Abstract: Several nodes are connected to a ring structure by means of communication lines in a network for packet-oriented data traffic. Each node is connected to lines of the ring structure. A buffer circuit is provided between the high speed interfaces for reading a routing information on the head of a data packet. The buffer circuits are structured in such a manner that the delay time in the transit traffic is smaller than, for example, 10 .mu.s. Several users are connected at the node. A wait line circuit is provided for each user. A controller ensures the processing of the data packets in the transit, insert and extract modes.

Abstract: In digital data packets comprising a first datum from which a second datum can be unequivocally computed, e.g. an error correction value, one or a plurality of additional data can be introduced by manipulating said second datum without altering the structure of the data packet. For this purpose, one or a plurality of bits of the second datum are modified in an unequivocally reversible manner, e.g. inverted, according to the additional datum which is also digital. The recuperation of the additional data is effected by comparing comparative values which are obtained by reversing all possible combinations of additional data in a received data packet to a value which is computed from the first datum of the data packet: The presence of the corresponding combination of additional data results from the consistency of the latter with one of said comparative values. Another possibility is to limit the inquiry to a fraction of the possible combination.