Patent ID: 6944161

Claim:
A method for assigning data units contained in successive cells of a cell stream to sequential storage positions of successive data frames of a data frame stream, wherein each of said data frames contains a predetermined number NF of data units, and said cell stream is organized as sequential cell blocks each with a predetermined number NC 1 of first type cells including at least a sequence number field indicating the position of the cell in the cell block; and a first data portion with a first number NDU 1 of data units; and one second type cell including at least a sequence number field indicating the position of the cell in the cell block; a second data portion with a second number NDU 2 of data units; and a pointer value field including at least a data frame delimiter pointer value indicating a number PTR of sequential data units of at least the second data portion to be written to a previous data frame before data units follow to be written to a current data frame; comprising the following steps: a) receiving a second type cell, reading the sequence number and the data frame delimiter pointer value of this second type cell; b) reading from the second data portion the last NDU 2 −PTR data units and assigning them to the first NDU 2 −PTR sequential storage positions of the current frame; c) receiving further cells, reading the data units from the respective data portion of the cells, and assigning the read data units to sequential storage positions of the current frame following those at which the data units of the second data portion are stored; d) receiving a cell loss indication indicating that in a current cell block a second type cell having a data frame delimiter pointer value is missing; e) determining and memorizing the sequence number of the missing second type cell and determining and memorizing the number PTR′ of data units in the missing second type cell which still belong to the current frame on the basis of the read data frame delimiter pointer value, the sequence number of the read second type cell and the number of data units per frame; and f1) assigning a number PTR′ of dummy data units to the final sequential storage positions of the current frame; f2) assigning a number NDU 2 −PTR′ of dummy data units to the first sequential storage positions of the next frame; and f3) reading NDU 1 data units from the first type cell having the sequence number following the determined sequence number of the missing second type cell and assigning the data units to the sequential storage positions in the next frame following those of the dummy data units.