International Business Machines Corporation

James John Martin

James P Gray

Brad Alan Makrucki

Raymond F Bird

Ralph Benjamin Case

Methods, apparatus and computer program products are provided for distributing communication packets over multiple concurrent parallel links between a first node and a second node in a communication network based upon link quality information for the links. By utilizing link quality information from the links, the rate at which packets are provided to the links may be made proportional to the quality of the link, and thus, the link's ability to transmit the packet. The rate at which packets are provided to links may be reduced when error rates on a link exceed a specified threshold and eliminated when error rates exceed a higher threshold. Alternatively, timing delays from errors on a link may be used to determine a delay factor for a link and packets scheduled to the links based on the link with the lowest delay. The present invention is particularly useful in High Performance Routing Multilink Transmission Groups.

Optimal link scheduling for multiple links

A technique for adapting receiver thresholds to improve rate-based flow control in a data communications network. With this invention, the flow control process becomes self-calibrating such that threshold values are dynamically adjusted to adapt to current network conditions, without requiring user intervention. Several different indicators of network conditions are monitored, and appropriate adjustments are made to the threshold(s) upon detecting these specific indicators. One monitor enables the threshold to increase when the network is uncongested, enabling the sender to increase its transmission rate. Conversely, the threshold is lowered if the network is congested, so that the transmission rate will be decreased. Another monitor balances bandwidth allocation among connections sharing a bottleneck resource, by lowering the threshold (and therefore decreasing the send rate) when a connection uses a high share of the resource. A third monitor detects the presence of traffic from protocols not using adaptive receiver thresholds, and adjusts the threshold (including an upper and lower threshold bound) in order to compete fairly for resources with these other protocols. The monitors may be implemented individually or in combination.

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Cary, NC, United States of America

James John Martin