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Comprehensive Guide to CAN/CSA-ISO/IEC 11572-01: Private Integrated Services Network (PISN) Circuit Mode Bearer Services Inter-Exchange Signalling – Test Suite Structure and Test Purposes
Understanding the Testing Framework and Compliance Requirements for PISN Signalling Protocol Implementation
Scope of CAN/CSA-ISO/IEC 11572-01
CAN/CSA-ISO/IEC 11572-01 is the Canadian adoption of the international standard ISO/IEC 11572-1, which defines the Test Suite Structure and Test Purposes (TSS&TP) for the signalling protocol used in Private Integrated Services Network (PISN) circuit-mode bearer services. This standard specifically addresses inter-exchange signalling procedures and protocols based on the Digital Subscriber Signalling System No. 1 (DSS1) and is applicable to Private Integrated Services Network Exchanges (PINX) that operate in accordance with the PISN reference model.
The TSS&TP framework provides a systematic basis for conformance testing. It specifies test purposes that cover the behaviour of the protocol at the PISN interface, including the establishment, maintenance, and release of circuit-mode connections, as well as supplementary services such as calling line identification, call forwarding, and call hold. The standard is designed to ensure interoperability between PINX equipment from different vendors, thereby supporting seamless communication in corporate and multi-site networks.
Key Point: Although ISO/IEC 11572-1 is a testing standard, it references the protocol specification of the base standard (ISO/IEC 11572:1997). Implementers must also consult that document to understand the full protocol behaviour.
Technical Requirements
CAN/CSA-ISO/IEC 11572-01 presents a structured set of test purposes grouped into a Test Suite Structure (TSS) defined by service primitives and protocol states. The TSS is partitioned into the following test groups:
- Basic Call Control (GRP_BCC): Tests for call establishment, alerting, connection, clearing, and abnormal conditions.
- Supplementary Services (GRP_SS_1, GRP_SS_2, GRP_SS_3): Tests for services such as CLIP, CLIR, CFU, CFB, CFNR, HOLD, and RETRIEVE.
- Protocol Messages and Information Elements: Validation of mandatory and optional message fields (e.g., Bearer Capability, Channel Identification).
- State Machine Verification: Behavioural tests ensuring correct transitions across Outgoing and Incoming call states.
The following tables illustrate the test group structure and a selection of test purposes for basic call control:
| Group ID | Group Name | Number of Test Purposes | Description |
|---|---|---|---|
| GRP_BCC | Basic Call Control | 120 | Verify call establishment, clearing, and abnormal procedures |
| GRP_SS_1 | Calling Line ID Services | 30 | Test CLIP and CLIR functionalities |
| GRP_SS_2 | Call Forwarding Services | 45 | Test CFU, CFB, CFNR |
| GRP_SS_3 | Call Hold & Retrieve | 20 | Test HOLD and RETRIEVE operations |
| Test Reference | Test Purpose | Message / Event | Expected Outcome |
|---|---|---|---|
| TCC_BAS_01 | Verify that a SETUP message with valid mandatory information elements triggers a CALL PROCEEDING message | SETUP (outgoing) | IUT sends CALL PROCEEDING |
| TCC_BAS_05 | Verify that the IUT correctly processes a CONNECT message and enters the Active state | CONNECT (incoming) | IUT sends CONNECT ACKNOWLEDGE |
| TCC_BAS_10 | Verify that a RELEASE sent during the Active state is acknowledged with RELEASE COMPLETE | RELEASE (either direction) | IUT responds with RELEASE COMPLETE |
| TCC_BAS_15 | Verify that the IUT rejects an invalid SETUP message containing a duplicate information element | SETUP (invalid) | IUT sends RELEASE COMPLETE with cause #100 |
Each test purpose is defined in an abstract manner, specifying the initial state, preconditions, actions, verification criteria, and final state. The standard does not mandate a particular test architecture but expects the implementation to support remote testing as defined in ISO/IEC 9646 (OSI Conformance Testing Methodology). The test purposes also reference timers (e.g., T301, T302, T303, T305, T306) that must behave within specified ranges.
Implementation Note: The test purposes in CAN/CSA-ISO/IEC 11572-01 are abstract. When developing a PICS (Protocol Implementation Conformance Statement) and corresponding test system, it is necessary to map these test purposes to concrete test cases that account for specific hardware and software stacks.
Implementation Highlights
Implementing a PINX that complies with CAN/CSA-ISO/IEC 11572-01 requires careful attention to the protocol specification and its testable aspects. The following highlights are critical for successful implementation:
Protocol State Machine
The standard defines state machines for both outgoing and incoming calls. These states (e.g., Null, Call Initiated, Outgoing Call Proceeding, Call Delivered, Active, Disconnect Request) must be accurately implemented to pass the TSS&TP tests. The test purposes check specific transitions, so any deviation will likely cause failure in conformance testing.
Information Element Encoding
Mandatory information elements such as Bearer Capability, Channel Identification, and Progress Indicator must be encoded according to the protocol standard. Test purposes verify the presence and correct coding of these IEs. Implementers should pay special attention to bit-level encoding as specified in ISO/IEC 11572 (base).
Timer Compliance
The standard uses timers to control call progress. The test purposes verify that the IUT respects these timers. In test cases involving abnormal termination, correct expiration behaviour must be demonstrated. For example, timer T303 (used to wait for a response to SETUP) must expire within the allowed range if the IUT does not receive CALL PROCEEDING.
Best Practice: Early integration of conformance testing using the TSS&TP of CAN/CSA-ISO/IEC 11572-01 can reduce interoperability issues at later stages. Ensure that your PICS covers all mandatory functions declared in the standard. Developers can also use the test purposes as a detailed checklist during implementation.
Compliance Notes
To claim conformance to CAN/CSA-ISO/IEC 11572-01, manufacturers must demonstrate that their PINX implementation passes the test purposes defined in the TSS&TP. This typically involves:
- Developing a Protocol Implementation Conformance Statement (PICS) that lists all supported features and test groups.
- Submitting the equipment to a qualified test laboratory that employs a test system implementing the test purposes.
- Ensuring that any claimed supplementary services also pass their respective test groups.
- Reviewing compliance with the base protocol standard ISO/IEC 11572 to ensure consistent base behaviour.
Caution: Failure to meet mandatory test purposes can result in non-compliance, which may bar the product from being marketed as conforming to CAN/CSA-ISO/IEC 11572-01. This can also affect interoperability with other PISN equipment and lead to service disruption in multi-vendor networks.
It is important to note that conformance to CAN/CSA-ISO/IEC 11572-01 does not guarantee full functional interoperability in all network configurations. However, it provides a strong baseline for verifying the correct implementation of the inter-exchange signalling protocol and is a key component for achieving PISN compliance under Canadian and international standards.
Compliance Tip: The test suite may be updated periodically. Always reference the latest edition of CAN/CSA-ISO/IEC 11572-01 as well as any amendments issued by the Standards Council of Canada. Also verify that your test equipment supports all required abstract test methods (e.g., remote test method).
Frequently Asked Questions
Q: What is the difference between CAN/CSA-ISO/IEC 11572-01 and ISO/IEC 11572-1?
A: CAN/CSA-ISO/IEC 11572-01 is the identical adoption of ISO/IEC 11572-1 by the Standards Council of Canada under the authority of the Canadian Standards Association (CSA Group). The content is the same, but it includes Canadian administrative front matter and is recognized as a national standard of Canada.
A: CAN/CSA-ISO/IEC 11572-01 is the identical adoption of ISO/IEC 11572-1 by the Standards Council of Canada under the authority of the Canadian Standards Association (CSA Group). The content is the same, but it includes Canadian administrative front matter and is recognized as a national standard of Canada.
Q: Is this standard applicable to all types of PISN inter-exchange signalling?
A: CAN/CSA-ISO/IEC 11572-01 specifically focuses on circuit-mode bearer services using the inter-exchange signalling protocol defined in ISO/IEC 11572 (base standard). It does not cover packet-mode services or user-to-user signalling. Other parts in the ISO/IEC 11572 series address those aspects (e.g., Part 2 for packet-mode).
A: CAN/CSA-ISO/IEC 11572-01 specifically focuses on circuit-mode bearer services using the inter-exchange signalling protocol defined in ISO/IEC 11572 (base standard). It does not cover packet-mode services or user-to-user signalling. Other parts in the ISO/IEC 11572 series address those aspects (e.g., Part 2 for packet-mode).
Q: How should I use this standard during product development?
A: The TSS&TP in this standard is primarily intended for conformance testing by independent test laboratories. However, developers can use the test purposes as a checklist for implementation and debugging. By systematically verifying each test purpose during development (from basic call establishment to advanced supplementary services), the likelihood of passing formal certification is greatly increased.
A: The TSS&TP in this standard is primarily intended for conformance testing by independent test laboratories. However, developers can use the test purposes as a checklist for implementation and debugging. By systematically verifying each test purpose during development (from basic call establishment to advanced supplementary services), the likelihood of passing formal certification is greatly increased.