Architecture, networks Scientific computing at INRETS is based upon a decentralized and evolutive architecture; thus the researchers, from their terminals, can access, independantly of their geographical localisation, the different servers and shared softwares. Each site (INRETS : Bron, Marne, Satory, Lille, Salon, Marseilles; LCPC : Paris, Nantes, Champs sur Marne) has a local Ethernet network which connects UNIX workstations as well as personal computers devoted to scientific or office applications. Communications servers also to access servers on the national and international networks (internet). Servers and services The installation of specialized servers on the network is well adapted to the needs of the researchers in various services : intensive calculus, databases, communications, archives, print-outs. Specialized servers shared by INRETS and LCPC are : a Sun Enterprise 6500 server for parallel processing (finite elements calculus, traffic forecast), a software server (statistical analysis, numerical analysis, SAS and SPSS, tools for development), a databases server with the INGRES relational environment and the TEXTO documentary environment, which hosts several important databases managed either by CIR or by the concerned research units, a communication server offering to the researchers national and international exchanges, an archive server, using different kinds of media supports, print servers, on each site,