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Introduction into TMN
OverviewITU-T (formerly called CCITT) has defined a reference architecture for management of a network called 'Telecommunications Management Network', or 'TMN' for short. The prime purpose of TMN is 'the management of the network as a resource in order to deliver service', that is: exploit the network.
[M.3010] Management of a telecommunications environment is an information processing application. Because the environment being managed is distributed, network management is a distributed application. This involves the exchange of management information between management processes for the purpose of monitoring and controlling the various physical and logical networking resources (switching and transmission resources).
The name Telecommunication Management Network reflects the point that for managing a network you need a network to reach all the parts and the management is basically distributed too. This management network should be managed as well, so TMN should include 'self management'. Management in this context consists of all actions to operate the network. It includes activation/cessation of a service for a customer, signalling of faults and support for maintenance on hardware and software.
The leading recommendation is M.3010; it defines the TMN architecture. This architecture is refined in other recommendations. It must be said that these recommendations rely heavily on recommendations for management of Open Systems Interconnection (OSI). Also these definitions are on-going, that is, not all required recommendations exist, and the exiting ones are often not complete and subject to change.
First we're going to explore telecom, its characteristics and services, the driving forces and the issues.
Basically, telecommunications comprises all sorts of remote communication. Ignoring the smoke-signals and Chappe semaphores, 'modern' telecommunications started with the upcoming of electricity: the telegraph. The most popular form nowadays is telephony, i.e. the voice service, and internet, i.e. the IP data service. There are many other services like fax, all kinds of data communications, and some upcoming forms using video. There are also additional features, like for voice service 'call forwarding', 'calling line identification', 'freephone', etc. What they have in common is the geographic diversity.
For the application of a service, it is essential that they are compatible at both ends; for widespread use this means global standardisation. There is a long-standing relationship between telecommunications and standardisation.
Apart from the basic interconnection services provides by telecommunications, there are all kinds of additional services provided remotely using telecom. They are called Value Added Services (VAS). VAS can be provided by the network operator or by a third party. VAS may be implemented using so called Intelligent Networks (IN) features.
These services provide a value-add to the basic service, and as they are not subject to the strict regulations like the basic services, may provide substantial revenues.
[M.3010] Value Added Services (VAS) are services provided in addition to the basic services available in or through a network. VAS may be supplied by network operators or by additional VAS providers. It is not possible to permanently split services between basic and value added, as VAS can over a period of time become basic. Also, VAS and the split between basic and VAS may be subject to local regulations.
I.e. VAS can be provided by the telecom operator or a third party; the separation between network operator and VAS provider is not always clear for the VAS user.
Examples of VAS: call forwarding, answering service, voice mailbox, services provided through special numbers of the 800-type.
A common model for basic services versus added services with some examples is:
| VAS | Supplementary services | 800-numbers, DDI, CLIP/CLIR, ... | VOD, ... | Host DB |
|---|---|---|---|---|
| Basic | Tele-services | Voice, Fax, X25, Data | Voice, Videophone, ... | PVC, SVC, CUG |
| Bearer services | NB-ISDN: BRA, PRA | BB-ISDN: CBR, VBR, ... | X25 |
Special problems with VAS is the distinct implementation in connected networks (i.e. the VAS is not sufficiently standard to allow interworking over networks; ETSI is working on this), and the interaction between various VASes {feature interaction is a nightmare; a straightforward example is Call Forwarding and Calling Line Identification}.
The success of telephony is its cheap, easy to use, widespread application, and therefore its global reach. Success in telecom is measured by the reach of its use (span and penetration), service palette and ultimately of course profit.
Most telecom applications, and certainly the modern ones, are real-time. By nature, telecom is a geographically distributed application. When successful it means massive parallel usage, in particular of shared network resources. Operation and maintenance of such dispersed applications are very complex.
Widespread application requires considerable investments in equipment and infrastructure (cabling the country), favouring large companies and effectively growing to monopolies {economy of scale; this might not be valid that much anymore}. Also, most governments consider a good telecom infrastructure of strategic importance; this led to government controlled monopolies: PTTs. The large infrastructure and the inter-operability required for global use led to stringent standardisation.
Telecom uses simple principles. However, to achieve sufficient performance and to be cost effective, implementation is often hi-tech. Automation has been a key factor 'avant la lettre' (the first computer applications includes telecom). In the past, research and development were vital for success.
Availability of telecom has become essential, not only for day-to-day business but all kinds of services depend on telecom to be always in working order; emergency services –in particular during disasters– rely on it. Storms, fire, power outage, it doesn't matter: telecom should work ! Requirements for reliability are very high, and the solutions to achieve this in a non-perfect world are usually complex. Combined with real-time and distributed application, telecom systems must be extremely complex.
Due to the deregulation and the technological advances (see below), the telecom world is changing very fast. It is still growing, and will become the world's largest industry shortly.
So, characteristics of telecom are:
'Everybody with a 5 year business plan in telecom has no idea what is going on' — R. Allen/AT&T.
Technology:
Technology is not the driver for new services ! But as technological advances makes applications available at lower costs, it paves the way for new and/or cheaper services. The big question is which services will be really successful.
Legislation:
Incumbents (i.e. the existing PTTs) must be prevented from crushing new players, and new players must be prevented from merely skimming the cream and choosing to provide only to the most profitable segments of the market — the right regulatory balance is essential.
Customer expectancy is getting more important in a competitive environment:
With the increased competition, operators need to get customer-oriented. And that is not easy: 'Customers don't want a wide range of choices; they want what they want, and at mass production prices'. Also, (ex-monopoly) operators are weak in marketing; they can use the support from suppliers with experience in a particular area.
Due to competition, prices for telecom services will go down. Operators are getting extreme competitive pressure and are looking for new sources of income.
As the profit on bearer services will be marginal, operators will concentrate on business customers (modest investments, good use = considerable revenues), Value Added Services (good margins) and new/innovative services available with Intelligent Networks (to win over new customers and exploit high margin services).
Success depends upon how quickly the ex-monopolies can copy the new entrant's innovative ideas which win over customers, versus how quickly the new entrant can achieve the critical mass necessary to compete effectively.
On the other hand: customer awareness changes very slow; see fax, mobile (both exist since the 1940's), ISDN…
At the same time the level of service (customer care processes) has to improve an order of magnitude, while the operational costs decrease significantly. This apparent contradiction can only be solved by automation.
In the past, telecom had a tremendous technology push (hi-tech); with sufficient technology available and in a competitive environment, it has changed to market-pull (services). Telecommunications (bearer services) is becoming a commodity market. Competition will be on cost and quality, with customer care as decisive factor. 'Time to market' is vital for market share and profit.
As intelligence becomes cheaper, it moves to the edge of the network (i.e. to customer equipment; reduced need for centralised intelligence); the network becomes more and more a fast and efficient broadband transport mechanism.
By incorporating new features in terminal equipment (most likely new software), new services can be deployed very fast for every customer who needs it.
Intelligence in the network is virtually concentrated using 'Intelligent Networks' (IN) concepts, and used for functionality not possible in customer equipment like location transparency.
This trend enables fast introduction of features with minimal standardisation problems and without cost overhead.
Conclusions:
In the past, operators ordered equipment: components (boards) and systems (exchanges); now they order complete networks (e.g. SDH). In future operators will order services ! They don't want to bother setting up management systems; they need fully operable solutions: 'time to market' is profit.
As operators are facing decreasing market shares, lower prices and increased demands for service quality, they experience extreme competitive pressure. They have to decrease network costs, and the operational cost constitutes the major part.
A simple example: when it can be avoided to enter data redundantly (i.e. by integration), operations are faster and less error-prone. Less typing will at least save 10 seconds operator time on a transaction. When doing 1 million transactions, this amounts to more than 2 person years !
Network Management systems are to support operators in their activities. It is not a large monolithic application, but a collection of (network) Operations Support Systems (OSS), each supporting one or more particular operator activities.
However, one must keep in mind that Operation Support Systems are only to support the activities of operators. If these activities are poorly organised, OSSes will only provide marginal benefits. I.e. to increase the service level considerably, the operator will have to change his organisation first: 'business process re-engineering'. After re-engineering, OSSes should support the new processes.
An example (by a large telecom operator):
Provisioning of a 2Mb/s leased lines took 1 month. It comprised 12 hours actual work and involved 13 Information Systems. {Obviously it involved many departments with a lot of internal work orders. Most time was lost with work order transfer and queuing. Coupling the 13 information systems would also not be straightforward.}
Now, after business process re-engineering and support by OSSes, it takes 2 days !
Network Management enables:
Effective operation of a network is only possible by using management systems; NM is vital for operator competitiveness. In the future we probably can't imagine how we ever could have lived without Network Management.
First, it is Network Management, so you are supposed to own a network. But if you are operating as a (network) service provider, you may want parts only. Let us look at some cases:
[M.3400] A TMN is intended to support a wide variety of management functions which cover the planning of operations, administration, maintenance and provisioning of telecommunication networks and services.
I.e. it is not pure network management, but explicitly includes management of services.
Issues for Network Management:
There will always be multi-vendor and multi-technology. Every large network is a patchwork, and it won't get any better.
The multitude of interfaces clearly indicates that integration is a major problem. Standards should help here, but are typically two years behind competitive requirements.
The other major problem is the amount of data and services to be handled by the TMN. The normal solution for this is 'divide and conquer' (which increases the number of interfaces hence the standardisation problem); the ITU pursues this in various ways:
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