Abstract: The spacer has a cell memory, means for allocating a theoretical emission time to each cell, means of control for managing the cell memory, with the aid of an associated pointer memory, in such a way that the cell memory includes, for each virtual connection for which it contains cells, a list of locations where these cells are stored in first-in first-out mode, sorting means for ordering data elements each comprising a virtual connection identity and a sort key consisting of the theoretical time of emission of the cell contained in the start of list relating to said virtual connection, and for selecting at least one data element having a minimum sort key. Each cell emitted is contained in the start of list relating to a virtual connection identified in a data element selected by the sorting means.

Abstract: In order to sort data elements each including a sort key, storage means are organized according to a binary tree of 2n−1 nodes which are each able to contain an element and are distributed in n successive stages numbered from 0 to n−1, stage q containing nodes 2q to 2q+1−1. The elements are dispersed within the tree in such a way that each element contained in a node i has a smaller sort key than those of the elements contained in nodes 2i and 2i+1. The trees managed by m successive controllers each associated with a stage or with several consecutive stages of the tree (2≦m≦n), with n−1 interface registers between successive stages, among which those located between the controllers are pipeline registers allowing parallel working of the controllers so as to modify the contents of the tree upon exchange or insertion command propagated from stage 0 to stage n−1.