| 摘要 |
<p>In a data packet network, packets are transferred from input ports to output ports. Packet transfers can require time periods of different lengths because data packets, as they are transported in the network, pass through units where they are subjected to processing. In each input port, a list is established of current combinations of source addresses and destination addresses for the data packets that have arrived at the input port. The list includes the current sequential number for data packets having this combination. This list is restricted or limited so that it includes only a small number of records. When a data packet is received by an input port, and the source address and destination address of the dam packet are not already in the list, the record in the list that has been inactive for the longest time period is overwritten, thereby erasing the corresponding sequential number. When a message having the same source address and destination address arrives again, the sequential number is restarted. At the same time, a flag is set in the packet, indicating the restart. Further, those records that have been inactive during some predetermined time period are removed from the list. Also, in the output port there is a similar list that is reduced to avoid long search times. If a record in the list in an output port has been inactive for a sufficiently long time, it can be removed from the list, since then the corresponding record is already removed in the list in the input port.</p> |
