7.4 Physical Architecture

According to the concept, the management network (TMN) is separated from the communication networks and is connected to the telecommunications network via an interface. However, the concept allows the use of a telecommunications network to exchange information between TMN elements. The interconnection between the TMN and the telecommunications network is shown in Fig. 7.2. A data network is used as the network that provides communication between the NE and the OSS.

Fig. 7.2. Relationship between TMN Management System and Communication Network

TMN may use parts of the telecommunication network to support its connections.

Such parts may be:

• public and private networks, including narrowband and broadband integrated services (ISDN) networks, mobile networks, intelligent networks;
• TMN itself;
• terminal equipment of transmission systems (multiplexers, cross-connect equipment, converting equipment, etc.);
• digital and analog transmission systems (cable, fiber optic, radio, satellite, etc.);
• digital and analog switching stations;
• alarm systems;
• PBX and end user equipment.

For the network shown in Fig. 7.2, defined reference points (Fig. 7.3), in which standard protocols are specified.

Fig. 7.3 differs from the previous one by the introduction of two elements - the data transmission network inside the TMN and the element "mediator" (MD - mediator).

The introduction of a second data network indicates a more general case as compared with Fig. 7.2, when the TMN network has its own data exchange network.

The mediator (intermediary) is introduced for the physical and informational coordination of the communication network and the TMN network.

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Fig. 7.3. Reference points for interconnection of TMN system and communication network

According to the TMN concept, in fig. 7.3 it is possible to identify the elements on which the communication system is built (building blocks - building blocks):

• network element (NE);
• mediator (MD);
• workstation (WS);
• Q -adapter (at the junction points q3 and q2).

The data network is not included in the number of building blocks.

Functional architecture and its relation to the physical

The above building blocks can perform the following functions:

1. The functions of network elements (NEF - Network Element Function), which are a model of an arbitrary network element to be controlled. These include: basic telecommunications functions that provide data exchange between the user and the communication network (in the TMN specifications are not specified), and management functions that allow the network element to act as an agent.
2. System Operations Support Functions - OSF (Operations System Function) functions that provide OSS-TMN functions for processing, storing and retrieving control information. These FBs form the core of the TMN; in accordance with the hierarchy are determined by FBOSF four levels:
   • element management (OSF-NE);
   • network management (OSF-N);
   • service management (OSF-S);
   • administrative management (OSF-B).
3. Mediation Functions (MF), i.e. information exchange functions between NEF (or QAF) and OSF blocks. A single MF unit is able to connect a support system for operations with several network elements or Q adapters. In addition, the MF blocks themselves can be cascaded. Among the blocks of this class, it is worth noting specifically those that extend the functionality of OSF (for example, providing storage and filtering of control information) and NEF (in particular, converting such information from a local representation to a standard one).
4. Workstation functions that provide a user interface (WSF - Work Station Function), through which service personnel and network users interact with the control network.
5. QAF - Q -adapter functions (QAF), which are designed to interact with network elements or operation support systems that have interfaces not specified in TMN.

Each building block can perform one or more of the listed functions.

Options for the placement of these functions are shown in Table 7.2.

Table 7.2. Correspondence between functional and building blocks

Physical components	Functional blocks
	Nef	Mf	QAF	OSF	WSF
Network Element (NE)
Mediator (MD)
Q - adapter
Workstation (WS)
Data Network (DCN)
Required accommodation Possible accommodation

For the exchange between functional blocks, the reference points are defined, at which the exchange protocols between the processes shown in Fig. 2 are specified. 7.3. Each of the reference points defined above is physically implemented as a corresponding interface.

Interface f is used to connect workstations with operation support systems and intermediaries (mediators).

Interface x - for interaction of systems with systems supporting the operation of other TMN networks.

The q interfaces provide for the interaction of network elements, operation support systems, intermediaries (mediators) and Q adapters through a data network.

The q3 interface, which is assigned a central role in TMN, serves to interface with the data transmission network of the support systems for the operation, support systems for the functioning of intermediaries in Q adapters, and network elements with built-in intermediary functions.

The q _x interface is used when connecting network elements and Q adapters to an intermediary.

TMN interfaces are a formally defined set of protocols, procedures, message formats, and semantics used to transfer information using control properties within an object-oriented system. To date, the most well-developed TMN interface is q3, the details of which protocols are defined in recommendations Q.811 and Q.812.