Patent ID: 6594267
Filing Date: 2003-07-15
Classification: H04L

Abstract:
An AAL2 packet exchange device which is placed in front of an ATM switch for executing CPS packet re-multiplexing into ATM cells, wherein the AAL2 packet exchange device extracts CPS-PDUs (Common Part Sublayer-Protocol Data Units) from ATM cells which are supplied from input ATM lines, extracts CPS packets from the CPS-PDUs, alters CIDs (Channel IDentifiers) of the CPS packets if necessary so that CID collision will not occur between CPS packets supplied from different sources to be outputted to the same output ATM connection, multiplexes the CPS packets to be outputted to the same output ATM connection in ATM cells of the same output ATM connection, and thereby realizes re-multiplexing of CPS packets extracted from ATM cells supplied from different sources into the same ATM connection without the CID collision, said AAL2 packet exchange device comprising:a selector means for selecting ATM cells containing CPS-PDUs and ATM cells not containing CPS-PDUs from ATM cells supplied from the input ATM lines, outputting the ATM cells not containing CPS-PDUs untouched, and extracting the CPS-PDUs from the ATM cells containing CPS-PDUs; a path setting table means for storing a table indicating each correspondence between a first internal address for discriminating between input ATM connections, an input CID, a second internal address for discriminating between output ATM connections, and an output CID; a first memory means for storing the CPS-PDUs extracted by the selector means and the first internal addresses concerning the CPS-PDUs; a CPS-PDU processing means for extracting CPS packets from the CPS-PDU which has been stored in the first memory means, storing the front part of a CPS packet if the CPS packet has been split across two CPS-PDUs, and regenerating the CPS packet when the rear part of the CPS packet is supplied by adding the rear part to the front part of the CPS packet which has been stored therein; a CPS packet processing means for obtaining the second internal address and the output CID concerning each CPS packet extracted or regenerated by the CPS-PDU processing means by referring to the path setting table means using the first internal address and the CID (input CID) concerning the CPS packet, updating the CID (input CID) of each CPS packet into the output CID, updating HEC (Header Error Control) information of the CPS packet, and outputting the CPS packet and the second internal address concerning the CPS packet; a second memory means for storing the CPS packets and the second internal addresses concerning the CPS packets outputted by the CPS packet processing means; a CPS-PDU generation means for reading out the CPS packets and the second internal addresses concerning the CPS packets from the second memory means, multiplexing CPS packets corresponding to the same second internal address into a CPS-PDU, and outputting the CPS-PDU; an ATM cell generation means for filling the CPS-PDU supplied from the CPS-PDU generation means in an ATM cell and outputting the ATM cell to one of its output lines according to information obtained from the path setting table means, and meanwhile outputting an idle ATM cell to each output line that has no ATM cell to be outputted thereto; and a multiplexing means for multiplexing the ATM cells not containing CPS-PDUs outputted by the selector means and the ATM cells outputted by the ATM cell generation means, and outputting the multiplexed ATM cells to its output lines.