Abstract: A shaper (1) in a stream of data packets provides for compliance with the agreements about the packet traffic of each virtual connection. It contains means (11) for the intermediate storage and read-out of data packets and for extracting the packet clock, furthermore a control (12) which reads the packets of the different connections into the data stream at the right time. The selection of the data packet takes place on the basis of a rank which is established for each data packet located at the front of the virtual waiting line of the individual connection. With each packet clock the rank is incremented in accordance with the agreed bandwidth for this connection; thus, for each clock a new calculation for the highest two connections for which a data packet advances again to the head of the virtual waiting line, is sufficient. Two processing units (21, 24) are provided.

Abstract: A generic cell rate monitoring algorithm (GCRA) which is implemented in an ATM network element must be tested during operation. The method uses a second GCRA of the same kind which is synchronized with the first one, and a conformity test is carried out by comparing the results of both GCRAs. The synchronization is preferred when both GCRAs are in a regeneration state. This is artificially produced during operation of the GCRA to be tested by temporarily changing a parameter of the agreement in such a way, that a contract violation can no longer occur. The time of reaching the regeneration state can be limited by special steps of the method. An apparatus for carrying out the method (30) comprises a conformity decision unit (20), which counts arriving cells and compares counter positions, an implementation of the second GCRA (14) and a circuit (13) for synchronization, together with a return line (15) to an insertion circuit (16) for the cell stream in the line (1).

Abstract: In digital transmission systems, adapted data units travel at a high throughput rate over large parts as a stream of fixed length data packets, called cells in this instance. The present method permits the measurement of characteristic magnitudes of the cell stream with respect to the respective individual connection to which they belong. It is based on storing from each arriving cell the identification data of the individual connection to which it is allocated, including its relative position in the cell stream. The memory is interrogated during a cell cycle time. A selection is made about which memory spaces within a defined area contain a predetermined identification data belonging to an individual connection. As a function of the selected memory spaces, the determined result, together with the magnitude and the position of the interrogated area, provides a decisive statement of the measured value.

Abstract: From a stream of digital data units (10), which exhibits gaps as a result of parameter monitoring, the number of missing data units must be determined and the response time of the parameter monitoring must be estimated at the place of determination for non-conforming data units (15, 16, 17; 21). The method is based on using the identification number (12, 13, . . . ), which is carried by the data unit (10), to detect the gaps. A starting time (L12) is established with the arrival of a first conforming data unit, which is continuously updated as long as no gap occurs. After a gap is detected, the updated time (L14) of the last conforming data unit serves as the lower barrier (L[1]) of the response time, that of the first conforming data unit (18) after the gap as the upper barrier (U[1]) of the response time. The number of missing data units can be derived from the gap in the identification numbers. The method can be immediately continued, so that many values can be stored and used for a statistical evaluation.

Abstract: A switching unit (1) for the switching through of different types of digital data in the asynchronous transfer mode, a so-called ATM-switch, is to be tested whether it is able to overcome a specific load. The installation provides for the feedback (4) from outputs (2) to inputs (3) of baseload cells, which are fed by a generator (5) to an input (35), and constantly circulate because of their routing information. The generator (5) also emits test cells to the input (35). A chooser or discriminator (6) is connected to a measuring output (21) and feeds it back (41) to an input (31). The chooser (6) is able to read, change, copy or suppress certain contents of data cells. It routs the cells back and/or through a second output and an analyzer (7), which evaluates them statistically. Load testing of such a switching unit, whether it can handle a specific load, may cause instabilities in the switch, such as uncontrolled cell loss, congestion, routing errors and the like.