Specification of Legacy Signalling Via ATM
Scope Of Specification

The following is an extract from our Specification of Legacy Signalling Via ATM:

"Based on the principles defined in the ATM Forum's specification of ATM trunking for narrowband services, this specification defines the necessary adaptation functions to permit narrowband Private Integrated services Network eXchanges (PINX) to be attached to and to support "legacy signalling via" ATM networks. These adaptation functions include:

• physical and electrical characteristics of the interfaces to the transmission systems to be employed for such procedures;
  
• procedures to ensure error-free communications links;
  
• procedures for call establishment and clearing; and
  
• generic procedures for the support of supplementary services.

The scope of the Specification is to provide a mechanism to permit "legacy" customer premise equipment (e.g., PABX and data equipment) using common channel signalling systems (such as DPNSS and QSIG) to be used in a broadband / ATM environment.

This Specification supports concatenation of 64 kbit/s narrowband Private Integrated Services Network (N-PISN) via B-ISDN and 64 kbit/s N-PISN to B-ISDN connections - scenarios 1 and 2 respectively of ITU- T Recommendation I.580. Further detail for scenario 2 is specified in the ATM Forum's trunking for narrowband services specification.

The Specification covers the following:

• fundamental protocol concepts and building blocks, including mapping of the protocol to physical network scenarios, individual layer aspects, syntax and coding aspects;
  
• the Basic call functionality and the basic telecommunication services supported by each protocol; and,
  
• the generic procedures for the support of supplementary services and the way these are applied in transit nodes and end nodes.

"Local switching" between equipments attached to the narrowband side of the AGS is outside the scope of this Specification.

The support of Attached Equipment using channel associated signalling systems is outside the scope of this Specification.

Adaptation functions for specific supplementary services are outside the scope of this Specification.

The scope of this document is limited to network interworking i.e., service interworking is not within the scope of this document.

Network management aspects pertaining to the various functions of the AGS, and the Management Information Base (MIB) to support these aspects are outside the scope of this Specification.

This Specification is not a complete specification of all functions of an ATM Gateway System.

The functions to be provided are defined within a framework based on that defined by the reference configuration for PISN eXchanges described in ISO/IEC 11579-1 (which defines a reference configuration for equipment providing automatic connection handling functions for the provision of telecommunications services).

Clause 4 defines the architectural framework used within this Specification and briefly describes each of the major functions to be supported for an instance (i.e., a call) of legacy signalling. Subsequent clauses (5 - 11) define in detail the requirements to be met by each of the major functions."

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Copyright © PQM Consultants 1998. This page was last updated on 27 May 1998.