nt manager is a piece of software which can control large extent, on the functions which each of the network elements many individual network elements (usually in the range 10-1000), actually perform. This is where the network element functional but it can only control them as individual elements and does not standards, CCITT G.781/2/3, come in. These are the recommenda- have any view of the traffic relationships between them. Usually it tions which describe how the functionality of a network element can is located remote from the elements it is controlling and more often be decomposed into the basic 'atomic' elements of functionality, than not, it runs on some form of workstation. The interface between together with how such atomic functions may be combined and the element manager and the network elements is an obvious area thereafter exchange both traffic and control information. (See Fig- for standardisation, as without this there is little chance of a single ure 42.22.) element manager controlling network elements from more than one The rules for combination of these atomic functions enable a manufacturer. Despite the progress that has been made in rigorously variety of network elements to be synthesised, with differing traffic describing the network element atomic functions, it has still proved capacities and routing capabilities. Indeed, one of the current prob- very difficult to agree on a software description of them. The lems is the potentially large number of different ways a comformant approach adopted in CCITT, ANSI, and ETSI has been to describe network element can be constructed. It is rather difficult for soft- complete network elements as collections of 'objects' in line with ware based control systems to cope with this variety and hence there the rules of 'object orientated' programming. are efforts in several standards fora (notably ETSI), to standardise The idea is that an object is a software entity that has both on a more restricted range of network element functionalities. attributes and beh