Patent ID: 8774063

Claim:
A method of transferring data packets across a multi-path network having a plurality of network elements interconnected by network links, the method comprising for each data packet arriving at an egress port of the multi-path network via a path having one or more network links, issuing a delivery acknowledgement from the egress port concerned and transmitting the delivery acknowledgment across the network following in reverse the path taken by the data packet being acknowledged, and updating a state of the or each network link in the path taken by the data packet being acknowledged in response to receipt of such a delivery acknowledgement, wherein each network link in the multi-path network comprises a plurality of individually selectable link channels for transmitting data packets across the network and wherein a link channel may be individually exclusively assigned to data packets having common packet ordering requirements until at least one acknowledgement of a data packet is transmitted by an exclusively assigned link channel, wherein each network element maintains an acknowledgment count value in association with each link channel with which it is connected, the acknowledgement count value being incrementally adjusted by amounts representative of the data packets delivered to network egress ports transmitted by the link channel, and wherein each network element compares the packet count value and the acknowledgement count value for a link channel and wherein the link channel remains exclusively assigned to data packets having packet ordering requirements matching the most recent data packet transmitted by that link channel when there is a difference between the packet count value and the acknowledgement count value for said link channel.