Destination-Based Congestion Control in InfiniBand Networks
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Solution Overview
Problem
Existing congestion control methods in communication networks often fail to effectively mitigate network congestion without unnecessarily reducing the transmission rate of packet flows that do not contribute to congestion, particularly in Infiniband networks where a single Queue Pair is used for sending packets to multiple destinations.
Innovation Solution
The method involves identifying the network address of a congested destination interface through notifications and regulating the transmission rate of subsequent packets addressed to that address, irrespective of the transport service instance, by using rate limiting circuits to enforce a minimum delay between packets, thus targeting only congested paths while minimizing impact on non-congested ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If congestion control mechanisms regulate transmission rate based on transport service instance (Queue Pair), then congestion mitigation is achieved, but transmission rate of non-congested packet flows is unnecessarily reduced
Solution Approach 1:
The patent applies local quality by transitioning from transport service instance-level congestion control to destination address-level control. Instead of regulating all packets from a Queue Pair regardless of destination, the system selectively regulates only packets destined to congested addresses. This is achieved by identifying the destination address from congestion notifications and applying rate limiting specifically to packets with matching destination addresses, thereby maintaining high transmission rates for non-congested flows while effectively mitigating congestion at specific destinations.
2Device complexity
If transmission rate is regulated per transport service instance, then congestion control is simpler to implement, but granularity of congestion control is too coarse
Solution Approach 1:
The patent applies segmentation by dividing the congestion control scope from the transport service instance level down to the destination address level. Instead of treating all packets from a Queue Pair uniformly, the system segments the control granularity to identify and regulate only those packets destined to specific congested addresses. This is implemented by extracting destination addresses from congestion notifications and maintaining separate rate limiting states for each destination address, achieving fine-grained control without requiring complete redesign of the congestion control architecture.
3Reliability
If congestion control is applied to all packets from a Queue Pair, then congestion mitigation is comprehensive, but performance trade-off is reduced due to over-regulation
Solution Approach 1:
The patent applies feedback by utilizing destination address information from congestion notifications to dynamically adjust rate limiting behavior. Instead of applying uniform rate limiting to all packets from a Queue Pair, the system uses the destination address feedback to selectively apply rate limiting only to packets destined to congested addresses. This feedback mechanism enables the system to maintain comprehensive congestion mitigation at targeted destinations while preserving high transmission performance for flows to non-congested destinations, thereby optimizing the overall performance trade-off.
Data Source
AI summary
A method for communication includes sending communication packets over a network from a first network interface. A notification, which originates from a second network interface and indicates a network congestion encountered by one or more of the packets, is received in the first network interface. A network address of the second network interface is identified based on the notification. A transmission rate of subsequent packets addressed to the network address is regulated responsively to the notification, irrespective of a transport service instance on which the subsequent packets are sent from the first network interface.