| 摘要 |
The invention describes a method for transmitting data packets over a packet switching network with widely varying link speeds. The switches of the network maintain a common time reference (CTR). Each switch along a route from a source to a destination forwards data packets in periodic time frames (TFs) of a plurality of durations that are predefined using the CTR. The time frame duration can be longer than the time duration required for transmitting a data packet, in which case the exact position of a packet in the time interval is not predetermined. In accordance with the present invention, different time frame intervals: TF1, TF2, and so on are used for forwarding over links with different capacities. Employing different time frame intervals is useful in heterogeneous networks with widely varying link speeds, since the number of bytes that can be transmitted during one time frame of one of, for example, 500/125/62.5/12.5 microseconds changes according to the link capacity and various other system parameters and considerations, such as, maximum data packet size. When the transmission of a data packet cannot be completed before the beginning of the next time frame, a time-driven preemption priority can be used in order to ensure the timely transmission of real-time data packet before "best effort" data packets. When the transmission of a data packet cannot be completed in its current time frame the transmission of this data packet can continue in the following time frames.
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