Abstract: A method and apparatus for admitting packets into the buffer of an attachment of a communications adapter. More specifically, a discard bit is maintained in a table of the attachment to indicate whether a cell of a packet was previously discarded because of a buffer full condition. All subsequently received cells of a packet are automatically discarded if the discard bit is in the state indicating that a cell was previously discarded because the buffer was full.

Abstract: A method of scheduling requests from N.sup.2 input queues to N outputs is applied to an N.times.N switch with each of the N input ports having N input queues, each of the N input queues for each of the N input ports corresponding to one of the N output ports. The method uses a request matrix with each row representing an input and each column representing an output. A bit in a given row and column of the matrix thus represents a request from a corresponding input port for connection to a corresponding output port. Diagonal service patterns are used to overlay the request matrix to determine which requests are to be serviced. A sequence of diagonal service patterns for each of K time slots is used in such a manner that a fairer and yet still computationally simple scheduler provides guaranteed service within the 2N-1 time slots.