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CHAPTER 4
Page #
DOCUMENT III TECHNICAL PROPOSAL Apr. 29, 1982
4.5 S̲e̲c̲u̲r̲i̲t̲y̲ ̲S̲y̲s̲t̲e̲m̲
The security system provides means for access control
to the services offered by the network. The Services
are the applications and the data bases of the host
computers connected to the network. The security access
control is performed against the users when signing
on to the network services. The host security and the
ACDN Security requirements are combined into a common
user profile.
4.5.1 G̲e̲n̲e̲r̲a̲l̲ ̲S̲e̲c̲u̲r̲i̲t̲y̲ ̲A̲s̲p̲e̲c̲t̲s̲
Service access control is applicable to
o Users
o Terminals
Terminal access control is applicable to users.
Thus access to a service is granted when:
1) The user has access to the terminal
2) The terminal has access to the service
3) The user has access to the service
4) Correct sign-on procedure is performed
It is obvious that access to security data can only
be obtained by operators with a higher security level
than the users of the security data.
4.5.2 D̲i̲s̲t̲r̲i̲b̲u̲t̲i̲o̲n̲ ̲o̲f̲ ̲S̲e̲c̲u̲r̲i̲t̲y̲
The principles for the distribution of security is
given on table 4.5.2-1.
A subscribing department/agency is characterized by
the following:
o Users (i.e. operators)
o Allocated terminal equipment
o Services subject for subscription
As appears from the table the access rights to the
a̲g̲e̲n̲c̲y̲ of terminals and services is allocated by the
network administration.
The access rights to the u̲s̲e̲r̲s̲ of terminal and services
are allocated by the "Local Office Manager".
Users have access to their own Id and password only.
Subscribing Profile User Local Network
Agency/Depart. (level 0) Office Super-
Characteristics (Level 1) visors/Adm.
(Level 3-4)
Local
Office Security
Mgr. Profile
Users User 1 Security
Profile
User 2 o Id x x
. o Password x x
. o Service
. Access x
. Record
User n o Terminal
Access
Record x
Terminal
Profile
Terminal 1
o Agency
Terminals, . access
equipment . record x
. o Service
. Access
. record x
Terminal m
o Terminal
designa-
tions x
Service 1 x
. x
Services . x
. x
Service n x
Table 4.5.2-1
Security Distribution
4.5.3 S̲i̲g̲n̲-̲O̲n̲ ̲S̲e̲c̲u̲r̲i̲t̲y̲ ̲S̲y̲s̲t̲e̲m̲ ̲P̲r̲o̲c̲e̲d̲u̲r̲e̲
The user-id/password is a mandatory parameter in the
ACDN log on message. Based on the user-id, the user
profile entry is looked up in the NCC by the Network
Access Services. Several steps of validation occur.
o Check valid user-id, i.e. is an entry found in
the list of user profiles.
o Check password
o If the user profile specifies a set of terminals
which the user is allowed to use, check that the
actual terminal-id is included in the list.
o Look up the terminal profile based on terminal-id.
o If the terminal profile specifies a set of users
who are authorized to use that particular terminal,
then check that user-id is included in the set.
o Finally, if the user profile specifies a set of
allowed applications, then check that the application
name is present in the set.
If the validation fails the user is not granted access
and the event is recorded in the Logfile. The maximum
number of unsuccessful logons, which the system will
tolerate can be specified. If this threshold is passed
an alarm is given. The terminal is deactivated and
the user-id is marked invalid.
4.5.4 M̲a̲i̲n̲f̲r̲a̲m̲e̲ ̲A̲c̲c̲e̲s̲s̲ ̲S̲e̲r̲v̲i̲c̲e̲s̲
A basic service provided by the host access software
is the ability to access application programs contained
in IBM, Univac and Honeywell mainframes. This proposal
is based on extensions to existing software to support
multi sign in capabilities needed by AIR CANADA. The
ability to access the application programs is dependent
on the IBM and Univac mainframes being designated as
participatory members belonging to the ACDN. In the
following, we will assume this to be true and use the
work mainframe or host synonymously with participant.
The access procedure consists of two levels. At the
first level, the user identifies himself to the ACDN
and gets validated for access.
At the second level, the user identifies himself to
the application program in a host, and gets accepted
for access.
The access is based on LOGON and LOGOFF commands as
described below:
LOGON: IBM devices perform a Logon to an SNA network
on one of the two ways:
i) Via an INITIATE-SELF-SNA-command
ii) Via a character coded Logon:
LOGON APPLID (prog-name) LOGMODE (mode)
DATA (user-data).
Terminal users log on via a character coded Logon containing
the following information:
LOGON USER (user-id/password)
HOST (host-id PROG (prog-name) DATA (user-data)
User-id is mandatory. It identifies uniquely the user
and gives an entry to the user profile in the NCC.
The other parameters can be:
- specifies as shown
- defaulted to a value found in the user profile
or derived from the status (e.g. host-id derived
from prog-name)
- prompted by the NCC after Logon to ACDN has been
performed.
When validation of the user, Logon to ACDN and collection
of the remaining parameter values have been performed,
the user can be signed on to the application program.
The application may interpret user-data as a host system
dependent user-id/password, which then will be different
from that used by ACDN.
If a user (terminal or application) issues a connection
request to a given terminal then the connection cannot
be established until the terminal is available and
a user has logged on to ACDN.
If the terminal is available, but no user is logged
on, a message identifying the requesting user will
be output to the terminal. When a user logs on the
terminal, the connection is established.
4.5.5 T̲e̲s̲t̲ ̲S̲y̲s̲t̲e̲m̲ ̲A̲c̲c̲e̲s̲s̲
Test environment security is accomplished simply by
assignment of a test subscriber with users having private
access to test terminals and test services only.
4.5.6 N̲e̲t̲w̲o̲r̲k̲ ̲I̲n̲t̲e̲g̲r̲i̲t̲y̲
The ACDN software integrity is maintained by protecting
the software entities from unauthorized changes. This
protection is provided partly softwarewise, partly
hardwarewise. No operator, no user will possess a profile
which gives access to a capability class where a change
of software will be possible.
4.6 O̲p̲e̲r̲a̲t̲i̲o̲n̲s̲ ̲C̲o̲m̲m̲a̲n̲d̲ ̲S̲u̲m̲m̲a̲r̲y̲
The ACDN network operations are controlled primarily
through operator command input entered at the NCC supervisor
positions. However, other sources of network operations
commands exists.
For the purpose of providing an overview, the complete
suite of man-machine commands identified as necessary
for controlling the proposed ACDN and providing the
required facilities has been summarized in overleaf
table 4.6.
Each possible command corresponds to one line in the
table. The overview tables do not identify the necessary
command input parameters. These are specified in subsequent
sections with the more detailed command descriptions.
For each command it has been identified (by a x) from
which subsystem type (e.g. NCC, Node, etc.) the corresponding
command may originate, and further the required authority
level (ref. section 4.5) associated with the command.
The command are listed in the following groups:
o Local Subsystem Initialization (4.6.1)
o NCC Control Commands (4.8.5.2)
o Node control (4.8.5.2)
o Link control (4.8.5.3.1)
o Internal control (4.8.5.3.2)
o Resource utilization (4.8.5.3.3)
o Line control (4.8.5.4.1)
o Concentrator control (ICC) (4.8.5.4.1)
o Device control (terminal and printers) (4.8.5.4.2)
o Host network appearance control (4.8.5.4.3)
o Conversation and Session Control (4.8.5.5)
o Event control (4.8.6.2)
o Online table update (4.8.6.3)
o Test control (4.8.8/4.14)
o User control (4.8.11)
o Statistics control (4.8.9.1)
o Report generation (4.8.9.2)
o TDP print control (4.8.10.1)
o PMS control (4.8.10.2)
The individual commands in a group are described in
the indicated section.
COMMAND LOCATION AUTHORITY
N N N E U A S L T U
M C O M S D U O E S
H C D H E M P M C E
E R H R
L̲O̲C̲A̲L̲ ̲S̲U̲B̲S̲Y̲S̲T̲E̲M̲ ̲I̲N̲I̲T̲I̲A̲L̲I̲Z̲A̲T̲I̲O̲N̲
C̲O̲M̲M̲A̲N̲D̲S̲ ̲(̲T̲O̲S̲)̲ x x x x
x
x
N̲C̲C̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
NCC Offline x x
NCC Standby x x
NCC Active x
x
N̲O̲D̲E̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
include NODE x x
exclude NODE x x
include local network x x
x
exclude local network x x
x
status node x x
L̲I̲N̲K̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
include link (TRUNK) x x x
exclude link (TRUNK) x x x
status link (TRUNK) x x x x
I̲N̲T̲E̲R̲N̲A̲L̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
initiate VC x x x
terminate VC x x x
status VC x x
x
R̲E̲S̲O̲U̲R̲C̲E̲ ̲U̲T̲I̲L̲I̲Z̲A̲T̲I̲O̲N̲ ̲C̲O̲N̲T̲R̲O̲L̲
C̲O̲M̲M̲A̲N̲D̲S̲:̲
buffer limit x x
session limit x
x
routing status x x
x
x
Table 4.6 Command Summary
COMMAND LOCATION AUTHORITY
N N N E U A S L
T U
M C O M S D U O
E S
H C D H E M P M
C E
E R
H R
L̲I̲N̲E̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
include line x x x
x
exclude line x x x
x
poll line x x
x
x
skip line x x
x
x
hold traffic to line x x x
x
release traffic to line x x x
x
status line x x x
x
C̲O̲N̲C̲E̲N̲T̲R̲A̲T̲O̲R̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
include station (ICC) x x
x
x
exclude station (ICC) x x
x
x
poll station (ICC) x x
x
x
skip station (ICC) x x
x
x
hold traffic for station (ICC) x x x
x
release traffic to station (ICC) x x x
x
status station (ICC) x x x
x
reset station x x
x
x
backup station x x
x
x
normal station x x
x
x
backup RLMG x x x
x
normal RLMG x x x
x
up LPMC x x x
x
down LPMC x x
x
x
D̲E̲V̲I̲C̲E̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
include device x x
x
x
exclude device x x
x
x
poll device x x x
x
skip device x x x
x
hold traffic to device x x
x
x
release traffic for device x x x
x
status device x x
x
x
H̲O̲S̲T̲ ̲N̲E̲T̲W̲O̲R̲K̲ ̲A̲P̲P̲E̲A̲R̲A̲N̲C̲E̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
vary x x x
display x x x
Table 4.6 Command Summary (cont'd)
COMMAND LOCATION AUTHORITY
N N N E U A S L
T U
M C O M S D U O
E S
H C D H E M P M
C E
E R
H R
C̲O̲N̲V̲E̲R̲S̲A̲T̲I̲O̲N̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
initiate conversation x x
x
interrupt conversation x x
x
Resume conversation x x x
terminate conversation x x
x
status conversation x x x
initiate session x x x
interrupt session x x
x
resume session x x
x
termination session x x x
status session x x
x
E̲V̲E̲N̲T̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
scan event x
x
print event log x x
acknowledge event x
x
browse event log x x
O̲N̲L̲I̲N̲E̲ ̲T̲A̲B̲L̲E̲ ̲U̲P̲D̲A̲T̲E̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
update network table x x x x
update user profile table x x x
enter security record x x
x
change security record x x
x
delete security record x x
x
enter temporary assignment x x x
delete temporary assignment x x x
change password x x x x
x x
select new password x x x
unlock security record x x
x
block security record x x
x
free security record x x x
change authority code x x
x
update terminal profile x x x
update application table x x x
T̲E̲S̲T̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
loop x x x
x
bounce x x x
x x
trace on x x x
x
trace off x x
x
x
dump x x x
x
read memory x x x
x
Table 4.6 Command Summary (Cont'd)
COMMAND LOCATION AUTHORITY
N N N E U A S L
T U
M C O M S D U O
E S
H C D H E M P M
C E
E R
H R
U̲S̲E̲R̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
sign on x x x x
x x
sign off x z x x
x x
sign out remote x x x
x x
broadcast x
x
x
connection status
x
x
x
x
x
display network errors x x
x
x
x
x
info x x x
x x
Display TDP status
x
x
x
x
x
S̲T̲A̲T̲I̲S̲T̲I̲C̲S̲ ̲C̲O̲N̲T̲R̲O̲L̲ ̲C̲O̲M̲M̲A̲N̲S̲:̲
statistics file x x x
print statistics x x x
start statistics x x x
stop statistics x x x
accounting file x x x
R̲E̲P̲O̲R̲T̲ ̲G̲E̲N̲E̲R̲A̲T̲I̲O̲N̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
print message statistics report x x x x
x
print traffic statistics report x x x x
x
print system report x x x x
x
print response time report x x x x
x
print line status report x x x x
x
print terminal status report x x x x
x
print routing status report x x x x
x
print system queue report x x x x
x
print network error report x x x x
x
print TDP status report x x x x
x
T̲D̲P̲ ̲P̲R̲I̲N̲T̲E̲R̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
up TDP x x x x x
x x
down TPD x x x x x
x x
burn print x x
x
x
x
x
mode TPD x x x x x
x
set alternate delivery x x
x
x
x
x
remove alternate delivery x x x x x
x
duplicate x x
x
x
x
x
remove duplicate x x x x x
x
move print x x
x
x
x
x
P̲M̲S̲ ̲C̲O̲M̲M̲A̲N̲D̲S̲:̲
retrieve messages x
x
x
x
x
x
retrieve log x x x x
x x
halt retrieval x
x
x
x
x
x
drain x x x
halt drain x x
x
Table 4.6 Command Summary (Cont'd)
4.6.1 L̲o̲c̲a̲l̲ ̲I̲n̲i̲t̲i̲a̲l̲i̲z̲a̲t̲i̲o̲n̲ ̲S̲u̲b̲s̲y̲s̲t̲e̲m̲ ̲C̲o̲m̲m̲a̲n̲d̲s̲
These are operating system related commands which are
valid in a local scope, e.g. for controlling local
peripherals. The standard Terminal Operating System
(TOS) command suite belongs to this group. TOS is described
in the CR80 minicomputer handbook.
The commands used for initializing the NCC belongs
to this group of commands. A job file facility allows
the appropriate command sequence to be submitted as
a command file.
4.7 N̲e̲t̲w̲o̲r̲k̲ ̲M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲
The Network Management Functions are implemented on
or originated from the Network Management Host. The
NMH is a general purpose computer implemented on a
CR80 computer.
The concept of a dedicated host computer, which contains
some data identical to the two NCCs, is to make a complete
segregation of the live network with its stringent
requirement to reliability and the environment of change
and experimentation connected to development functions.
4.7.1 N̲e̲t̲w̲o̲r̲k̲ ̲M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲ ̲O̲p̲e̲r̲a̲t̲i̲o̲n̲ ̲a̲n̲d̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲s̲
The NMH contains an integrated data base with various
releases of the following individual data bases
- initialization data
- configuration tables
- inventory of all network components
- statistics
- costing and billing information (incl. customer
& trarifs)
- software load files
The long term maintenance of ACDN is performed on the
NMH. New configuration are tested and validated before
implementation, new software will be developed here
and implementation of it will be initiated here. Distribution
of Network Management functions is initiated from the
NMH.
All statistics collected throughout the ACDN will end
here, and be foundation for new ideas of future inhancement
and changes is generated at the NMH.
The interface between the NMH and the rest of ACDN
will be as simple and generalized as possible. Complete
files organized as sequential files can be transferred
to and from the NMH. No direct control of the ACDN
can be performed from the NMH. When the NMH communicates
with the two NCCs it will always be controlled by the
active NCC.
The physical connection between the NMH and the ACDN
will be a supra bus connection to a collocated node.
4.7.2 N̲M̲H̲ ̲O̲p̲e̲r̲a̲t̲o̲r̲s̲ ̲P̲o̲s̲i̲t̲i̲o̲n̲s̲
The operator positions at the NMH comprises 3 VDUs
and a line printer. To support the applications, the
NMH has a floppy disk, one disk with a fixed head portion
and one removal disk. A magnetic tape station is also
included.
The above mentioned amount of operator positions are
more or less selected arbitrarily. The flexibility
of the CR80 computer allows for future expansion.
The operator positions and the functions at the NMH
are controlled by
- password checks
- operator profile with check of allowed capabilities
Capabilities given to different operators could be
- read only or update of different subsets of the
DB
- transmit data and programs to other subsystems
- access to program load files including patching.
4.7.3 D̲i̲s̲t̲r̲i̲b̲u̲t̲i̲o̲n̲ ̲o̲f̲ ̲N̲e̲t̲w̲o̲r̲k̲ ̲M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲
The long term maintenance of the ACDN is performed
at the NMH, whereas control and monitoring of the live
ACDN is performed at the active NCC. Data and programs
are transferred from the NMH to both the NCCs, but
only after they have been validated at the NMH.
New versions of software for the nodes, FEP's the Gateway
and the EMH are also developed at the NMH and transferred
to the individual subsystems.
Some data and programs are redistributed from the active
NCC to the nodes and front-end processors.
The downline loading capabilities for data and program
between the different subsystems in ACDN is performed
in generalized fashions which permits changes to different
distribution strategies in the future.
4.7.4 O̲p̲e̲r̲a̲t̲o̲r̲ ̲C̲a̲t̲e̲g̲o̲r̲i̲e̲s̲
In a large network like ACDN where many different and
sometimes contracting point of view have to be considered,
it is vital that ACDN itself support the segregation
of different aspects.
The ACDN will differentiate between all the operator
categories by use of passwords and operator profiles
defining the capabilities allocated to the operators.
At the NMH, which is involved with long term management
of the network, the network administrators performs
their tasks; like:
- Cost and Billing
- Statistics analysis
- Network directories
- Software development
4.7.5 N̲e̲t̲w̲o̲r̲k̲ ̲M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲ ̲A̲p̲p̲l̲i̲c̲a̲t̲i̲o̲n̲s̲
Different applications are implemented at the NMH.
4.7.5.1 N̲e̲t̲w̲o̲r̲k̲ ̲D̲e̲f̲i̲n̲i̲t̲i̲o̲n̲
The definition of the total network will be organized
in a distributed database. At the NMH the database
will describe configuration, billing, statistical and
planning data. The subset of the database holding configuration
data is down line loaded to both the active and the
standby by NCC. The actual control and monitoring of
the live network will be performed by the database
residing in the active NCC.
Initial definition of the total DB will be done at
the NMH. This DB will be created before distributing
subsets of the DB to both NCCs and the EMH. Any major
changes to the network configuration will be entered
at the NMH and validated and tested before it is transferred
to the NCC.
Examples of major changes are inclusion of additional
nodes, concentrators and terminals. Also reconfiguration
like moving terminals from one concentrators to another
concentrator are considered a major change.
The DB residing in the NCCs can only be modified directly
for specific detailed information, which does not change
the optimized physical structure of the NCC DB.
Tegning ?
4.7.5.2 D̲o̲w̲n̲ ̲l̲i̲n̲e̲ ̲L̲o̲a̲d̲i̲n̲g̲
Permanent or major changes to the DB is performed at
the NMH before the different subsets are transferred
to either NCCs or EMH. The concept of downline loading
serves several purposes.
o backup duplication for survivability purposes
o protection of live configuration DB from development
DB by segregation
o rune time optimization of live configuration DB
at NCC
o development optimization of NMH DB
The total DB resides on the NMH. Backup copies can
be taken on offline disks on tape and kept at a different
geographical location to be used in case of catastrophic
disasters caused by fire, building collapse etc. The
subset of the NMH DB needed for configuration of the
live network will be downline loaded to both the active
and the standby NCC.
Part of the downline loading procedure will be to select
the necessary configuration information in a sequence
suitable for transmission and subsequent establishment
of the "run time" optimized configuration DB at the
NCC.
The subset of the NMH DB transmitted to the other hosts
will be selected and transmitted in a similar fashion.
The downline loading of subsets of the DB will use
the file transfer protocol implemented in the ACDN.
4.7.5.3 S̲t̲a̲t̲i̲s̲t̲i̲c̲s̲ ̲a̲n̲d̲ ̲B̲i̲l̲l̲i̲n̲g̲
The statistics and billing function are treated together
because they are similar.
All statistics and billing transactions will eventually
be routed to the NMH for processing. Customer names,
addresses etc. and tarif calculation rules are maintained
at the NMH.
For billing the received transactions can be sorted
in sequence of for example
- customer identification
- used host identification
- used terminal identification
- transaction type identification
- time stamp
…86…1 …02… …02… …02… …02…
and the sorted transaction information can be accumulated
and merged with customer information and charging tarif
specifications to produce invoices.
4.7.5.4 Q̲u̲e̲r̲y̲ ̲L̲a̲n̲g̲u̲a̲g̲e̲ ̲a̲n̲d̲ ̲R̲e̲p̲o̲r̲t̲ ̲G̲e̲n̲e̲r̲a̲t̲i̲o̲n̲
These functions are closely related to the Data Base
Management (ref. section III 6.11).
The query facilities are performed in an interactive
mode at CRT terminals, while the report generation
capability may be prepared at CRT terminals but is
aimed at producing display or hardcopy printout with
more detailed requirements to layouts.
Both of these capabilities will be provided to Air
Canada as part of the implementation of the ACDN. The
detailed knowledge Christian Rovsing will acquire during
implementation and the efficient development tool applied
by Christian Rovsing will enable us to provide an efficient
tool for Air Canadas subsequent maintenance and enhancement
of the system without relaxation of any flexibility.
During development Christian Rovsing will define all
record types in every file and provide module for printout
of all the record types. These modules will be combined
in a well structured fashion using modern structured
program techniques like Jacksons structuring method
(ref. section III 6.11 for further information). After
familiarization with the Jackson technique Air Canada
personnel will be able to make use of all these capabilities.
4.8 N̲e̲t̲w̲o̲r̲k̲ ̲C̲o̲n̲t̲r̲o̲l̲ ̲a̲n̲d̲ ̲S̲u̲p̲e̲r̲v̲i̲s̲i̲o̲n̲
4.8.1 N̲e̲t̲w̲o̲r̲k̲ ̲C̲o̲n̲t̲r̲o̲l̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲s̲ ̲a̲n̲d̲ ̲O̲p̲e̲r̲a̲t̲i̲o̲n̲s̲
Network supervision facilities provided by ACDN encompass
the following aspects of the network:
o transport network
o concentrator network, low speed lines and links
to other networks
o host participants
o printers and associated PMS traffic functions
o local peripheral devices
All monitoring and control functions are provided for
the NCC supervisor staff including the monitoring and
control of host based resolution. A limited subset
of functions related to printer and PMS control and
CRT/remote line access network monitoring are available
to users and field technicians.
The primary network control operations are:
o Network definition
o Network initialization
o Transport system control
o External resource control
o Conversation control
o Session control
o event handling
o online table update
o test control
o Statistics and Report Generation
o Type B traffic control
o TDP printer control
o User services
o recovery procedures
The above categories of operations are (primarily)
controlled directly from a network supervisor position,
however certain commands may be exercised locally at
a node. The location and authority level of each individual
command is defined in section 4.6.
4.8.2 N̲C̲C̲ ̲O̲p̲e̲r̲a̲t̲o̲r̲ ̲p̲o̲s̲i̲t̲i̲o̲n̲s̲
The NCC is equipped with 4 identical network supervisor
terminal positions as described in section 4.4.2. These
positions are not preassigned to any particular function
but may be used completely independent of each other
for any type of work within the scope of the supervisory
function. However, specific assignments may be defined.
For example, a particular supervisor position may be
assigned for display of timed reports, another for
reception of event notifications, and so forth.
4.8.3 D̲i̲s̲t̲r̲i̲b̲u̲t̲i̲o̲n̲ ̲o̲f̲ ̲N̲e̲t̲w̲o̲r̲k̲ ̲C̲o̲n̲t̲r̲o̲l̲
The ACDN network provides global network control and
monitoring capability centralized at the NCC.
Although the overall network control responsibility
resides with the NCC, most supervisory control functions
may be activated by a supervisor at a remote location,
i.e. a node engineering position.
However, it should be noted that the Software solution
for the proposed ACDN network lends itself for future
implementation of a true distributed network control
scheme.
A practical implementation of a distributed network
would for example facilitate control areas around each
ACDN node, which would then exercise autonomous control
over its local external resource network (lines, concentrators,
devices and hosts).
4.8.4 O̲p̲e̲r̲a̲t̲o̲r̲ ̲C̲a̲t̲e̲g̲o̲r̲i̲e̲s̲
Network control is restricted to the authority classes:
o network supervisor
o field technicians
Network supervisors are allowed to perform all control
operations. Field technicians are restricted to control
of external network resources i.e. ICC trunk lines,
ICCs and terminal devices and printers.
4.8.5 N̲e̲t̲w̲o̲r̲k̲ ̲C̲o̲n̲t̲r̲o̲l̲ ̲C̲o̲m̲m̲a̲n̲d̲ ̲a̲n̲d̲ ̲F̲u̲n̲c̲t̲i̲o̲n̲s̲
4.8.5.1 N̲e̲t̲w̲o̲r̲k̲ ̲D̲e̲f̲i̲n̲i̲t̲i̲o̲n̲
The network must be defined both globally, i.e., the
complete actual configuration, and locally to each
host.
The global ACDN definition is a hierarchy which defines
both the external resources (participants and attachment)
and the internal resources, e.g. internodal and access
links.
The definition is grouped as follows:
Transport System
nodes (node-id)
link (link-id, LTU-addr.)
Virtual circuit capacity
links (link-id)
connection
speed
transport station (TS-id)
sub-transport station (DTE-addr.)
External Resource Type
host types
line types
controller types
terminal types
line group, main type (LTU-addr.)
line, sub-type (line-id)
controller (controller-id, poll-addr.)
terminal (term-id, local addr.)
NODE Configuration (NODE-id)
channel (channel-id, channel-I/F addr.)
host (host-id)
line (line-id, LTU-addr)
host or communication controller (host-id)
external resource (resource-id)
The definition is performed on-line at the NCC or off-line
at the NMH via an application which via suitable forms,
allows the operator to fill in the necessary parameters.
The defined network configuration is stored in object
files from which they can be later loaded during initialization,
recovery or dynamic reconfiguration.
Commands:
DEFINE ̲NET (in-definition-file)
(out-definition-file)
This command starts the network definition application
which via a menu, selects the forms to be filled in
or changed.
If in-definition-file is specified, an existing definition
is used as starting point.
Out-definition-file is, if specified, used to store
the new definition.
Apart from the form editing facilities, DEFINE-NET
is able to merge and split definition files. It also
contains a print utility for easy and legible forms
print out.
The definition of the networks seen by the hosts are
done at the hosts. These definitions must use the same
names as ACDN to identify each external resources.
To allow ACDN to perform address translation between
ACDN and host network addresses, a resource name-address
table must be existing prior to network initialization.
4.8.5.2 N̲e̲t̲w̲o̲r̲k̲ ̲I̲n̲i̲t̲i̲a̲l̲i̲z̲a̲t̲i̲o̲n̲
The entire network is initialized through three phases:
o NCC System initialization
o Transport System initialization
o External Resources initialization
At the successful end of the first phase, the NCC is
able to start remote initialization of all network
computers. After this second phase, the standard network
is ready to provide transport services.
When phase three is finished, the entire network is
ready to accept end user requests.
Note that there may be a fourth phase, namely the pseudo
initialization performed by each host access network
to synchronize the individual host network appearence
with ACDN.
N̲C̲C̲ ̲S̲y̲s̲t̲e̲m̲ ̲I̲n̲i̲t̲i̲a̲l̲i̲z̲a̲t̲i̲o̲n̲
The NCC is bootloaded from the system file on the connected
disc. When this is terminated, the Terminal Operating
System (TOS) is activated, using the system console
as TOS master console.
The operator terminals are now assigned to TOS and
the File Management System (FMS) is initialized by
standard TOS commands.
The permanent NCC programs are loaded via TOS and the
designated master operator terminal can now accept
operator logon and further network initialization commands.
At this stage the NCC is in offline mode of operation.
The NCC may be in one of three states:
o offline
o standby
o active
These states and the associated commands are further
described in section 4.14.
To change the state of the NCC the following commands
are available.
Commands:
OFFLINE
The state of the NCC is changed from standby to offline.
STANDBY
The NCC enters the standby mode from the offline mode.
ACTIVE
The NCC status is changed to active, where if assumes
full operational control of ACDN.
T̲r̲a̲n̲s̲p̲o̲r̲t̲ ̲S̲y̲s̲t̲e̲m̲ ̲I̲n̲i̲t̲i̲a̲l̲i̲z̲a̲t̲i̲o̲n̲
Nodes may be loaded and initialised from the NCC when
they are connected via an operable link either to NCC
or to a node which already part of the network.
Normally, however, they are bootloaded from the system
file on the locally connected disc, i.e. the disc of
the Nodal Control Processor. The initialization is
completed when the node is included in the packet sub
network and the control conversations are set up.
LOAD node-id program-file
This command loads a node computer which is in its
basic state with the complete system found in program-file.
INCLUDE node-id configuration-file
This command initialises the links, virtual circuits
and transport stations in the node, as defined in the
transport system configuration-file. This causes the
node to become part of the network.
EXCLUDE node-id
This command removes the node from the network (if
it was already included) and forces the node computer
into a passive basic state from which it can be remotely
dumped or loaded.
The external resource defined in the local network
configuration can be included when the node has been
initialised. This is done based on the definition file
which states which external resources are to be initially
included.
INCLUDE EXTERNAL node-id node-configuration-file
This command will transfer the node-configuration-file
information to the node, thus causing the node to perform
inclusion of all resources in its local network which
are defined to be included.
Excluded defined resources may be included later via
a configuration command.
A message is displayed on terminals to indicate that
ACDN is ready.
Input from hosts is enabled, but in the case of an
IBM VTAM host, it is the responsibility of the VTAM
operator to initiate traffic by starting VTAM.
4.8.5.3 T̲r̲a̲n̲s̲p̲o̲r̲t̲ ̲S̲y̲s̲t̲e̲m̲ ̲C̲o̲n̲t̲r̲o̲l̲
Transport system control manages the physical resources
which are available to support conversations, in other
words, the links and the packet switching part of the
nodes.
The main functions are:
- Link management
- Virtual Circuit management
- Resource Utilization control
These functions are mainly available to the operator
to correct errors and to tune the network. Under normal
operation, the functions are performed automatically
by other parts of the system.
4.8.5.3.1 L̲i̲n̲k̲ ̲M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲
Each link in the network can be managed individually
through NCC operator commands.
Links which are not directly connected to the NCC are
managed via a node which is directly connected to the
link. For this to be possible that node must be included
in the network and have its control conversations with
the NCC open.
INCLUDE-LINK Link-id (parameters)
This command causes a level 2 link connect to be issued
by the Link protocol for the designated link. If the
connection is successful, the link is then included
in the routing calculation.
EXCLUDE-LINK Link-id
This command causes a level 2 disconnect to be issued
by the Link protocol for the designated link. Then
the link is excluded from the routing calculation.
A link must be excluded before any link tests or remote
dump or load operations can be performed on that link.
LINK-STATUS node-id link-id
This command displays the definition and status of
one link or all links on a node.
4.8.5.3.2 V̲i̲r̲t̲u̲a̲l̲ ̲C̲i̲r̲c̲u̲i̲t̲ ̲M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲
c̲o̲m̲m̲a̲n̲d̲s̲
INITIATE-VC source-addr dest-addr.
Normally, virtual circuits are not set up manually,
but the operator may choose to do so either to test
the set-up procedure, or to increase the resources
for certain connections. Source-addr and dest-addr
are two subscribers of the packet subnetwork.
TERMINATE-VC node-id channel-id
Removes a virtual circuit on the designated node.VC-clear
is then automatically propagated to the two subscribers
of the VC. This function is used mainly to clean up
in cases where a virtual circuit has not been properly
cleared by the system itself.
VC-STATUS node-id channel-id
This command obtains the virtual circuit parameters
(PVC or VC, next-channel-id window size, max-conv.)
and the status of the VC (internal-state, number of
open conversations, number-of-packets-on-output-queue,
traffic-volume).
A complete virtual circuit may be traced from source
to destination through successive use of this command.
4.8.5.3.3 R̲e̲s̲o̲u̲r̲c̲e̲ ̲U̲t̲i̲l̲i̲s̲a̲t̲i̲o̲n̲ ̲C̲o̲n̲t̲r̲o̲l̲
This control is performed by parameter setting at various
levels. Some of the parameters are determined by the
users, others at system generation time, and others
by the network definition or network operator. The
parameters are divided into three major groups:
1) Conversation parameters
2) Network parameters
3) Routing algorithm
1) C̲o̲n̲v̲e̲r̲s̲a̲t̲i̲o̲n̲ ̲p̲a̲r̲a̲m̲e̲t̲e̲r̲s̲
These parameters are affecting the user of the conversation
directly. The parameters which can be changed are:
o maximum message length
o number of packets in transit.
2a) S̲t̲a̲t̲i̲c̲ ̲N̲e̲t̲w̲o̲r̲k̲P̲a̲r̲a̲m̲e̲t̲e̲r̲s̲
During initialisation of the network, certain parameters
are set which are valid during all network operations
until the network is closed down. The parameters to
be changed are:
o maximum frame size
o maximum packet size
2b) D̲y̲n̲a̲m̲i̲c̲ ̲N̲e̲t̲w̲o̲r̲k̲ ̲P̲a̲r̲a̲m̲e̲t̲e̲r̲s̲
These parameters are set at network definition time,
but may be changed by the network operator during normal
operation:
o time-out value when waiting for acknowledge
o number of retries on links
o threshold values for: trunk delay
buffer occupancy
VC-multiplexing
Commands:
INCLUDE-LINK Link-id (parameters)
When a link is initiated, the default parameters are
taken from the network definition, but they may be
specified:
o time-out value
o number of retries
o maximum trunk delay
If during operation, the specified values are exceeded,
an event is generated to the NCC.
BUFFER-LIMIT (new limit values)
If no new-limit-values are given, this command displays
the current limits and the current utilisation. Otherwise,
the new limit is set. If the utilisation exceeds the
limit-2, an event is generated and no further traffic
is assigned to use that resource until the utilisation
has fallen below limit-1.
VC-MUX node-id channel-id max-conv
This command controls the number of independent conversations
(max-conv) which may be established for a given virtual
circuit.
3) R̲o̲u̲t̲i̲n̲g̲ ̲A̲l̲g̲o̲r̲i̲t̲h̲m̲
A certain strategy has to be decided upon, on how to
change the routing. Several factors must be taken into
account, such as:
o topology
o trunk speeds
o load on nodes and trunks
o traffic type
These factors are being used with different weight
factors by the routing algorithm.
The time elapsed between two routing updates is another
factor which has to be part of the routing strategy.
Commands:
ROUTING node-id
This command displays either the complete routing table
in the NCC or the specific routing table for a single
node.
The table shows for (link, destination)-pair, the cost
induced by using that particular link to reach the
destination.
4.8.5.4 E̲x̲t̲e̲r̲n̲a̲l̲ ̲R̲e̲s̲o̲u̲r̲c̲e̲ ̲M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲
The management of external resources is controlled
by
the network operator at the active NCC. All permanent
error situations generate events in the NCC that should
be acknowledged by the operator, and lead to a corrective
action. If the error cannot readily be resolved, the
resource in error should be excluded from the network
to isolate it from any side effects caused by the erroneous
resource and to allow thorough fault investigation
through test facilities.
Control of the resources is done according to the hierarchy
used for the network definition, i.e.
o Local network
o Line group
o Line
o Controller
o Terminal
Each resource has two state variables:
o included/excluded
o operable/in-error
and resources capable of being in session have one
more state variable:
o free/in-session
The external resource management functions can be used
to bring a resource into a known state.
When the system is initialised or later, when it is
running, new resources can be made known to the system.
Whether they are included at the same time depends
on the specification in the definition file.
Likewise, when a resource is excluded from the network,
it can be specified that it be completely deleted and
thus made unknown.
Commands:
INCLUDE node-id …0e…node-configuration-file…0f…
resource-id
If the first alternative is used, the resource is both
defined to ACDN and, if it is defined to be initially
included, then this is also done.
In the latter case, the resource is unconditionally
included.
Included resources are put in their initial state,
which is:
included, operable, and free.
Inclusion of resources require synchronization with
the host access method. Note that if the resource is
not defined to the host, a dynamic reconfiguration
must be performed in the host access method,before
the resource can be accessed by the host.
EXCLUDE resource-id DELETE
This command excludes the named resource (and all depending
resources) from normal use. If the resource is in
session, the session is abnormally terminated. If the
DELETE option is specified, the resource is made unknown
to ACDN. This function requires synchronization
with the host access method.
4.8.5.4.1 I̲C̲C̲ ̲C̲o̲n̲t̲r̲o̲l̲ ̲C̲o̲m̲m̲a̲n̲d̲s̲
The ICC status control commands after the status of
various ICC network components. The purpose of this
group of commands is to manipulate ICC lines, control
the ICC's, RLMC's and LPMC mode of operation.
Further, commands for regulation of type B message
traffic are provided.
Type B traffic can be controlled by both input regulation
and delivery control. SKIP/POLL commands control input
traffic and delivery control and HOLD/RELEASE commands
control delivery of output traffic.
HOLD/RELEASE commands are used to control the delivery
of messages to a terminal or line. HOLD stops traffic
and RELEASE allows traffic to flow.
Commands:
INCLUDE-LINE node-id line-id
Marks the indicated ICC line up, and allows normal
communications procedures to resume on this line. If
the line is a dial-up line, a manual dial-up connection
must be made prior to issuing this command.
EXCLUDE-LINE node-id line-id
Marks the indicated ICC trunk down, and stops all traffic
on this line.
SKIP-LINE node-id line-id
Inhibits polling of the specified line
POLL-LINE node-id line-id
Causes polling of the specified line to be resumed.
HOLD-TRAFFIC node-id line-id
Marks the specified line in hold condition. Traffic
in queue for the line will not be transmitted.
RELEASE-TRAFFIC node-id line-id
Clears a traffic hold condition and resumes queued
traffic to flow for the specified line.
STATUS-LINE node-id line id
Produces a status display showing all relevant status
for the specified line.
INCLUDE-ICC node-id ICC-id
Marks the indicated ICC up, and allows the resumption
of normal communications procedures on all trunks associated
with this ICC.
EXCLUDE-ICC node-id ICC-id
Marks the indicated ICC down, and stops all activity
to and from this ICC.
SKIP-ICC node-id ICC-id
Initiates polling of the specified ICC
POLL-ICC node-id ICC-id
Causes polling of the specified ICC to be resumed.
HOLD-TRAFFIC node-id ICC-id
Marks the specified ICC in hold condition. Traffic
in queue for this ICC will not be transmitted.
RELEASE-TRAFFIC node-id ICC-id
Clears a hold condition and resumes queued traffic
for the specified ICC.
STATUS-ICC node-id ICC-id
Produces a status display showing all relevant status
for the specified ICC.
BACKUP-ICC node-id ICC-id
Initiates a control message to the sister ICC of the
ICC specified in the command, directing the sister
ICC to assume all traffic for the specified ICC.
NORMAL-ICC node-id ICC-id
Initiates a control message to the sister ICC of the
specified ICC, directing it to resume normal mode of
operation, with each ICC handling its own traffic load.
BACKUP-RLMC node-id ICC-id RLMC-id
Initiates a control message to the sister ICC of the
specified ICC, directing it to assume all traffic for
the specified RLMC.
NORMAL-RLMC node-id ICC-id RLMC-id
Initiates a control message to the sister ICC of the
specified ICC, directing it to resume normal mode of
operation for the specified RLMC.
RESET-ICC node-id ICC-id
Sends a reset control message to the specified ICC
to re-initialize the ICC program.
UP-ICCCPU node-id ICC-node line-id
Marks the CPU controller on the specified ICC connected
to the specified line, as up.
DOWN-ICCCPU node-id ICC-id line-id
Marks the CPU controller on the specified ICC connected
to the specified line as down, and stops all activity
over this line to this ICC.
4.8.5.4.2 D̲e̲v̲i̲c̲e̲ ̲C̲o̲n̲t̲r̲o̲l̲ ̲C̲o̲m̲m̲a̲n̲d̲s̲
The Device control commands alter the status of various
types of user terminals and printers attached to the
ACDN network.
Type B traffic regulation capability is provided through
skip/poll and hold/release commands.
Commands:
INCLUDE-TERM node-id ICC-id term-id (parameters)
The specified User terminal is included in the network
configuration
EXCLUDE-TERM node-id term-id
The specified terminal is excluded from the network
configuration
SKIP-TERM node-id term-id
Inhibits polling of the specified terminal.
POLL-TERM node-id term-id
Causes polling of the specified terminal to be resumed.
HOLD-TRAFFIC node-id term-id
Marks the specified terminal in hold condition. Traffic
in queue for the terminal will not be transmitted.
RELEASE-TRAFFIC node-id term-id
Clears a traffic hold condition and resumes queued
traffic to flow for the specified terminal.
STATUS-TERM node-id term-id
Produces a status display showing all relevant status
for the specified terminal.
This command function may be used for displaying the
connection status of all the various types of ACDN
devices, CRT's, printers and FIDS, etc. The status
indication will include, but is not limited to, the
following:
o sign-in status (free, in session)
o terminal condition status (included/excluded,
operable/in error)
o status of physical and logical paths to destination
(multiplexer, remote lines, concentrator including
concentrator components, concentrator lines, nodes
and node components, inter nodal trunks)
o routing status - primary or alternate routing on
access network, routing through backbone network
to host/application.
These status indications will be available to network
supervisor and technicians accessing the network from
an NCC supervisor or engineering position, or from
an ordinary user terminal attachment. The status information
will be retrieved from the global NCC device status
tables, which are recoverable in the event of NCC failure.
4.8.5.4.3 S̲y̲n̲c̲h̲r̲o̲n̲i̲s̲a̲t̲i̲o̲n̲ ̲o̲f̲ ̲n̲e̲t̲w̲o̲r̲k̲ ̲a̲p̲p̲e̲a̲r̲e̲n̲c̲e̲s̲
In principle the external resource management described
in the previous section also includes management of
participants.
However, since the control protocols between ACDN and
participants are a mixture of peer-to-peer protocols
and master-slave protocols reflecting the shared management
responsibility, it is appropriate to describe participant
management in a separate section.
The control is performed according to the hierarchy
used in the definition of a Host Interface Processor
(HIP), i.e.:
o HIP
o Channel or link connection
o Host
o Application
As described in section 4.8.5.4 the ADD, DELETE, INCLUDE
and EXCLUDE commands operates on these resources according
to the hierarchy, and maintain for each defined resource
two state variables:
o Included/Excluded
o Operable/In-error
However, since ACDN does not manage the participants
themselves, but only their access to ACDN, some independent
control operations must be performed at each host.
The management of applications can be given a general
host independent interpretation.
The services provided to the users in the combination
of the services provided by the NCC itself and the
applications in the hosts to which the user may connect.
Consequently through the manipulation of the state
of applications as perceived by ACDN the NCC provides
centralized control of which applications may be currently
accessed and ih which host they should be accessed.
The state of all included applications is regularly
polled to enable the NCC to respond automatically to
any asynchronous application state change. On request
the current state of all applications is available
to the users from the NCC.
Since the management of the hosts is dependent on the
host type a separate description for IBM and Univac
is given in the following sections.
4.8.5.4.3.1 M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲ ̲o̲f̲ ̲I̲B̲M̲ ̲h̲o̲s̲t̲s̲
The NCC operator controls the IBM host access to ACDN
in coordination with the VTAM operator. This is because
the basic protocol is a master/slave protocol with
the IBM host as the master, thus inhibiting ACDN to
initiate the communication.
The channel interface or the secondary SDLC link station
in the HIP is enabled/disabled through the use of include/exclude
commands. When this level is included the basic communication
may start, but the activation request issued for the
HIP by the IBM host is not responded until also the
host is included.
The INCLUDE host ̲id command readies the HIP to accept
an ACTPU request. However, the include is kept pending
until the VTAM operator has initiated the activation.
When the HIP receives the ACTPU request it responds
positively and also responds to the INCLUDE command.
When the host is successfully included a session is
established between the NCC and the Cross Domain Resource
Manager (CDRM) in the host. When this is successfully
done, the host is marked in-session.
As long as the host is included, operable and in session
all synchronization with the host is done on this CDRM
session. This also includes regular monitoring of the
status of all application logical units which are defined
to reside in the host.
The NCC operator can exclude a given host from ACDN
via the EXCLUDE host ̲id command. If the host is still
marked in-session, the CDRM session is orderly terminated,
causing all other sessions with applications in that
host to be terminated.
When the CDRM has been terminated the EXCLUDE command
is forwarded to the HIP causing it to respond negatively
to all host requests except a close-down (DACTPU).
The NCC Is synchronized with the IBM host via the CDRM
session. In addition, however, the HIP monitors the
host interface and reports asynchronously any inoperative
condition (e.g. a timeout on the channel interface
or reception of a DACTPU for the HIP when the host
is still included). If the host becomes inoperative,
the NCC will terminate all sessions with that host
and report the loss of the host to all other IBM hosts.
4.8.5.4.3.2 M̲a̲n̲a̲g̲e̲m̲e̲n̲t̲ ̲o̲f̲ ̲t̲h̲e̲ ̲U̲N̲I̲V̲A̲C̲ ̲1̲1̲0̲0̲ ̲H̲o̲s̲t̲
The NCC operator controls the UNIVAC 1100 host access
to ACDN in coordination with the CMS 1100 operator.
No operator intervention is normally needed. But as
the character of the protocol on the channel interface
is initialized from the host, the operator on the host-site
will have to restart the channel if the ACDN is not
in operation when the host is booted.
The channel interface in the HIP is enabled/disabled
through the use of include/exclude commands. When the
command is included and working, the basic communication
may start. The basic communication is based upon the
logical port sessions taken care of by the PFC-level
(Port Flow Control). These logical port sessions will
be included as they are required by a user terminal
or batch station by means of a CONNECT-command.
Initially, by means of a Host-INCLUDE-command, an NMS
(Network Management System) logical port session is
established to take care of supervisory functions.
The NCC operator may exclude any UNIVAC 1100 host from
the ACDN issuing the host-EXCLUDE-command. If the host
is marked "in-session", all system sessions and logical
port sessions will be terminated gracefully, including
the above mentioned NMS-logical port session.
4.8.5.5 C̲o̲n̲v̲e̲r̲s̲a̲t̲i̲o̲n̲ ̲C̲o̲n̲t̲r̲o̲l̲
Conversations are the highest level standard protocol
used in ACDN. Therefore, (and since there is always
a one to one correspondance between sessions and conversations)
the control of conversations permit the most detailed
and comprehensive resource control within ACDN.
The conversation is re-established in case of network
failures which do not involve the two transport stations
which are connected via the conversation. This allows
the conversation to resume without loss of data when
alternative network resources have been assigned to
it.
In this case, the session using the conversation is
not aware of the temporary suspension of the conversation.
Conversations are uniquely identified by their two
CAP-id's which permit global identification both of
the conversation itself and its data units.
Commands:
CONVERSATION TS ̲id VC-id type state
resource-id
This command allows either a global status overview
(no parameter specified) giving for each transport
station, the number of conversations of each type
(control, transparent, interactive, batch, measurements)
and one of the restrictions is specified, all conversations,
satisfying the restriction will be displayed with:
o conversation-id
o corresponding session-id
o maximum resource claim
o current resource utilisation.
INTERRUPT conv-id
This command suspends the conversation without loss
of data. This may be done to allow examination of
the conversation in a steady state or to allow change
of the maximum resource claim for the conversation.
conv-id
ALL
RESUME TS-id type state resource-change
VC-id
resource-id
This command resumes one or more suspended conversation
which satisfies the selection criteria given in the
first line.
If the resource-change is specified, then the conversations
will continue with the new set of resource requirements.
The credit value and the conversation class can be
changed.
conv-id
TERMINATE TS-id
VC-id type state
resource-id
This command terminates the selected conversations
and corresponding sessions.
4.8.5.6 S̲e̲s̲s̲i̲o̲n̲ ̲C̲o̲n̲t̲r̲o̲l
Since several different types of sessions may exist
within ACDN, and since these sessions may be partly
controlled by the participants, the session control
in ACDN is only used at a level n,eded to synchronize
with the participants and to provide certain end user
functions. There is one exception, however, the session
limit is used as a convenient tool for a gross resource
control.
Commands:
user-id-1 appl-id-2
INITIATE-SESSION user-id-2
term-id-1 term-id-2
This command initiates establishment of a session between
an attachment, either identified by the user-id-1,
or the term-id-1, and a participant application or
another attachment.
The session is not established until id-2 acknowledges
the session initiation.
Otherwise the selected sessions are displayed with
end-user identification (appl-id, term-id and user-id
and corresponding conv-id.
The state may be : in-session or session-pending (which
indicated a session being established).
SESSION-LIMIT node-id (limit)
This command displays or sets the maximum number of
sessions allowed in a given node. A decrease of the
limit will not cause sessions to be terminated.
4.8.6 A̲l̲a̲r̲m̲s̲ ̲a̲n̲d̲ ̲E̲v̲e̲n̲t̲ ̲H̲a̲n̲d̲l̲i̲n̲g̲
4.8.6.1 E̲v̲e̲n̲t̲s̲
Events occuring in various parts of ACDN cause event
messages to be forwarded to the NCC for the information
of the network supervisor.
Events are described as follows:
o alarms (most serious)
o alerts
o notices
All events received at the NCC are saved in a disk
resident list of active events. Once an event has been
included in the list a positive operator acknowledge
is required for the event to be removed.
Errors are detected by software entities located in
the hosts, in the NCC and in the node. The following
list mentions some of the failures which are detected
- internal NCC failure (alarm)
- node failure (alarm)
- trunk failure (alarm)
- host failure (alarm)
- terminal failure (alarm)
- irrecoverable protocol errors (alarm)
- ICC trunk line open failed (alarm)
- ICC CPMC not responding (alarm)
Software entities are being provided in order to determine
when a threshold has been reached. The list of thresholds
which are detected include
- Node buffer low (alert)
- EMH buffer low (alert)
- trunk queues too long (alert)
- trunk line high error rate (alert)
Other events which will be reported to the event and
alarm handling includes:
- ICC automatically downed (alert)
- ICC backed up by sister ICC (alert)
- RLMC backed up (alert)
- intermittent terminal failures (notice)
- recoverable protocol errors (notice)
4.8.6.2 P̲r̲e̲s̲e̲n̲t̲a̲t̲i̲o̲n̲
All events are presented at the NCC. They contain time
stamp, event-type, resource name, and event message.
Event notification is done at all operator consoles
which have that particular event type assigned.
All events must be acknowledged by the operator acknowledge
facility, or through use of the SCAN-EVENTS command.
Whenever an event is received it is immediately written
to the log file. The log file may be printed, either
in an off-line mode, or on-line. In on-line mode each
event is printed as soon as it has been written to
the log file.
The log file may also be displayed on the console to
allow an interactive search for "interesting" events.
Commands:
SCAN-EVENTS
This command lists all unacknowledged events and allows
the operator to acknowledge groups of events based
on time stamp, event type or resource name.
PRINT-LOG ON
OFF
RESUME
This application controls the print out of the event
log, RESUME causes print out to resume from the position
in the log file where it was last stopped. ON enables
the print out starting from the next incoming event.
OFF disables the print out and frees the printer.
BROWSE-LOG log-file
This application provides search and display facilities
on the contents of the current log-file (or another
log-file if a file is specified).
Commands to browse-log provide selection and display
of events based on the following criteria:
o time interval
o event type
o resource name
or a combination thereof.
4.8.6.3 A̲c̲t̲i̲o̲n̲s̲ ̲t̲o̲ ̲b̲e̲ ̲t̲a̲k̲e̲n̲ ̲d̲u̲e̲ ̲t̲o̲ ̲E̲v̲e̲n̲t̲ ̲o̲c̲c̲u̲r̲a̲n̲c̲e̲
Event messages may require some action to be taken.
Action is taken by an automatically initialized program
in the NCC or by an operator intervention. Counters
placed in the nodes in order to detect thresholds are
reset automatically by the generation of the event.
4.8.7 O̲n̲l̲i̲n̲e̲ ̲t̲a̲b̲l̲e̲ ̲u̲p̲d̲a̲t̲e̲
The NCC controls a set of files which are being created
at system start up time or during the operation of
the network.
The files contain:
o Network Definition Tables
o User Profile
o Terminal Profiles
o Operator Profiles
o Statistics Data
o Accounting Data
o Trace Data
o Log Data
Network Definition Tables keep a list of all host application
programs, NCC application programs to which a network
user may log on, terminals, nodes etc.
User Profiles File contains the user profile for all
authorized ACDN users and additional information related
to the user. The file keeps data link user-id, password,
terminal-id list, expiration date, messages waiting
indicator etc. The password may be changed by the
user, but not during conversation with a host.
The user profile may contain an expiration date. After
this date it can no longer be used to access ACDN.
However, it remains in the user profile data set until
explicitly deleted.
Operator Profiles File contains the operators profile.
Since this file from a security point of view is the
most sensitive access is restricted to one application
program which requires a special capability to be called.
Terminal Profiles File contains all information of
terminals included in ACDN. Subsets of each terminal
profile may be online updated.
This Application Program implements its own third level
password which should be regarded as the master password
of the system. Note, however, that knowledge of this
password alone is not enough to break the system; one
must also have the capability to be asked for it.
Via this application program the system administrator
is able to edit each entry in the operator profile
file.
Statistics Data File collects the statistics received
when conversations are established and when they are
taken down. During operation data are collected about
errors, retries etc.
Accounting Data File contains information about all
conversations which have taken place. Information messages
exchanged, the user involved, the application program
involved is stored.
This data may be used in a billing system.
Trace Data File contains a "snapshot" or record of
data. As the information passes a certain point the
ACDN a trace record is made during a conversation.
Traces may be performed on lines, buffers etc.
The Logfile keeps data collected during operation:
If a user tries to log on to the system and the request
is rejected information is kept in the Log file. Errors
discovered and recovered from during operation are
logged. Messages sent from or to the NCC are being
logged.
Information for failing hosts, restarted hosts. The
information kept about incidents like the above mentioned
consists of a time stamp and a short message in order
to determine the sort of incident which has happened
during operation.
The NCC operator is provided with a set of tools in
order to control these files.
A texteditor to do normal editing operations on files
is provided.
Three files are particularly protected against unauthorized
access:
o Network Definition Tables
o Operator Profiles File
o User Profiles
These files are maintained under control of a set of
application programs which can be invoked by the operator
during normal operation.
The file system supports normal password protection
on these files.
The file system provides normal operations like create
file, delete files protected with a password a,e not
changed by any of the above-mentioned operations if
the correct password is not specified.
Files which are not essential are not provided with
any protection, but back-up copies of files should
be kept at all times.
The NCC provides an application program to transfer
files from the NCC to the host. This facility may
be used to transfer statistics file or accounting file
for further processing by the host.
4.8.8 T̲e̲s̲t̲ ̲C̲o̲n̲t̲r̲o̲l̲
Testing functions available to network supervisors
and technicians includes:
o Reading of remote computer memory
o Dumping remote conputer memory
o Various levels of line loop tests according to
V54 specifications
These test functions may be activated at the NCC or
locally at a node work position. These functions are
further described in section 4.13.1.1
4.8.9 S̲t̲a̲t̲i̲s̲t̲i̲c̲s̲ ̲a̲n̲d̲ ̲r̲e̲p̲o̲r̲t̲ ̲g̲e̲n̲e̲r̲a̲t̲i̲o̲n̲
This section describes thew command functions available
for controlling statistics collection and report generation.
Details about these subjects are given in section 4.11.
4.8.9.1 S̲t̲a̲t̲i̲c̲s̲t̲i̲c̲s̲ ̲C̲o̲m̲m̲a̲n̲d̲s̲
Statistics collection in the ACDN network can be globally
controlled from the NCC. The following command functons
are available:
Commands:
STATISTICS-FILE stat-file
This command sets (or displays the name of) the file
used for the permanently collected statistics. This
command must be issued as part of the NCC initialization
and may be later re-issued to change to another file.
PRINT-STATISTICS stat-file resource-type
resource-address
This command prints in readable form selected entries
from stat-file (default is the current permanent statistics
file). The selection may be on either resource type
or resource address.
Each entry is printed on one line.
term-id
START/STOP- STATISTICS ctlr-id stat-file
line-id time-interval
These commands start/stop collection of extended statistics
for a designated resource.
The default for time-interval is infinite. Otherwise
the statistics recording stops after time-interval
has expired.
The NCC holds data about each conversation in the system.
Each entry in the account file describes one conversation.
In an account file is stored at log on user-id (or
term-id if user-id is not present), log on message,
time stamp. At log off, the user-id and the time stamp
are stored.
The WRAP-UP response (part of conversation protocol)
includes statistical data which contains the number
of messages exchanged during the conversation. The
number of messages will be stored into the account
file entry.
Command:
ACCOUNT-FILE acc-file
This command sets (or displays the name of) the account
file to be used. This command must be issued at NCC
initialisation time and may later be reissued to switch
to another file.
4.8.9.2 R̲e̲p̲o̲r̲t̲ ̲G̲e̲n̲e̲r̲a̲t̲i̲o̲n̲ ̲C̲o̲m̲m̲a̲n̲d̲s̲
Reports available to operational staff upon request
includes the following:
o Response Time Report
o System Queue Report
The contents of these reports are further described
in section 4.11.
Commands:
RESPONSE-TIME term-id
Generates a report of CRT response times within pre-determined
parameters. The report identifies the terminal, the
number of responses within each timing category, the
number of time-outs, and the total number of transactions
entered.
QUEUE line-id/term-id
Generated a report of all undelivered protected traffic
queues (type B) to specific printer addresses. The
report identifies the network, the line, the printer
terminal, the message priorities, and queue totals
for each address. Delivery of this report is to a network
supervisor position printer.
4.8.10 T̲y̲p̲e̲ ̲B̲ ̲t̲r̲a̲f̲f̲i̲c̲ ̲c̲o̲n̲t̲r̲o̲l̲
This section describes the command functions available
for controlling TDP printers and type B traffic delivery.
The functions are further described in section 4.9
(EMH). These functions are also available for users
(section 4.12).
4.8.10.1 T̲D̲P̲ ̲P̲r̲i̲n̲t̲e̲r̲ ̲C̲o̲m̲m̲a̲n̲d̲s̲
For management of the TDP printers at remote locations
the following commands are availale:
Commands:
UP-TDP term-id
Marks the indicated TDP printer as up. May originate
from an outstation.
DOWN-TDP term-id
Marks the indicated TDP printer as down, and stops
traffic activity to this printer after any current
message in progress has completed. May originate from
an outstation.
MODE-TDP
Places the TDP printer physically attached to the terminal
originating this command in TDP (transfer-direct-to-printer)
mode. An "ACK" message is displayed on the terminal's
CRT screen.
MODE-TSL
Places the printer physically attached to the terminal
originating this command in TSL (Transfer Screen Locally)
mode after any TDP message in progress has been completed.
BURN term-id
Burns (discards) the TDP message currently being delivered
to the specified printer. If no message is currently
being delivered, the message with the highest priority
in queue is burned. This command allows the operator
to eliminate from the system a badly-constructed message
that cannot be accepted by a given TDP printer.
4.8.10.2 T̲Y̲p̲e̲ ̲B̲ ̲T̲r̲a̲f̲f̲i̲c̲ ̲d̲e̲l̲i̲v̲e̲r̲y̲ ̲C̲o̲n̲t̲r̲o̲l̲
In the event of a type B traffic delivery problem,
confined to a terminal, certain commands are available
to alternate deliver or duplicate deliver the traffic
to another printer. The commands are further described
in section 4.9 (EMH)
Commands:
SET-ALT-DEL term-id…0f…1…0e… p term-id…0f…2…0e…
Routes all the traffic of priority p queued to and
destined for terminal 1 to a specified alternate terminal
2.
REM-ALT-DEL term-id p
Removes the specified terminal from alternate routing
and returns it to normal delivery status. New messages
of priority p are once again delivered directly to
this terminal.
SET-DUP-DEL term-id…0f…1…0e… p term-id…0f…2…0e…
Duplicates all messages of priority p delivered to
terminal 1 at terminal 2. Duplication will continue
until changed by a remove command.
REM-DUP-DEL term-id…0f…1…0e… p
Stops duplicate delivery of priority p messages being
delivered to terminal.
MOVE term-id…0f…1…0e… p term-id…0f…2…0e… N
Moves N (maximum 50) priority p messages currently
queued to terminal 1 to terminal 2.
4.8.11 U̲s̲e̲r̲ ̲S̲e̲r̲v̲i̲c̲e̲s̲
The network supervisor has at his disposal the following
user service functions:
o Sign-in message
o Broadcast message
4.8.11.1 S̲i̲g̲n̲-̲i̲n̲ ̲m̲e̲s̲s̲a̲g̲e̲s̲
The sign-in message function allows the operator to
define an information message to be displayed to a
user when he logs on to the network service.
Commands:
SIGN-IN-MESSAGE text
The command allows one text line to be stored and output
on all devices which support this when they perform
logon to ACDN.
If no text is specified, the message currently output
during logon is displayed.
4.8.11.2 B̲r̲o̲a̲d̲c̲a̲s̲t̲ ̲M̲e̲s̲s̲a̲g̲e̲ ̲F̲a̲c̲i̲l̲i̲t̲y̲
The broadcast message command allows a message of up
to 22 lines to be sent to a specified CRT, to a range
or all CRT sets and/or all teletype terminals. Broadcast
messages are used when all or certain locations must
be advised of a planned function or system shutdown,
local operating conditions, etc.
The message remains active in the system for the time
specified, or until it has been delivered to all the
desired terminals. For a terminal which has a broadcast
message outstanding, an info-indication is appended
to all output to the terminal, prompting the user to
solicit the broadcast message is solicited and sent
to the terminal. To solicit the message the user depresses
the ENTER key on the CRT.
A CRT can solicit a given broadcast message only once,
and therefore the info-indicator is not appended once
the broadcast message has been delivered to the terminal.
Broadcast messages to teletype terminals are sent as
normal teletype messages. These teletype messages will
be created and processed as normal protected traffic.
Broadcast messages can be sent to the various terminal
categories indicated in the following list:
Commands:
BROADCAST time ALL
A message is sent to all CRTs. Time is the number of
minutes the message is to remain active in system.
A message is ready to be transmitted to every configured
CRT on the network.
BROADCAST time Nxxxxxxx…0f…1…0e… Nxxxxxx…0f…2…0e…
A message is sent to a range of CRTs. N = Network xxxxxx…0f…1,2…0e…
are the logical id's of the first and last terminal
within the range. A message is ready to be transmitted
to the terminals identified by the id range.
BROADCAST time Nxxxxxx
A message is sent to a specific CRT. Only the terminal
named in the command may solicit the message.
BROADCAST time all TTY
A message is sent to all CRTs and to all Teletype Terminals
BROADCAST time TTY
A message is sent only to all Teletype Terminals
BROADCAST time APP (RES, DRV, PMS or VIA)
A message is sent to all terminals signed in to a specific
Host/application.
4.9 E̲l̲e̲c̲t̲r̲o̲n̲i̲c̲ ̲M̲a̲i̲l̲ ̲H̲o̲s̲t̲ ̲O̲p̲e̲r̲a̲t̲i̲o̲n̲s̲
4.9.1 E̲l̲e̲c̲t̲r̲o̲n̲i̲c̲ ̲M̲a̲i̲l̲ ̲H̲o̲s̲t̲ ̲O̲p̲e̲r̲a̲t̲i̲o̲n̲s̲ ̲a̲n̲d̲ ̲I̲n̲t̲e̲r̲f̲a̲c̲e̲s̲
The services offered by the EMH are the following:
o Direct delivery traffic handling (TDP-TYPE B)
o Protected message switching (PMS-TYPE B)
o Supervision of PMS traffic
- On-line table handling
- Long term storage maintenance
o Provisions for electronic mail applications
o Adaption to external networks and hosts on the
message level.
The EMH provides the services to the following terminals,
hosts and external networks:
Terminals:
- Direct connected teleprinters (TTY)
- Concentrator network switched terminals (CRTS,
Printers)
Hosts:
- RES
- VIA
- SUPP
- RCCSH
External Networks:
- SITA
- ARINC
- CNT
- TELEX
4.9.2 E̲M̲H̲ ̲O̲p̲e̲r̲a̲t̲o̲r̲ ̲P̲o̲s̲i̲t̲i̲o̲n̲s̲
The Electronic Mail Host will be equipped with the
following terminal positions and peripheral equipment:
-4 PMS Supervisor positions, each with a standard
VDU
(formatted) with alphanumeric keyboard.
These positions are dedicated to PMS-message repair
and to EMH Supervisory functions.
-1 Lineprinter dedicated for PMS-message repair positions.
-1 Engineering position, with a standard VDU for electronic
mail S/W development and maintenance. The position
may be used as a backup PMS Supervisor pos.
-1 Lineprinter dedicated to the engineering position
-1 Magtape station for magtape backup of message files
and catalogues.
-1 DISC with removeable disc packs for backup purposes,
garbage collection and load sharing in critical
situations. An extra disc drive to be added in
1988.
4.9.3 D̲i̲s̲t̲r̲i̲b̲u̲t̲i̲o̲n̲ ̲o̲f̲ ̲E̲M̲H̲ ̲C̲o̲n̲t̲r̲o̲l̲
The EMH Control commands concern the below listed categories.
The commands are applicable to EMH Supervisors unlimited
and partly network users within subscriber office limits:
C̲o̲m̲m̲a̲n̲d̲ ̲C̲a̲t̲e̲g̲o̲r̲y̲:̲
o Device Control (Supervisor)
o Delivery Control (Supervisor and user)
o Routing table Control (Supervisor)
o Message entry (user)
o Message retrieval (Supervisor, user)
o Message repair (Supervisor, user)
o Handling of undeliv.Msgs. (Supervisor)
o Message File, Catalogue main-
tenance (Supervisor)
o Alarm Handling (Supervisor)
o Electronic Mail Applications (Engineer, Supervisor)
4.9.4 O̲p̲e̲r̲a̲t̲o̲r̲ ̲C̲a̲t̲e̲g̲o̲r̲i̲e̲s̲
As given in section 4.9.3 the EMH functions are applicable
to the following operator categories:
o EMH Supervisors
o Network users
o EMH engineers.
4.9.5 E̲M̲H̲ ̲F̲u̲n̲c̲t̲i̲o̲n̲s̲
The EMH provides the following groups of functional
capabilities:
- Direct Printer Traffic Delivery (TDP-Type B)
- Protected Message Switching (PMS-Type B)
- EMH Supervison
- Electronic Mail Service Provisions.
4.9.5.1 D̲i̲r̲e̲c̲t̲ ̲P̲r̲i̲n̲t̲e̲r̲ ̲T̲r̲a̲f̲f̲i̲c̲ ̲D̲e̲l̲i̲v̲e̲r̲y̲ ̲H̲a̲n̲d̲l̲i̲n̲g̲
The EMH provides store and forward service in the network
for non-ATA/IATA (or telex) formatted messages (TDP
messages - e.g. Tickets, Airwaybills).
When safely stored on disc an acknowledgement (on level
6) will be returned to the host via the network. The
EMH has hereby taken over responsibility for the TDP
message delivery.
The destination printer shall be addressed by the originating
host via the session set up for transfer of the TDP
message from host to EMH. The informations provided
by the host at this session setup shall be:
- destination printer address
- delivery priority level
- message burn time
Default values for message burn times may be specified
per priority by the EMH supervisor using the "device
configuration profile" update command.
The TDP message is enqueued for delivery on the printer
according to the priority (normally the highest priority
- default).
The TDP message is stored on temporary a disc file
until it is delivered to the printer or until it is
burnt.
The filereference is checkpointed for recovery in case
of serious EMH error, but no logging or journalization
will be provided for TDP messages. TDP messages cannot
be retrieved.
4.9.5.2 P̲r̲o̲t̲e̲c̲t̲e̲d̲ ̲M̲e̲s̲s̲a̲g̲e̲ ̲S̲w̲i̲t̲c̲h̲i̲n̲g̲
The Protected Message Switching functions handles the
ATA/IATA formatted narrative messages and telex messages.
The services provided are the following:
- Guaranteed automatic delivery and automatic routing
of messages
- Long term storage of messages for retrieval
- message entry handling
- Message repair functions
- Logging, journalization of delivered messages and
message flow statistics.
Messages formatted in ATA/IATA format are fully supported.
Important for the automatic delivery is the interpretation
of addresses, the routing scheme and the priority indicator.
The addressing (routing indicators) are 7 to 11 character
mnemonic's consisting of 3 to 5 character city/airport
code (1) 2 to 3 character office function indicator
and 2 to 3 character airline organization indicator.
The addresses refer to:
- a terminal or a group of terminals
- a host application
The addressing for Telex (recognized by the two first
charatcers: TX' are TX numbers on mnemomic address
like ATA/IATA traffic - both options are supported
fully.
All priority indicators defined for ATA/IATA are fully
supported.
4.9.5.2.1 G̲u̲a̲r̲a̲n̲t̲e̲e̲d̲ ̲A̲u̲t̲o̲m̲a̲t̲i̲c̲ ̲D̲e̲l̲i̲v̲e̲r̲y̲
When input to the system the messages are stored temporarily
on disc and checked for correct format. The addresses
are looked up and the message is stored on long term
storage and enqueued for delivery according to priority.
The message will remain in the delivery queue until
safely delivered to a printer, host or external network.
From the message entry (temporarity stored on disc
and acknowledge back to inputting originator) until
delivery at all destination devices full accountability
is provided by the EMH. This means that all references
to the message and queue entries are checkpointed and
will be restored in case of recovery.
End to end acknowledgement in the delivery process
will provide for guaranteed delivery. In case of interrupted
delivery due to line or network errors the message
will be retransmitted. Incomplete messages will be
handled according to the ATA/IATA QTA, QTB indicator
Procedures.
In case of format errors or procedure errors (too long
messages, too many addresses) the message i routed
to the reapir queue for messages originating from hosts
or external networks. Faulty messages originating from
network terminals are rejected back to the terminal
with indication of error. Correct formatted messages
are never routed back to the originator.
No hard limit it put on the size of message or the
addressing multiplicity. However delivery to external
networks put certain restrictions on the message. In
these cases the message is enqueued for repair and
may be split by the supervisor.
Adress stripping for messages to SITA and ARINC is
provided by the EMH. Messages which are addressed to
the same terminal device more than one time are only
delivered in one copy.
All messages delivered to terminals are supplied with
the following informations on hard copy:
- Serial output number (retrieval key)
- Time of delivery
- Time of storage on longterm storage (retrieval
key)
4.9.5.2.2 L̲o̲n̲g̲t̲e̲r̲m̲ ̲S̲t̲o̲r̲a̲g̲e̲ ̲o̲f̲ ̲M̲e̲s̲s̲a̲g̲e̲s̲ ̲f̲o̲r̲ ̲R̲e̲t̲r̲i̲e̲v̲a̲l̲
All messages entered for delivery are stored on long
term storage. Sufficient storage for at least 8 hours
will be provided.
The messages may be retrieved via catalogues according
to the following retrieval keys:
- Time range
- Serial input number
- Serial output number
For terminal users and supervisors the following general
rules for retrieval apply:
- Terminal users may retrieve messages originated
or delivered to that specific terminal.
- Supervisors may retrieve all messages.
Retrieved catalogues for 24 hours may be requested
per terminal or for all terminals.
4.9.5.2.3 M̲e̲s̲s̲a̲g̲e̲ ̲E̲n̲t̲r̲y̲ ̲H̲a̲n̲d̲l̲i̲n̲g̲
This section describes the message entry facilities
provided to a network terminal user. The facilities
are:
o Enter (ENT) of message
o Retrieve for hardcopy output (RTR)
o Retrieve for display (RTD)
o Edit message (EDI)
o Release edited message for delivery (REL)
E̲N̲T̲
The enter command is used for batchmode entry from
the terminals. The command may be presented differently
depending on the terminal device. For entry via VDU's
several screens of text may be input by means of next
screen function key.
The messages are entered in free format. Guided message
preparation may be offered as an option. When the EMH
has accepted the message acknowledgement is given back
to the originator in form of
- Serial output number
- Time of storage.
In case of format errors an 'reject' message is sent
back to the originator containing the following informations:
- Error description/line number
- Preliminary serial output number.
In this state the message is not stored on longterm
storage but on temporary storage from which it may
be retrieved by prelim. serial output number for editing
and subsequent release. A total of 5 such messages
may exist per terminal.
R̲T̲R̲
This retrieval command is used for retrieval with hardcopy
output. The retrieval keys are:
- Time range /Time
- Serial input/output number.
If more than 5 matches the retrieval is rejected and
a more specified retrieval key must be given. The message
log may be browsed by the operator.
R̲T̲D̲/̲E̲D̲I̲
This command is used for retrieval for display. The
retrieval keys are
- The same as for RTR for delivered messages
or - the preliminary serial output number for erroneous
messages
or - an identification of preformatted message.
If more than 1 match and less than 5 matches the operator
is requested for "specific message". If more than 5
matches the operator is requested for more specific
keys.
When one specific message or format is retrieved this
is copied to temporary storage from which it is displayed
and to which it may be edited.
After edit the message may be released for distribution.
Each subscriber may install a pool of preformatted
messages (formulars) which can be retrieved, edited
and released for delivery. This facility will ease
the writing of standard messages
The editing facility is applicable to temporarity stored
messages.
The editing may take place in free format and may employ
all the local editing facilities offered by the different
terminal types. The following edit types:
- Delete line(s)
- Insert line(s)
- Change line(s)
- Move line(s)
- Add line(s)
are supported. Preformatted messages may use protected
fields.
Retrieval for distribution is accomplished by editing
the address header.
The procedure may be cancelled at any stage in the
retrieval editing process. This will clear up the temporary
files.
R̲E̲L̲
The release procedure is applicable for temporarily
stored messages. It simply releases the message for
delivery corresponding to ENT. The message will be
treated like a new message although it may originate
from a retrieval.
4.9.5.2.4 M̲e̲s̲s̲a̲g̲e̲ ̲R̲e̲p̲a̲i̲r̲ ̲F̲u̲n̲c̲t̲i̲o̲n̲s̲
Erroneous messages originating from external networks
or hosts are enqueued to the Supervisory repair queue
(according to priority). This queue is serviced interactively
by the EMH Supervisors using the repair function.
The messages sent for repair are stored on temporary
storage and are entered on longterm storage after successful
repair.
The messages for repair are presented one by one to
the supervisors in priority order. The presented informations
are:
o Reason for intercept
- Format errors (specified)
- Invalid address
- Too many addresses
- Too long message
- Others
o Line number of error(s)
o Message text (line numbered).
The repair operator may perform the following functions
to the message:
o Edit in free format (like in 4.9.5.2.3)
o Reenter message
o Dump to printer
o Purge message
o Split message.
4.9.5.2.5 L̲o̲g̲g̲i̲n̲g̲,̲ ̲J̲o̲u̲r̲n̲a̲l̲i̲z̲a̲t̲i̲o̲n̲ ̲a̲n̲d̲ ̲S̲t̲a̲t̲i̲s̲t̲i̲c̲s̲
Network terminal users may retrieve a terminal specific
message log for the last 24 hours. The log lists the
following informations for that specific terminal:
-Per message received
o Serial input no.
o Time of storage
-Per message sent
o Serial output no.
o Time of storage.
EMH Supervisors may list the same informations per
specified terminal or group of terminals or for the
entire traffic of the EMH.
EMH generated statistics are included in section 4.11.
4.9.5.3 E̲M̲H̲ ̲S̲u̲p̲e̲r̲v̲i̲s̲o̲r̲y̲ ̲F̲u̲n̲c̲t̲i̲o̲n̲s̲
The supervisory procedures provided by the EMH are
the following:
o Table Handling
- Device Tables
- Addressing Tables
o Delivery Control
o Alarm Supervision
o Storage Maintenance
4.9.5.3.1 T̲a̲b̲l̲e̲ ̲H̲a̲n̲d̲l̲i̲n̲g̲
The Table Handling functions are provided to the Device
Control Tables and to the Addressing Tables.
Each physical or logical device has a device control
block associated. This control block contains information
about:
o Device type, terminal type
o Delivery status
o Device status
o Other device characteristics
These tables may be edited, added, deleted on-line
by the EMH supervisor using guided interactive procedures
which will ascertain the table consistency.
The addressing tables contain the relations between
mnemonic addresses and terminal identifications.
These tables may be updated online by the EMH supervisor
using guided interactive procedures assuring table
integrity. Each table entry may be subject to:
o Addition
o Deletion
o Change
4.9.5.3.2 D̲e̲l̲i̲v̲e̲r̲y̲ ̲C̲o̲n̲t̲r̲o̲l̲
Procedures for delivery control is provided to network
users as well as EMH supervisors.
The delivery control procedures correspond to those
of the existing network:
o Hold
o Skip
o Alternate Route
o Duplicate Delivery
Furthermore, the supervisors will have a set of output
queue control procedures for:
o Reorganize queue
o Move queue
The procedures of the existing network for draining
specified terminal queues to tape is also provided
by the EMH. The "drain" media may be tape or removeable
disc.
4.9.5.3.3 A̲l̲a̲r̲m̲ ̲S̲u̲p̲e̲r̲v̲i̲s̲i̲o̲n̲
The three first lines of a supervisor VDU are reserved
for alarm display.
All alarms are logged and may be printed on request.
The alarms forwarded to an EMH supervisor are the following:
o Open circuit alarm
o Mark Hold Alarm
o Circuit Failure Alarm
o Queue Overflow Alarm
o Congestion Alarm
(lack of buffers and other resources)
o Disc Failures/Tape Failures
o Host Failures
o External Network Failures
4.9.5.3.4 S̲t̲o̲r̲a̲g̲e̲ ̲M̲a̲i̲n̲t̲e̲n̲a̲n̲c̲e̲
The Storage Maintenance functions concern the functions
of backing-up message files and catalogues to tape
or to removeable disc pack.
4.9.5.4 E̲l̲e̲c̲t̲r̲o̲n̲i̲c̲ ̲M̲a̲i̲l̲ ̲S̲e̲r̲v̲i̲c̲e̲s̲
The EMH is a general purpose computer and the operating
system DAMOS provides for security protection enabling
user defined application development and use of electronic
mail applications without interferring with the PMS
services.
The basic operating system services for PMS applications
are also available for user defined applications.
These services comprise the following functions:
o Monitors for allocation of disc and memory resources
o Monitors for allocation of message control blocks,
message queues or lists (mailboxes) and temporary
message files
o Programs for storing/retrieving messages on permanent
files
o Monitors for accessing messages, message control
blocks and for performing queue or list functions
4.9.6 N̲e̲t̲w̲o̲r̲k̲ ̲G̲a̲t̲e̲w̲a̲y̲s̲
The EMH provides access to the following external networks:
o SITA
o ARINC
o CNT
o TELEX
The link level access to these networks are physically
provided in the nodes and the message level protocols
are handled by the EMH.
The functional specification of these interfaces are
described in section 6.9 "External Network Access Software
- ENAS".
