Koninklijke Ptt Nederland N.v.

Gerrit J Van Loo

Martin Klaas De Lange

Dick Brandt

Jean Paul Boly

Gerrit Roelofsen

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

In a system for de-/encoding data using (de)coding devices at either end of a transmission channel, the data sometimes comprise additional synchronisation information which is used to reduce the effect of faults in the transmission channel. If this synchronisation information is not already present, it is impossible in certain cases to add such information. The invention provides a system which, regardless of the presence of additional synchronisation information, is able to reduce the effect of faults. For this purpose, each (de)coding device is provided with means for comparing sequences of encoded data with at least one predetermined code word and for setting the associated coding device to a reset state in the event of equality. Because the predetermined code word repeats statistically in the encoded data, a fault adversely affects the decoding for not more than one time interval.

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Delft, Netherlands

Gerrit J Van Loo