Concept No. 1: using the same packet network for the everyday transmission of information (voice, data and video) and all other services

ATM makes it possible to provide a quality of service, a QoS to which the France Telecom client has become largely accustomed. However, IP, from its end, even if it has become a standard at an application level, does not know how to guarantee quality of service. IPV6 solves the problems of useful addresses and security but the quality of service depends on technologies still in their experimental stages.

The result: the two technologies are currently combined. ATM is used at the transmission level (level 2 of the network layer). ATM is still the basic technology for ADSL. But the network will have to evolve towards IP, which is used in applications.

Concept No. 2: externalising and distributing intelligence

Today, the telephone switch includes all the layers: transmission with the switching matrix, a control component that makes it possible to control connections on this matrix and the service portion that is often included in the control. All of this is found in the same machine. The semaphore network makes it possible to send information, signals and the command information of the service network.

In the NGN architecture, the connection matrix is spread out over the entire packet network. The idea is to isolate the transmission layer by taking out the control, as shown in the diagram. A call server pilots the gateways, which are found at the transmission level. It only ensures the connection from one point to another. These access gateways are the link between the new technologies and what currently exists. They are the interface between the telephone world and the call server that pilots them. For a traditional operator, the problems of inter-operability with existing networks must be taken into account.

Another advantage is that call servers may be grouped in hosting sites as they are not linked to the connection matrix. Operating costs are thus minimised. The operator can also put specialised teams in place on these servers and guarantee an excellent quality of service. He thus solves a human resource problem: today, the people who take care of a switch must have wide ranging skills because technologies used are more and more state of the art.

At the control layer level, what involves establishing a pathway and the application part are also separated. The latter is brought back into the application platforms with standardised interfaces that are called APIs. With these APIs, the market is opened to new companies, which will design the basic components that will allow an operator to build his own applications rapidly.

Furthermore, the network has well-identified interfaces among the different layers available. It is thus possible to protect the investments in each of the layers, regardless of modifications made in the other layers of the network.

Concept No. 3: an optical transmission network

Basic technologies are evolving. For example, we use wavelength multiplexing and we are heading towards an all-optical network core. Today, we are still primarily using the existing infrastructure, or copper, for the entire periphery, which represents 80% of the investment. But we will have to progress, as applications require higher and higher throughputs and the copper network's limits will one day be reached. This migration has in fact started at the level of companies, which already have direct accesses via optical fibres.

Concept No. 4: segmenting the market through open interfaces

We have defined standard interfaces among the various layers. At the level of equipment, this makes it possible to take advantage in each of the areas and to have heterogeneous networks, something which is currently difficult to do.