T̲E̲M̲ ̲D̲E̲S̲C̲R̲I̲P̲T̲I̲O̲N̲
The technical solution proposed by Christian Rovsing
A/S for the Message Subsystem applies state-of-the-art
technology and the latest communications techniques
to structure an integrated hardware/software system.
The proposed system has been configured after a thorough
analysis of the quantitative and functional requirements,
and the resulting system is fully responsive to operational
needs and meets all the security, reliability and expandability
requirements stated in the IFB.
This volume, the technical proposal, presents the hardware/software
system proposed for the Message Subsystem, and the
following is a brief description of each section:
Section 1 - H/W & S/W configuration overview,
performance overview, functional
highlights and a description of
the external interfaces of the Message
Subsystem.
Section 2 - operational procedures.
Section 3 - general H/W and S/W technical specification
including considerations of reliability
and security.
Section 4 - detailed description of the proposed
hardware/software solution in terms
of the technical requirements.
Section 5 - line circuit standards and external
interfaces.
Section 6 - logistics support including such
items as installation, training,
documentation and maintenance.
Section 7 - acceptance test program.
Section 8 - optional items.
1.1 C̲o̲n̲f̲i̲g̲u̲r̲a̲t̲i̲o̲n̲ ̲O̲v̲e̲r̲v̲i̲e̲w̲
The proposed design of the Message Subsystem has been
based on a thorough analysis of the quantitative and
functional requirements listed in the IFB; the resulting
system is fully compliant with all requirements. Additionally,
it should be noted that the design has benefited from
experience in designing and implementing similar communications
systems - FIKS and CAMPS.
Fig. 1.1-1
TELEGRAPH MESSAGE SUBSYSTEM OVERVIEW
The Message Subsystem, as shown in figure 1.1-1, is
one of three subsystems of the Telegraph Message Subsystem;
the other two subsystems are the Ship-to-Shore Subsystem
and the Broadcast Subsystem. In terms of function,
the Message Subsystem (MS) provides message switching
services for network users; the Ship-to-Shore Subsystem
provides communication facilities for the receipt of
message traffic from ship based commanders; and the
Broadcast Subsystem provides communication facilities
for the transmission of messages to ship based commanders
and other authorities.
In further detail, the MS consists of the Message Processing
Facility (MPF) - providing message switching and of
the Message Compilation Unit (MCU) - providing message
assembly.
The MPF - serving a variety of communication systems
and circuits by which ship and shore based commanders
can exchange messages - is connected to the following
external communication systems (interfaces to the MPF
are shown in fig. 1.1-2, the numbers refer to number
of lines):
o ship-to-shore circuits by which messages from ships
are received in multi-copies and compiled to one
reliable message by the MCU
o Broadcast circuits by which messages are broadcast
to ships and other authorities.
o Maritime Rear Links (MRL's) by which point-to-point
transmission and reception of messages are provided
to and from ships and other authorities.
o NICS-TARE circuits providing access to shore based
commanders
o TRC circuits providing point-to-point connection
to shore based commanders.
Fig. 1.1-2
MESSAGE SUBSYSTEM INTERFACE OVERVIEW
Message entry and supervision of message traffic are
carried out on local terminals which are connected
to the MPF. The following terminals are supported:
o MCSF workstations consisting of a VDU and a printer
- both Tempest certified. The MCSF workstation
is in the MCSF room.
o Supervisor position consisting of a VDU and a printer.
o Message Service Positions (3) consisting of 3 VDU's
and 1 printer.
All message formats together with the rules and procedures
for message exchange - via the MPF and over the communication
lines - are in accordance with ACP 127, NATO supplements
1 and 3 or with ACP 126, modified. The MPF will convert
all messages received in ACP 126 format into ACP 127
format before retransmittal.
All delivered equipment for the MPF - except the MCSF
terminal - will be placed in the red area in the shielded
room. All communication lines leaving the MPF room
are security protected by use of crypto equipment except
for the colocated NICS-TARE connection which uses a
secure wire. The MCSF terminal, which is placed in
the MCSF room, is connected to the MPF via secure optical
cables.
Patch, test, traffic monitoring and terminal reconfiguration
may be performed at the line termination unit interface
by disconnecting cable/opto cables.
It must be emphasized that on-line monitoring of traffic
is not foreseen, since built-in equipment monitoring
is taking care of error/degradation eletection.
Channel assignment to physical terminals is likewise
a software faiclity.
Four MCU's connect the four MPF Ship-to-Shore receive
channels to the 16 Ship-to-Shore circuits. This connection
is shown in figure 1.1-3.
Each MCU evaluates the message stream received from
the circuits (emanating from a single source) and combines
them into a single output stream with erroneous or
suspect messages identified through control information
so that they may be taken into account by the MPF message
handling. The resultant character data stream is delivered
by the MCU to the MPF via crypto equipment for decryption.
Fig. 1.1-3
CONNECTION BETWEEN SHIP-TO-SHORE
SYSTEM AND MESSAGE SUBSYSTEM
The Message Processing Facility (MPF) functions provide
the store and forward message switching services for
the CROSSFOX system. These functions are schematically
shown in figure 1.1-4 indicating the principal message
flow through the MPF and the related functions.
The main function to be performed by the MPF is the
automatically relaying of incoming messages:
- Incoming traffic from Ship-to-Shore, NICS-TARE,
TRC or MRL is properly received, analysed and stored
in the data base. The analysis is in accordance
with ACP 127 or ACP 126 formats and rules.
- The incoming messages are routed in accordance
with address information contained in each message
and the routing directives given by the supervisor.
- The messages are converted to comply with ACP 127
formats before they are sent over the outgoing
channels, such as Broadcast, NICS-TARE, TRC or
MRL.
- Each channel is controlled with respect to availability,
quality and accountability.
- Messages will be either controlled automatically
or controlled manually by the supervisor.
The message traffic through the MPF is serviced by
auxiliary functions such as message storage and retrieval,
statistical collections and logging of messages and
transactions.
The MPF facilitates a man/machine interface via which
operators can supervise and control the message traffic
and via which users can enter and receive messages.
The operators/users of the system are:
- The supervisor who controls the message traffic
flow and the message processing.
Fig. 1.1-4
MPF SYSTEM OVERVIEW
- The message service operators who are requested
to take action when the automatic processing of
incoming and outgoing messages fails due to erroneous
messages.
- The engineering operator who controls the H/W
configuration of the system.
- The MCSF user who can enter and receive messages
to/from external communication systems.
The MPF is connected to a stand-by MC where messages
and status information are exchanged with the MPF in
the stand-by MC. A change-over to the stand-by system
is done automatically once initiated by the supervisor.
The MPF is designed to be a secure system. Unauthorized
persons cannot gain access to the system. Security
functions are embedded in the individual functions.
The hardware configuration proposed for implementation
of the functions performed by the MPF is shown in simplified
form in figure 1.1-5. The heart of the configuration
is the CR80 FATOM, a fault-tolerant system with superior
expandability and reliability characteristics developed
by Christian Rovsing A/S. The CR80 FATOM is a totally
dualized computer with two identical processor units,
a channel unit and a watchdog processor. The processor
unit contains devices such as CPU's with cache, Direct
Memory Access (DMA) and memory (RAM). The channel unit
contains all modules for connection of peripherals,
such as disks, floppy disk and line termination units
for connection of internal and external communication
lines. All modules are attached to buses, providing
communication between all modules. The watchdog processor
interfaces to both the processor units and the channel
unit for purposes of status monitoring and control
of these units.
Fig. 1.1-5
MPF HARDWARE CONFIGURATION OVERVIEW
The engineering operator interfaces are provided by
a VDU and a printer attached to the watchdog and a
floppy disk attached to the channel unit.
The communication lines provided for the MPF are connected
to the LTU's in the channel unit. Local terminals
are directly connected except for the MCSF terminals
which are connected via a secure optical fiber link.
All external lines are connected via a crypto equipment,
except for the NICS-TARE line where a secure wire is
used. On the lines for Ship-to-Shore, the Message
Compilation Unit will assemble all received messages.
The Message Subsystem outlined above will be described
in significant detail in the following sections.
1.2 P̲E̲R̲F̲O̲R̲M̲A̲N̲C̲E̲ ̲O̲V̲E̲R̲V̲I̲E̲W̲
The CROSSFOX configuration proposed by Christian Rovsing
will perform safely within the performance limits put
forward in the IFB.
The proposed configuration will satisfy all requirements
for throughput, storage, and reponse time when exposed
to continuous peak traffic load corresponding to the
maximum character transfer rates (channel capacities)
on all specified external channels. Even with a 30
percent expansion of this traffic, i.e. the IFB requirement
for expansion without hardware or software changes,
the requirements will be fulfilled.
The traffic flow used for estimating the system performance
is partly taken directly from the IFB and partly derived
via conservative assumptions. Refer to section 4.7.1
for a detailed presentation of the traffic flow figures.
Fig. 1.2-1 presents the traffic flow corresponding
to the maximum character flow and with indication of
the relative distribution of incoming and outgoing
traffic. The number of outgoing messages is equal
to the number of incoming messages, thus reflecting
the fact the MPF is a relay facility. The excess character
rate on outgoing channels as compared to incoming traffic
channels is "used" for multiple transmission of the
same message.
The way each of the performance requirements have been
fulfilled will be discussed in details in section 4.7.
The following subsections will first repeat the requirements
and then present the results of section 4.7.
1.2.1 C̲o̲n̲n̲e̲c̲t̲i̲v̲i̲t̲y̲ ̲a̲n̲d̲ ̲T̲h̲r̲o̲u̲g̲h̲p̲u̲t̲.̲
a) The system connectivity may be documented by the
following facts:
- The input character rate corresponding to the
maximum possible character transfer is 242
char/sec (refer to fig. 1.2-1).
The output rate is maximum 478 char/sec.
The total is thus 720 char/sec. Considering
the expansion requirement of 30% for the traffic
rate the result is about 1000 char./sec.
- The figure of 1000 char/sec is easily handled
when compared to the capacity of a single LTU
of 19,200 bit/sec. and the maximum transfer
rate to/from the I/O buses of 4 MBytes/sec.
- An additional requirement for a total throughput
rate of 600 char/sec. incoming and 800 char/sec.
outgoing is seen to be easily fulfilled.
- Each LTU accepts a maximum of 4 channels, which
allows for a maximum channel transfer rate
of 4800 bit/sec. (as a minimum).
- The configuration has been equipped with 11
LTUs thus providing connections for a 25 per
cent expansion of any type of internal or external
connections - also taking into consideration
the differences in line protocols. Additionally
7 more LTU's can be attached to the two I/O
crates provided.
Fig. 1.2-1
b) The throughput capabilities of the system have
been checked by calculating the PU and the disk
system load in two cases thus yielding the excess
capabilities of the system:
1) The traffic corresponding to the continuous
maximum possible input and output character
rates (the case of fig. 1.2-1) plus 30 per
cent expansion will result in the following
loads:
- each CPU approx. 32 per cent
- the mirrored disks approx. 55 per cent.
2) The loads in the case of 600 char/sec input
and 800 char/sec output-assuming the same relative
flow of traffic in fig. 1.2-1 - are found as:
- each CPU approx. 42 per cent
- the mirrored disks approx. 75 per cent
Full processing has been assumed, i.e. continuous
flow, although these character rates are specified
to last for only 5 minutes according to the
IFB.
1.2.2 S̲t̲o̲r̲a̲g̲e̲
The needs for disk storage capacity have been estimated
on basis of the following determining factors:
1) The on-line storage period for messages must be
at least 7 days
2) Each relayed message must be stored in two (2)
formats, the incoming format and the outgoing format.
3) 30 per cent traffic expansion must be accommodated
without additional hardware.
It has been found that the requirement for 30 per cent
expansion makes it necessary to provide a storage capacity
of about 80 M Bytes unformatted storage. Consequently
Christian Rovsing A/S has proposed a mirrored set of
disks with each disk having a capacity of 150 MBytes
unformatted storage (approx. 125 MBytes formatted).
For the off-line disk a capacity of 80 MBytes (66 MBytes
formatted) is sufficient. 5 disk packs will be needed
for 30 days off-line storage.
It is seen that the IFB requirement (section 5.1.2.7.1)
for 20% spare for immediate access (mirrored disks)
and backing storage (off-line disk) is fulfilled as
well.
However, 80 MBytes disks might be used for the mirrored
pair of disks provided the second requirement concerning
the storage of the same message in two versions will
be changed as follows:
Each message will be stored in one format containing
the information of the incoming message and with addition
of the retransmission information of the corresponding
outgoing message(s). On retrieval the message may
be displayed in a format very similar to the incoming
format.
A relaxation of the first requirement as follows will
lead to selection of smaller disks: The on-line storage
period is determined by the size of the disk storage
capacity and a threshold for storage is defined so
that exceeding this storage limit sends a warning to
the supervisor.
The average on-line storage period will be about 7
days for 80 Mbyte disks without the expansion of traffic.
Consequently a third possibility is given for an interpretation
which allows the use of 80 Mbyte disks: The 30 per
cent expansion rule does not require the rule of 7
days on-line storage to be kept.
1.2.3 R̲e̲s̲p̲o̲n̲s̲e̲ ̲T̲i̲m̲e̲s̲
The system will perform within the response time limits
of the IFB even in the case of continuous maximum character
transfer rates on external channels plus a 30 per cent
expansion. The traffic flow is assumed to be the one
presented in section 1.2.
The requirements to be fulfilled may be divided into
three categories.
1. Cross-office handling time, COHT. The COHT shall
apply from the receipt of EOM until the message
is converted for transmission. No service action
is assumed. (The COHT may also indicate delivery
to local terminals. Since the processing requirements
here are less, this case has been ignored):
Four requirements have been specified:
- General message: 10 sec. 99% of cases
- General message, FLASH: 5 sec. 99% of cases
- General message: 20 sec. maximum
- ACP 126 message: 5 sec. maximum
2. Interactive processes at local terminals:
- General Commands: Validation response within
1 sec for 90% of cases.
- Supervisor Commands: Validation response within
1 sec. for 99% of cases, maximum 2 sec.
3. Retrieval times from initiation of retrieval (request)
and until the message is available for transmission
or display:
- on-line: maximum 10 sec.
- off-line: maximum 10 minutes (not including
time for volume mounting).
1.3 F̲U̲N̲C̲T̲I̲O̲N̲A̲L̲ ̲H̲I̲G̲H̲L̲I̲G̲H̲T̲S̲
The Message Subsystem (MS) will provide an automated
interface between the NICS TARE and the CROSS FOX HF
and LF radio telegraph systems. It will provide relaying
of ACP126/ACP127 messages between ship-borne and shore-based
users and will hereto facilitate management/supervision
and security of the message traffic.
The MS functions match, to a high degree, the functions
of the Computer Aided Message Processing System, CAMPS,
presently being implemented by Christian Rovsing A/S
for NATO. In addition to basic CAMPS functions, CROSSFOX
further includes a number of special Maritime Message
Handling functions to handle broadcast and reception
over radio-links, to secure message delivery, and to
provide accountability.
This section will list the main functional requirements
for the Message Processing Facility (MPF) and the Message
Compilation Unit (MCU) with respect to security, relay
of messages, management of communication channels,
supervisory control of message traffic and message
assembly.
1.3.1 M̲P̲F̲ ̲F̲u̲n̲c̲t̲i̲o̲n̲s̲
The main facilities and functions to be provided by
the MPF are:
a) To receive and analyze messages in ACP127 format
from any of the communication channels.
b) To receive and analyze messages in ACP126 (modified)
format from the Ship-to-Shore system and from the
MRLS.
c) To automatically translate messages received in
ACP126 (modified) into ACP127 before relaying them
(retransmission) to any of the communication systems.
d) To process and route received messages based on
address information in the message and in accordance
with the rules and procedures laid down in ACP127
and in the IFB.
e) To transmit messages to ships via the Broadcast
system and/or an MRL, to sites via the collocated
NICS TARE and/or TRC, and/or to local users via
directly connected terminals according to the routing
information in each message.
f) To make a reduced ACP126 to ACP127 conversion of
messages received in ACP126 (modified) format,
before relaying. This will apply to messages with
RI's included in a supervisor specified list.
The reduced conversion includes enveloping the
ACP126 formatted message with an ACP127 header.
g) To provide on-line message storage for 7 days of
traffic and off-line storage for up to 30 days
of message traffic with facilities for both on-line
and off-line retrieval.
h) To account for all messages received, transmitted,
or prepared by producing log records for each message
on a per channel or terminal basis. The log record
will be printed out.
i) To produce a hard copy log record of all important
system actions and terminal transactions for security,
accounting, and recovery purposes. In addition
to produce a hardcopy of incoming or outgoing message
traffic, if wanted, on a channel basis.
j) To provide capabilities for message delivery and
service message preparation at local terminals
placed in the MCSF area (one terminal) and the
MPF area (four terminals). An interactive dialog
will assist the user in preparation of a message.
k) To provide comprehensive supervisory and control
facilities and a suitable engineering operator
position for effective control and operation of
the MPF including start up, recovery, and maintenance.
l) To provide message service operator positions with
appropriate facilities for message service and
other functions, such as:
o message retrieval
o message servicing
o maintenance of routing and address information
o management of Ship-to-Shore channels
o screening and vetting of messages destined
for broadcast
o routing assistance for messages when format
translation cannot be fully effected
o routing of messages for broadcast containing
special RI.
m) to exchange accounting information periodically
with CROSS FOX ship users and shore users to protect
against loss of traffic.
n) To compile and periodically print out traffic statistics.
o) To be capable of handling at least 2000 incoming
and 2000 outgoing messages per day with an average
length of 1500 characters each.
p) To meet the user response time requirements for
the cross-office handling time and the response
time requirements for command entry and message
retrieval.
q) To provide for future expansion; 30% increase
in future message traffic and 25% increase in the
total number of local terminals and external communication
lines without hardware and S/W changes.
r) To provide for the exchange of updating information
between the controlling and stand-by MPF.
1.3.2 M̲C̲U̲ ̲F̲u̲n̲c̲t̲i̲o̲n̲
The Message compilation Unit receives four serial data
streams from four ship-to-shore access sites. The
four data streams are identical except for transmission
errors and delay.
A single message is compiled from the four data streams
using a majority voting algorithm. This message is
conveyed to the MPF through a KW-7 crypto.
In addition, character and channel status are supplied
directly to the MPF.
1.4 E̲X̲T̲E̲R̲N̲A̲L̲ ̲I̲N̲T̲E̲R̲F̲A̲C̲E̲S̲
A number of different communication systems are connected
via the Message Subsystem to facilitate communication
between ship-borne and shore commanders. Most of these
interfaces are presently being implemented by Christian
Rovsing A/S in other NATO and national programs such
as CAMPS and FIKS.
The Message Subsystem is the interconnection point
between a number of different ship-borne and shore
communication systems. It provides common facilities
for message relaying via the following interfaces:
- NICS TARE
- TRC/POINT-TO-POINT-CONNECTION
- BROADCAST SUBSYSTEM
- SHIP-TO-SHORE SUBSYSTEM
- MARITIME REAR LINKS
Furthermore a connection between the primary and the
standby Management Center is provided.
Christian Rovsing A/S are in the position of having
developed the interface procedures and protocols at
the lower levels for the interface to NICS TARE and
TRC/POINT-TO-POINT Connections.
The format of the messages will conform to ACP-127
NATO SUPP-3 or to ACP-126 modified. The software to
analyse and generate the ACP-127 format are already
developed for use in other NATO systems.
The interface control procedures and formats are laid
down in a number of protocol levels, identified as
message level, link access level and electrical interface
level.
In the following, the terms circuit and channel are
of logical nature, whereas line is the actual physical
implementation of a channel. A circuit may have one
or more channels associated; outgoing message traffic
is always queued for a circuit followed by transmission
over a channel according to a simple algoritme, e.g.
first channel available in a certain order.
The interfaces defined below represent the demarcation
line between the MPF and the line equipment (modems,
crypto's and crypto control boxes) described in the
main proposal.
1.4.1 N̲I̲C̲S̲-̲T̲A̲R̲E̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲
The main access to shore based commanders is provided
by the Message Subsystem via direct link to a colocated
NICS-TARE. The interface protocols are:
- CCITT's recommendation V24/V28 low level interface
describing the circuits and electrical signals
to be used.
- LITSYNC Error Detection and Correction (EDC) link
level protocol already implemented by Christian
Rovsing A/S.
- Message formats and transmission controls such
as channel continuity check and channel opening/closing
procedures are in accordance with ACP127 Supp.
3.
The interface will consist of one full duplex channel
with a transmission rate of 600 bits/sec. The Message
Subsystem will have capacity for one spare channel
of this type. More details on the interface description
are given in section 5.1 of this appendix.
1.4.2 T̲R̲C̲/̲P̲o̲i̲n̲t̲-̲t̲o̲-̲P̲o̲i̲n̲t̲ ̲C̲o̲n̲n̲e̲c̲t̲i̲o̲n̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲ ̲
The Message Subsystem will also provide access to shore
commanders via the TRC/Point-to-Point Connections.
The interface protocols are:
- CCITT's recommendation V24/V28 low level interface
describing the circuits and electrical signals
to be used.
- Message formats and transmission controls such
as channel continuity check and channel opening/closing
as laid down in ACP127 Supp 3.
The interface to TRC/Point-to-Point Connection is provided
with six full-duplex circuits with a rate of 50 of
75 bps. More details on this interface description
are given in section 5.2 of this appendix.
1.4.3 S̲H̲I̲P̲-̲t̲o̲-̲S̲H̲O̲R̲E̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲
Messages from ships are received via 16 logical circuits
connecting the ship-to-shore subsystem with the Message
Subsystem. To ensure reliable reception of messages,
each message is transmitted simultaneously on 4 circuits.
The interface protocols are:
- CCITT's recommendation V24/V28 low level interface.
- Message formats and transmission control in accordance
with ACP127, Supplement 1 and 3, and ACP126 modified.
The 16 simplex circuits will have a transmission rate
of 75 bps. Further details are given in section 5.4
of this appendix.
1.4.4 B̲r̲o̲a̲d̲c̲a̲s̲t̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲
For the purpose of transmitting messages to ships from
shore based commanders the Message Subsystem provides
8 circuits to the Broadcast Subsystem. The interface
protocols are:
- CCITT's recommendation V24/V28. Low level conversion
is performed by the crypto control box before leaving
the shielded area.
- Message formats and transmission control are in
accordance with ACP127, supplement 1 and 3.
The simplex circuits are connected to crypto equipment
capable of transmitting 75 bps. Further details are
given in section 5.3 of this appendix.
1.4.5 M̲a̲r̲i̲t̲i̲m̲e̲ ̲R̲e̲a̲r̲ ̲L̲i̲n̲k̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲
Bidirectional communication between shore and ship-borne
commanders can be achived by the interface to the Maritime
Rear Links. The interface consists of two full-duplex
circuits. The interface protocols at the MPF level
are
- CCITT's recommendation V24/V28.
- Message formats and transmission control are in
accordance with ACP127, Supp. 3 and ACP126 modified.
Each circuit is connected to a KW7 type equipment
and the transmission speed is 75 bps. More details
are given in section 5.5.
- Each MRL will be operated identically to a single
channel SHIP-to-SHORE circuit combined with a single
channel of the BROADCAST.
1.4.6 S̲t̲a̲n̲d̲b̲y̲ ̲M̲C̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲
One full-duplex circuit of 1200 bps available for the
MPF will be provided to be used to exchange message
traffic for "standby" purposes with the other MC.
The protocols are:
- CCITT's recommendation V24/V28 low level interface
- EDC LITSYNC link level protocol
BID 1000 is used as the crypto equipment for this line.
More details are given in section 5.6 of this appendix.
