scope:

Introduction

The NGN architecture defined in Recommendation ITU-T Y.2012 [1] is a generalized architecture in which abstract functional entities are specified. However, to address the issues of interoperability within an NGN network, there is a need to identify physical realizations showing which functional entities are implemented in a network component and by implication the interfaces that are important to ensure the interoperability of systems. This document is intended to give guidance on the physical realisation of Next Generation Networks by describing a number of possible physical entities corresponding to a functional entity or a group of functional entities specified in the generalised functional architecture of NGN.

Chapter 2 describes the NGN architecture and functions defined in terms of various functional entities and chapter 3 gives examples of physical components in which these functional entities may be realised. Reference is made to Recommendation ITU-T Q.3900 [2] that describes the mapping of NGN functional entities into physical components for the purpose of defining a model for the testing of NGN equipment and Supplement 2 to Recommendation ITU-T Y.2012 that describes the realisation of Session Border Controllers in an NGN environment [15].

More detailed information on NGN, in particular on the protocol mechanisms employed, can be found in the ITU-T Handbook on NGN "Converging Networks" [3].