Koninklijke Ptt Nederland N.v.

Dick Brandt

Gerrit J Van Loo

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. When the arrival rate of packets which are refused downstream access exceeds a second threshold value the error reporting device prevents excessive processing of access refusals in overloaded virtual channels and sends an error message for attracting the attention of supervisors or users of the transmission system.

Transmission system with recording of untransmitted packets

Method and device for monitoring a downstream transmission medium which comprises a multiplicity of virtual, asynchronously time-shared transmission channels via which a data flow can be transmitted. The data flow is composed of data cells comprising a control word group (header) and an information word group. The header is read out in a monitoring device. On the arrival of a data cell, a number of variables is incremented and processed to produce a corresponding number of assessment signals. Each data cell header gives an indication of those variables which have to be incremented and processed, and of the mutation (incremention) and assessment algorithms to be used in doing so. Furthermore, one or more of the assessment signals are processed in accordance with a combination algorithm, deduced from the data cell header too, to form a control signal.

Method for controlling a flow of data cells into a plurality of

For monitoring a transmission system comprising a number of asynchronously operating channels through which data cells can be transmitted, variable values are stored which, on arrival of a data cell, are altered by an alteration algorithm in accordance with data cell traffic and are then processed by an evaluation algorithm to produce an evaluation signal. Such evaluation signals are processed by a combination algorithm to produce a control signal. A data cell is or is not, transmitted, depending on the value of the control signal. Quality classes are assigned to the data cells and for each quality class a first variable value is stored, which is altered by a first alteration algorithm when a data cell arrives at a first location and is processed by a first evaluation algorithm to produce a first evaluation signal. The channels are divided into groups, each comprising those channels which use a particular potential congestion point in the transmission system. For each group of channels a second variable value is stored, which is altered by a second alteration algorithm when a data cell arrives at a second location and is then processed by a second evaluation algorithm to produce a second evaluation signal. Depending on the value of the second evaluation signal and depending on the value of the respective quality class, the first alteration algorithm or the first evaluation algorithm or both are so controlled that the number of data cells transmitted is reduced and this the more for data cells of lower the quality classes.

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Voorburg, Netherlands

Dick Brandt