Abstract: Apparatus for monitoring a flow of ATM cells in which a measured value is calculated in all cases. A `leaky bucket` mechanism known for this purpose has too few degrees of freedom to be able to monitor the flow of cells accurately enough for it to be possible to deduce from cell flow variations whether a (temporary) cell rate increase is the consequence of an unavoidable variation induced by the transmission system or of an unduly high cell rate (which is in fact avoidable) on the part of the system users. The operation of the apparatus can be adjusted better to the cell flow characteristics if the measured value (CV.sub.n) is a function of a previously calculated reference arrival time (RAT.sub.n) and the actual arrival time (AT.sub.n) of the arriving cell. The reference arrival time is, in turn, a function of the reference arrival times (RAT.sub.n-p, RAT.sub.n-q, . . . ) of one or more preceding cells (n-p, n-q, . . . ) and of the actual arrival times (AT.sub.n-p, AT.sub.n-q, . . .

Abstract: Method of transferring, via a transmission medium comprising asynchronously time-division-multiplexed transmission channels, a data stream comprised of data cells. A monitoring apparatus at the beginning of the transmission medium stores, for each transmission channel, a counter position (variable) which, when a data cell arrives at the monitoring apparatus, is amended as a function of time which has elapsed from a reference time instant. Depending on the amended counter position and a threshold value, the data cell is granted or refused access to the downstream transmission medium. The reference time instant is determined by the monitoring apparatus completely or at least partly, independent of the time instant of the appearance of the data cells. A first option provides for the monitoring apparatus to shift the reference time instant in time in accordance with a fixed sequence schedule. According to a second option, the reference time instant is shifted in time in accordance with a fixed time schedule.

Abstract: Packets transmitted in an automatic packet transmission system each have an information part and a header part. The heater contains virtual channel information (vci), identifying the virtual transmission channel and/or the group of virtual transmission channels via which the packet is being transmitted. The transmitted system at a junction point comprises 94 access control system including a counter-and-threshold access control device (3) controlling a switch (2) for granting or refusing packets access to the downstream part of the transmission system, depending on the arrival rate of incoming of packets of the respective packet types identified by their virtual channel information. An error reporting device (4) records per vci the arrival rate of packets which are refused access downstream when a first threshold arrival rate is exceeded. Arrival rates and arrival rate thresholds are measured by a "leaky bucket" method for each packet type.

Abstract: The flow of data cells through a transmission medium with a plurality of virtual, asynchronously time-divided transmission channels is protected against excessive crowding of data cells in any channel, or of any customer, by means of a counter for each channel and the recording of the time or arrival of data cells in each channel. The counter is advanced by a predetermined amount at the arrival of each data cell and in the same operation is decreased by a value which is a function of the length of time between the moment of arrival of that data cell and the moment of arrival of a preceding data cell with the same channel designation. The state of the counter is also compared with a threshold value which, if equalled or exceeded results in the data cell not being switched through a switch controlled by the comparison, while in other cases the data cell is let through to the downstream portion of the channel.