 Information conversion function d. Human machine adaptation e. Presentation function f. Message communication function (MCF) The interactions between the function blocks in TMN functional architecture are shown in Figure 2.3. 2.4 Physical Architecture While the functional architecture defines the management functions, the physical architecture defines how the management functions can be mapped to physical equipment. When function blocks are mapped to building blocks (physical enti- ties), the references are mapped to interfaces. TMN Model Hence the physical architecture consists of building blocks and interfaces. Building blocks represent physical node in the TMN, whereas interfaces define the information exchange between these nodes. Physical architecture defines the following building blocks: Operations system (OS) Mediation device (MD) Q-adapter (QA) Network element (NE) Work station (WS) Data communication network (DCN) 1. Operations system or support system (OS): Perform operations system func- tions (OSF). The os can also provide some of the mediation, q-adaptation, and workstation functions. 2. Mediation device (MD): Performs mediation between TMN interfaces and the OS. Mediation function, as already discussed in functional architecture, may be needed to ensure that data is presented in the exact way that the OS expects. Mediation functions can be implemented across hierarchies of cascaded MDs. 3. Q-adapter (QA): The QA is used to manage NEs that have non-TMN interfaces. The QA translates between TMN and non-TMN interfaces. For example, A TL1 Q-adapter translates between a TL1 ASCII message-based protocol and the common management information protocol (CMIP); simi- larly a simple network management protocol (SNMP) Q-adapter translates between SNMP and CMIP. 4. Network element (NE): An NE contains manageable information that is monitored and controlled by an OS. It performs network element functions (NEF) specified in functional architecture. 5. Workstation (WS): The WS performs workstation functions (WSF)