Traffic in ATM networks can be described by numerous parameters. On a per session basis, one may use peak rate, average rate, sustainable rate, average burst duration, average silence duration, and others. In a longer time scale, parameters like the average and peakedness of connection request arrivals, the average and variance of session holding times, and so on are proposed. Theoretically, users should provide the former parameters and network operators the latter. In reality, however, few users can be expected to provide all sorts of statistical information about their traffic in advance, and operators do not have enough experience to prepare traffic forecasts for new services and applications. Moreover, even if the information could be provided, the lack of simple yet valid traffic models for ATM networks means that it is far from clear how it should be used. Realising that ATM networks, which are already being built, at least for the next few years will have to operate under these uncertain conditions, we focus on robust and forgiving strategies for traffic management. The idea is to use only little information about offered traffics and then dynamically control resource allocations, so as to provide acceptable quality of service combined with high utilisation. We give some draft proposals in this direction and point at some open research issues.