s can manage both tele- and data-centric services, capacity can be saved for other data traffic for more than 30 years, supported by an impressing development of modems. ATM has offered efficient multi-service use of the transport capacity. See Figures 3.11 and 3.12. In Figure 3.12, the upper curve on the left-hand side represents data traf- fic and the lower curve represents voice traffic. Both curves and the sum of the two curves appear on the right-hand side. In this situation we want to use the investments as much as possible. Further we need an adaptation between the purpose-built networks and a service/application layer, which is independent of available access/bearer networks. Roughly we get the traditional voice-centric and data-centric networks converging with service/application-oriented part, offering information retrieval and streaming services. 3.4.3 TRANSITION FEATURE 3 The Convergence Glue: IP From a traffic point of view the original interactive and symmetric voice-dominated com- munication is complemented with, and in fact overtaken by, a client-server IP-based asymmetric traffic pattern. See Figure 3.13. This bursty pattern usually implies more traffic from the server than from the client. Behind the server-generated traffic one can find the media industry and other parties in the IT society as content providers. The various ways Networks and Technologies Server Portals Client Client + modem Service provider Frame relay (ATM core) Data-centric Tele-centric Figure 3.13 The converging glue: IP, service providers and (often) portals. The ATM core is not compulsory, but offers high quality to the IP traffic to deliver content 'infotainment' are usually called applications with WWW/HTTP as the first 'killer application'. Accessibility to applications from any end user independently of the existing type of access media connection is a main driver for the network evolution. Except for client-server relationships there are also peer-to-peer relationships, such as Napster downloads. This traffic pushes t