 by means of dynamic configuration. A rather interesting paradox is that TM network technologies (data communication network, servers, etc.) strongly evolve towards IP, while the system structure becomes closer to the hierarchical TMN (OMCs and NMC) mainly due to the increasing size and diversity of managed networks. A short summary of terms associated with both approaches on management is given below: Enablers and terminology TMN - Telecommunications Management Network NMS - network management system NMC - network management centre OMC - operation and maintenance centre TMN Telecommunications management network Data communication network Network Network Network Network Network element element element element element Telecommunication network Figure 16.5 An illustration of the TMN model (OSS: operation support system) Understanding Changing Telecommunications - Building a Successful Telecom Business OSS - operations support system NE - network element Q3 interface MO - managed objects SMI - structure of management information MIT - management information tree CMIP - common management information protocol FTAM - file transfer, access and management 'Internet' standards NEs, managed objects and MIT (as for TMN, but Q3 interface usually not mentioned) SNMP - simple network management protocol Web protocols - HTTP (hyper text transfer protocol) and HTML (hyper text mark-up language) FTP - file transfer protocol LDAP - lightweight directory access protocol RADIUS - remote access dial in user service L2TP and L3TP - label 2/3 tunnelling protocol IP security Standards from IT industry CORBA - common object request broker architecture EDI - electronic data interchange XML - extensible mark-up language SSL - secure socket layer SQL - simple query language Network Elements, Managers and Agents When talking about TM we are referring to managed networks. Managed networks consist of a number of network elements or managed devices and a manager. Managed devices collect and store management information for the centralized manag