Connectionless servers may be used to provide connectionless data services in ATM wide area networks. However, their performance might be a critical point, since, like w i t h a n y other server, undersized connectionless servers might become bottlenecks in the network. This paper aims at providing some insight on this issue. We present the design and the implementation of a portable SMDS (Switched Multi-megabits Data Service) server, and discusses performance related aspects of a SMDS server-based connectionless network implemented in our laboratory. W e conclude on the interest and perspectives of this kind of network architecture.