7 TM Architectural aspects

32.1023GPPArchitectureRelease 17Telecommunication managementTS

7.1 Architectural relationship

The basic aspects of a TM architecture, which can be, considered when planning and designing a TM network are:

– The functional architecture.

– The information architecture.

– The physical architecture.

The management requirements – from the business needs – will be the base for the functional architecture, which will describe the functions that have to be achieved. The information architecture defines what information that has to be provided so the functions defined in the functional architecture can be achieved. The physical architecture has to meet both the functional architecture and the information architectures. Other constraints from realty will also have impact to the physical architecture as cost, performance, legacy systems and all preferences any operator will have on a big capital investment as a TM network.

Figure 7.1: Architectural relationship

7.2 Architectural constraints

Large software systems, such as a network management system, are a capital investment that operators cannot afford to scrap every time its requirements change. Operators are seeking cost-effective solutions to their short-term needs. All these reality-related issues are vital constraints that should be addressed in the definition of the architecture.

The standardisation of 3GPP systems will bring new and different services that will add new demands on telecommunications management. Every PLMN organisation will include different functionality depending on the role-played and the equipment used by that entity. Regulation may force some of the roles that shall be taken. The need to link systems across corporate boundaries will be a consequence of this.

The rapid evolution of new services and technologies will also put requirements on the PLMN physical management architecture to accommodate market and technology trends. To future-proof investments and continuously be able to take advantage of new technologies are important constraints to the physical architecture.

A PLMN TMN should also adopt an architecture that will achieve scalability and extensibility of systems and networks so the TMN can grow as the services expand over time. To start with a small TMN and easily be able to expand the TMN after new requirements will be important issues for most PLMN operators.

The Telecom Management Network will be just one part of the overall business of a company. System management, general security issues and development strategies can be the target for company policies. System architectures and technology choices, as well as the availability of off-the-shelf commercial systems and software components that fulfil the requirements established in the present document, may be critical to an operator’s implementation of the specified management architecture.

7.3 Interoperability

7.3.1 Introduction

The new requirement on a 3GPP system TMN will imply a focus change from network element management towards management of information "information management". Network and service providers make use of different information in several different ways which also may vary from network to network and from time to time. Basic information such as alarms is of course essential information for localising faults but may also be the key information to be able to set up a service with a service level agreement.

Numerous different interfaces can be identified in a PLMN network in the areas of network element management, network management and service management. The most important and complex of these interfaces will be standardised but many interfaces of less importance are unlikely to be fully standardised and will be up to the individual operator and vendor to develop. To adopt mainstream computing technologies, re-use widely used protocols, standards and an open system architecture will be essential to secure interworking between all physical entities in a PLMN.

Low-cost and general access to management systems information will be needed. Obviously this is the critical issue and challenging task in the heterogeneous, distributed and complex network of a PLMN.

7.3.2 Interfaces

A PLMN will consist of many different types of components based on different types of technologies. There will be access-, core-, transmission- and service node networks and many of the components have already been the targets for Telecom Management standardisation at different levels. Many of these standards will be reused and the management domain of a PLMN will thereby consist of many TMNs. The architecture of PLMN TMNs should support distributed TMNs and TMN-interworking on peer-to-peer basis.

The Telecom Management Architecture can vary greatly in scope and detail, because of scale of operation and that different organisations may take different roles in a PLMN (see clause 5). The architecture of PLMN TMNs should provide a high degree of flexibility to meet the various topological conditions as the physical distribution and the number of NEs. Flexibility is also required to allow high degree of centralisation of personnel and the administrative practices as well as allowing dispersion to administrative domains. The 3GPP Telecom Management architecture should be such that the NEs will operate in the same way, independently of the OS architecture.

Figure 7.3.2.1 illustrates the basic domains in a 3GPP system (identified in 3GPP Technical Specifications [12], [13]), related management functional areas and introduces Interface-N (Itf-N).

Figure 7.3.2.1: Overview of 3GPP Telecom Management Domains and Itf-N

Itf-N between the NE OSFs and NM/SM OSFs could be used by the network- and service management systems to transfer management messages, notifications and service management requests via the NE OSF to the Network Elements (NEs).

This interface shall be open and the information models standardised.

Telecom management interfaces may be considered from two perspectives:

1) the management information model;

2) the management information exchange.

The management information models will be standardised in other 3GPP documents but the management information exchange will be further described in this architectural standard.

The management task will vary greatly between different network elements in a PLMN. Some NEs are of high complexity e.g. a RNC, while others such as border gateways is of less complexity. Different application protocols can be chosen to best suite the management requirements of the different Network Elements and the technology used.

Application protocols can be categorised out of many capabilities as:

– Functionality;

– Implementation complexity;

– Processor requirements;

– Cost efficiency;

– Market acceptance, availability of "off the shelf commercial systems and software".

For each Telecom Management interface that will be standardised by 3GPP at least one of the accepted protocols will be recommended. Accepted application protocols (e.g. SNMP, CORBA IIOP) are defined in TS 32.101 [2], annex A.

Figure 7.3.2.2 below illustrates the basic domains in a 3GPP system (identified in 3GPP Technical Specifications [12], [13]), related management functional areas and introduces Interface-P (Itf-P2P).

Figure 7.3.2.2: Overview of 3GPP Telecom Management Domains and Itf-P2P

Itf-P2P between two NE OSFs (or NE Management as shown in the above figure) could be used to transfer network management information such as network configuration management information

The information model and the protocols used shall be those defined for Itf-P2P. They are listed in Annex E of [2].

7.3.3 Entities of a 3GPP system

To provide the mobile service as defined in a 3GPP system, some specific functions are introduced [12]. These functional entities can be implemented in different physical equipments or gathered. In any case, exchanges of data occur between these entities and from the Telecom Management perspective they can all normally be treated as network elements. The basic telecom management functional areas such as fault management, configuration management, performance management and security management are all applicable to these entities. As such they are all the targets for 3GPP Telecom Management technical Specifications.

As discussed in clause 5, there will be many possible ways to build a 3GPP system and thereby many possible architectures of a mobile system. The entities presented in figure 7.3 should be treated as the fundamental building blocks of any possible implementation of a 3GPP system.

Figure 7.3.3.1: Examples of entities of the mobile system to be managed

In figure 7.3.3.2 the prime domains for the standardisation effort of 3GPP Telecom Management are shown as shaded.

Figure 7.3.3.2: High level 3GPP system Network architecture

7.3.4 Open systems approach

Even in the second generation of mobile radio networks the operators have to cope with heterogeneous environments in many different ways. No single vendor is likely to deliver all the management systems needed for a mobile operator.

The many different types of network elements, some with very high management complexity such as an exchange and some less complex such as a repeater system, are generally supported with unique vendor specific management systems with very low interoperability. Duplicated TMN applications is another obvious reality of this generation of management systems. This will be further discussed under clause 9 (TMN Applications).

The 3GPP requirements call for open systems that can be supported by the marketplace, rather than being supported by a single (or limited) set of suppliers, due to the unique aspects of the design chosen. Open systems architectures are achieved by having the design focus on commonly used and widely supported interface standards. This should ensure costs and quality that are controlled by the forces of competition in the marketplace.

The open systems approach is a technical and business strategy to:

– Choose commercially supported specifications and standards for selected system interfaces.

– Build systems based on modular hardware and software design.

Selection of commercial specifications and standards in the Open systems approach should be based on:

– Those adopted by industry consensus based standards bodies or de facto standards (those successful in the market place).

– Market research that evaluates the short and long term availability of products.

– Trade-offs of performance.

– Supportability and upgrade potential within defined cost constraint.

– Allowance for continued access to technological innovation supported by many customers and a broad industrial base.

7.3.5 Level of openness

The level the interfaces conform to open standards is critical for the overall behaviour. A low level of openness will severely impact on long-term supportability, interoperability, development lead-time, and lifecycle cost and overall performance.

Interfaces are expensive parts in a TMN and interfaces with low level of openness severely impact on development lead-time for the introduction of any system, application component or service. Easy implementation (plug & play) is a requirement for TMN physical entities and requires a high the level of openness.

7.3.6 Closed interfaces

Many second-generation mobile network physical management entities have vendor controlled system/subsystem boundary descriptions that are not disclosed to the public or are unique to this single supplier – closed interfaces.

Such interfaces will not fulfil the basic requirements of a 3G TMN. Closed interfaces can only be used as internal interfaces where no information what so ever has to be shared to other physical management entities.

7.4 Data communication networks

Within a TMN, the necessary physical connection (e.g. circuit-switched or packet-switched) may be offered by communication paths constructed with all kinds of network components, e.g. dedicated lines, packet-switched data network, ISDN, common channel signalling network, public-switched telephone network, local area networks, terminal controllers, etc. In the extreme case the communication path provides for full connectivity, i.e. each attached system can be physically connected to all others.

The TMN should be designed such that it has the capability to interface with several types of communications paths, to ensure that a framework is provided which is flexible enough to allow the most efficient communications:

– between NE and other elements within the TMN;

– between WS and other elements within the TMN;

– between elements within the TMN;

– between TMNs;

– between TMNs and enterprise.

In this case the term efficiency relates to the cost, reliability and maintainability of the data transported.

Two aspects impact costs. The first is the actual cost to transport data across the network between the TMN and the NE. The second aspect is the design of the interface including the selection of the appropriate communications protocol.

Whatever standardised protocol suite at the networking level that is capable of meeting the functional and operational requirements (including the network addressing aspects) of the Logical and Application Protocol levels of a given 3GPP management interface, is a valid Networking Protocol for that interface.

A number of requirements must be met by the Networking Protocol, as follows:

– Capability to run over all supported bearers (leased lines, X.25, ATM, Frame Relay, …)

– Support of existing transport protocols and their applications, such as OSI, TCP/IP family, etc.

– Widely available, cheap and reliable.

The Internet Protocol (IP) is a Networking Protocol that ideally supports these requirements. IP also adds flexibility to how management connectivity is achieved when networks are rolled out, by offering various implementation choices. For instance, these may take the form of:

– Dedicated management intranets.

– Separation from or integration into an operator’s enterprise network.

– Utilisation, in one-way or another, of capacities of the public Internet and its applications or other resources.

7.5 New technologies

Meeting application requirements in the most affordable manner together with development lead-time are important issues identified in early 3GPP management standardisation work. But the TMN functional, information and physical architectures should also keep pace with the introduction of new technologies, services and evolving network infrastructures. Technology is advancing so rapidly today that this should be a fundamental part of the physical architecture – to be able to easily adopt new important technologies.

A 3GPP system will need to incorporate new successful technologies from the IT-world. Today distributed computing implementations have matured to a point where the goals of TMN can be realised using commonly available technologies for a reasonable cost.

Widely accepted open standards and new IT-technologies will be indispensable to fulfil the challenging managing requirements of a 3GPP system.

New technologies in the IT business such as generic application components together with distributed processing technology are new important drivers upon application design of management systems. The possibility to purchase functional components from the open market are of great importance from many aspects such as cost-efficiency and time-to-market.