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The drawings contain in this Recommendation have been done in Autocad.
SECTION 2
TEST SPECIFICATION
Recommendation Q.780
SIGNALLING SYSTEM NO. 7 TEST SPECIFICATION
GENERAL DESCRIPTION
1 General
This Recommendation is an introductory Recommendation to the test
specifications of Signalling System No. 7. The test specifications are contained
in Recommendations Q.781-Q.783. This Recommendation defines the scope and purpose
of the test specification and identifies guidelines that are either specific to
the particular protocol under test, or are more general. In addition it
identifies functional requirements imposed by the test specification.
2 Geneal principles of test specifications
The test specification aims at testing protocol conformance in a given
implementation. This is independent of a given implementation and does not
generally imply any modification of the signalling point under test. However, it
is recognized that certain tests require capabilities of the system that are not
explicitly defined in the relevant Recommendation, and these capabilities may not
be present in all implementations. As a consequence, certain tests may not be
possible in all implementations.
3 Scope of the test specification
The test specification is intended to cover all aspects of Signalling
System No. 7. However the initial Recommendations cover the message transfer part
Q.701-Q.707, and the telephone user part Q.721-Q.724. The test specification is
not a definition of the protocol, this is contained in Recommendations
Q.701-Q.707 and Q.721-Q.724 as appropriate.
4 Field of application
The test specification applies in the international network, and if
appropriate in the national network. In the international network, the actual
tests to be performed will be the subject of appropriate bilateral agreements
beween the two or more Administrations/RPOAs concerned.
5 Method of application
The test specification fulfils the requirements for both validation
testing and compatibility testing. See SS 5.1 and 5.2 for an explanation of these
terms.
All tests in the test specification are validation tests (VAT), and in
addition those marked with an asterisk are also compatibility tests (CPT).
5.1 Validation testing
The function of validation testing is to check that a given implementation
conforms to the relevant CCITT Recommendations of the Signalling System. These
validation tests could apply both in the national and international networks. The
validation test is a pre-requisite of compatibility testing (see S 5.2) and is
performed under the responsibility of each Administration/RPOA. These tests will
generally be performed without the cooperation of another Administration/RPOA,
although this is not precluded should this arrangement prove convenient.
Validation testing will be performed on a signalling point that is not in
service.
The validation test is performed on one signalling point.
It is suggested that the validation test, or subset, is repeated when the
implementation is upgraded or modified in any functional way.
Validation testing may require the use of a simulator to check the
operation of the signalling point under test. The specification of this simulator
is not explicitly covered by these Recommendations although the general
requirements are implicit in the test specification.
In validation testing, the signalling point under test is called SP"A".
5.2 Compatibility testing
The objective of compatibility testing is to check for the correct
interworking of two implementations. To perform compatibility testing the two
nodes involved are interconnected. The specification is written for the
interconnection of two given implementations for the first time. For subsequent
interconnections of the same two implementations a subset of tests may prove
sufficient. These tests will not only be performed on a new signalling point, but
also on a signalling point already in service.
Each Recommendation identifies a list of tests that may be suitable for
Fascicle VI.9 - Q.780 PAGE135
compatibility testing, but the actual tests to be performed will be bilaterally
agreed between the Administrations/RPOAs concerned.
Certain of the tests identified in the test list as compatibility test may
disturb the operation of the exchange, whereas others may not. Any tests which
may cause disturbance to the exchange should be carefully selected to meet the
operational criteria of the two Administrations/RPOAs.
The satisfactory completion of compatibility testing should be bilaterally
agreed.
When a change to the signalling network is made, tests selected from those
identified as compatibility tests may be appropriate. In general the tests
performed under these circumstances will be the minimum number to ensure that
compatibility between points in the network is still maintained.
In compatibility testing, each signalling point may in turn consider
itself to be SP"A", i.e. tests are performed on both signalling points involved.
5.3 Test configuration
For both validation and compatibility testing the point under test is
connected to the test environment and becomes part of the "test configuration".
The test configuration satisfies all of the following three criteria:
- The point under test will be connected by one or more signalling
linksets (real or simulated), which may or may not be interconnected.
- The capability of generation and reception of test traffic, where
applicable.
- The ability to perform the described test, notably the facility to
store and analyze messages to the appropriate degree.
6 Functional requirements imposed by the test specification
The functional description that follows is intended to identify the
functional requirements imposed by the test specification. It does not imply any
physical partitioning of equipment in real systems. See also Recommenda-
tion Q.701, S 2.2.1.
6.1 Level 1
The test specification assumes the availability of a suitable signalling
data link with the parameters identified in the relevant Q Recommendations, e.g.
Q.702 (referring to Recommendation G.821).
In validation testing the signalling data link may be a pseudo-signalling
data link, in which case it should preferably have similar/identical
characteristics to the signalling data links likely to be encountered in service.
Simulation of deterioration of the transmission link may not be necessary if the
emulator includes the capability to simulate abnormal conditions on the
signalling data link.
In compatibility testing the signalling data link is the actual signalling
data link that will be used in service.
6.2 Level 2
The level 2 test environment consists of four items (see Figure 1/Q.780):
- the level 3 simulator;
- the test simulator;
- the signalling link monitor (see S 7);
- the signalling data link.
6.2.1 Level 3 simulator
During the level 2 tests it is necessary to inject signalling messages and
indications to and from the level 2 under test. It is desirable that the level 3
function used is the actual level 3 of the MTP with some additional functions for
test purposes.
6.2.2 Test simulator
During level 2 testing it is necessary to inject some abnormal signal
units (as well as normal signal units) to fully test the level 2 under test, the
test simulator should have this function. In addition the simulator should have
the capability to receive and check signal units from the level 2 under test. The
generation of certain abnormal sequences of signal units should also be a
capability of the test simulator.
6.3 Level 3
The level 3 test specification assumes that the level 2 has already been
tested satisfactorily. However, certain tests will in addition explicitly test
the level 2/3 interface.
The level 3 test environment consists of 3 items (see Figure 2/Q.780):
- the simulator of upper levels;
PAGE136 Fascicle VI.9 - Rec. Q.780
- simulated network including test simulator and signalling data links;
- the signalling link monitor(s) (see S 7).
6.3.1 Simulator of upper levels
the
the simulator used should be as close as possible to the actual upper level to be
used. In addition an MML interface is assumed. The level 3 under test must use an
already tested level 2.
6.3.2 Simulated network including test simulator
During level 3 testing it is necessary to inject some abnormal messages
(as well as normal messages) to check the level 3 under test, the simulated
network including test simulator should have this function. In addition the test
simulator should have the capabilities to receive and check messages from the
level 3 under test. The generation of certain abnormal sequences of messages
should also be a capability of the test simulator. The test simulator must
include an already tested level 2.
6.4 TUP
The TUP test specification assumes a tested MTP for compatibility tests
but no assumption is made about message transfer between the TUP under test and
the TUP tester for validation tests.
The TUP test environment consists of three items (see Figure 3/Q.780):
V the TUP tester;
V a stable signalling relation and telephone circuits;
V a monitor of TUP messages and telephone circuits.
6.4.1 TUP tester
The TUP tester is required to simulate TUP protocol operations and some
exchange call control operations.
6.4.2 Monitor
The monitor is required to monitor and record TUP message sequences and to
monitor the result of call control operations on the controlled telephone
circuits. This includes checking that tones are correctly received and that
speech/information transfer is possible.
7 Signalling link monitor(s)
The test specification assumes the availability of a signalling link
monitor and a suitable access point for connection of the monitor as specified in
Recommendation Q.702, ' 4.
The test specification does not attempt to specify what a signalling link
monitor should be, but instead the functional requirements are identified in
general terms. A signalling link monitor will be used for decoding of signal unit
sequences during testing and to give the operator confidence that the signalling
protocol has been correctly observed.
The requirements imposed on a signalling link monitor will be different
for the two types of testing. For validation testing detailed decoding down to a
field level will be required, but for compatibility testing decoding down to a
message level may be adequate.
In addition it should be noted that compatibility testing will be a
function performed numerous times on a signalling point, whereas validation
testing will be performed once only, except under certain circumstances of
upgrading of the signalling point.
Note V It should be oserved that implementations may include a signalling
link monitor as an intrinsic part of the signalling point, however, for
validation testing this cannot necessarily be relied upon. In addition, the test
specification does not attempt to perform the function of testing the accuracy of
any signalling link monitor implemented in the signalling point, however, certain
conclusions will inevitably be made from the performance of validation testing.
Fig.1/Q.780 /T1109810-88 = 9.5 cm
Fig.2/Q.780 /T1109820-88 = 9.5 cm
Fig.3/Q.780 /T1109830-88 = 7 cm
Fascicle VI.9 - Q.780 PAGE135