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Understanding IEC 13247-01: The B-PISN Signalling Standard (ISO/IEC 13247:2001 / CAN/CSA-ISO/IEC 13247-01)
A comprehensive guide to the protocol architecture, message definitions, and compliance requirements for broadband private networking.
Scope and Application
ISO/IEC 13247:2001, known formally in Canada as CAN/CSA-ISO/IEC 13247-01 and identified by its project designation IEC 13247-01, specifies the signalling protocol for basic call/connection control at the Q reference point between PINXs (Private Integrated Services Network Exchanges) in a Broadband Private Integrated Services Network (B-PISN). This standard is a cornerstone of the ISO/IEC 13240 series which defines the B-PISN environment.
The standard strictly defines how terminal endpoints and inter-exchange systems communicate to establish, maintain, and release broadband connections. It is functionally aligned with the ITU-T Recommendation Q.2931 but has been specifically tailored for the private networking domain, addressing the unique requirements of enterprise telecommunications infrastructure such as resource allocation, private numbering, and security mechanisms.
Technical Architecture and Protocol Stack
The protocol defined by this standard operates at Layer 3 of the OSI model. It requires a reliable signalling transport mechanism, typically provided by the Signalling ATM Adaptation Layer (SAAL) over an ATM backbone. The standard meticulously specifies the structure of messages, the procedures for call handling, and the encoding of information elements.
Message Types
The protocol employs a discrete set of messages transmitted across the network to manage the call state. Each message is identified by a unique message type code.
| Message | Code | Function |
|---|---|---|
| ALERTING | 0000 0001 | Indicates that the called user has been alerted. |
| CALL PROCEEDING | 0000 0010 | Indicates that the requested call establishment has been initiated. |
| CONNECT | 0000 0111 | Indicates that the call has been accepted by the called user. |
| CONNECT ACKNOWLEDGE | 0000 1111 | Acknowledges the receipt of the CONNECT message. |
| RELEASE | 0101 1101 | Initiated to clear an end-to-end connection and release resources. |
| RELEASE COMPLETE | 0101 1010 | Acknowledges the RELEASE message, confirming resource release. |
| SETUP | 0000 0101 | Initiates a call establishment request. |
| STATUS | 0111 1101 | Reports the status of the call or the protocol entity. |
| STATUS ENQUIRY | 0111 0101 | Requests the status of the call or the protocol entity. |
Information Elements
Each message carries a set of Information Elements (IEs) that convey the necessary parameters for call control. According to ISO/IEC 13247, these IEs are mandatory or optional depending on the message. For instance, a SETUP message must contain specific mandatory IEs.
- AAL Parameters: Describes the ATM Adaptation Layer protocol configuration.
- ATM Traffic Descriptor: Specifies the traffic contract (e.g., Peak Cell Rate, Sustainable Cell Rate).
- Broadband Bearer Capability: Defines the bearer service characteristics (Bearer Class A through X).
- Called Party Number: The destination address of the call.
- Connection Identifier: Identifies the connection (e.g., VPI/VCI values).
Implementation Highlights
Implementing ISO/IEC 13247 requires strict adherence to the protocol state machine. The standard defines a finite state machine for each call and connection endpoint. Correct sequencing of messages is critical to