ITU-T I.324 PDF

General

Basic philosophy

The objective of this Recommendation is to provide a common understanding of the CCITT studies on the general architecture of an ISDN from the functional point of view. The model is not intended to require or exclude any specific implementation of an ISDN, but only to provide a guide for the specification of ISDN capabilities.

Definitions

A number of terms used in this Recommendation are described in more detail in other Recommendations. To assist the understanding of the reader, the following particular definitions apply in this Recommendation:

1) reference configurations are conceptual configurations which are useful in identifying various possible arrangements in an ISDN. The reference configurations are based on association rules of functional groupings and reference points. Detailed descriptions of reference configurations for ISDN connection types are given in other I-Series Recommendations. For user-to-network access they are defined in Recommendation I.411 and for interworking between networks they are defined in the I.500-Series of Recommendations.

2) functional groupings are sets of functions which may be needed in ISDN arrangements. The relationship between generic functions and specific functions allocated to particular entities (or functional groupings) in the ISDN are explained in Recommendation I.310.

3) reference points are the conceptual points at the conjunction of two functional groupings. In a particular example, a reference point may correspond to a physical interface between pieces of equipment, or in other examples, there may not be any physical interface corresponding to the reference point. Interfaces will not be defined by CCITT for an ISDN unless the corresponding reference points have been already specified.