Path Congestion Notification for Dynamic Multipath Routing
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Solution Overview
Problem
Ingress nodes in multipath networks are unable to detect and mitigate congestion along paths due to lack of awareness from transit nodes, leading to packet drops and inefficiencies in resource utilization.
Innovation Solution
Implementing path congestion notification (path-CN) messages that allow transit nodes to notify ingress nodes of congestion, enabling them to divert packets to alternate paths, using unique node and path identifiers encoded in packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transit nodes forward packets without notifying ingress nodes of congestion, then network operation is simple and fast, but packet drops increase and resource utilization deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where transit nodes send path congestion notification (path-CN) messages back to ingress nodes when congestion is detected. This feedback loop enables ingress nodes to adjust their packet forwarding decisions dynamically, diverting traffic from congested paths to alternative paths, thereby maintaining high throughput while reducing packet drops through informed routing decisions.
2Reliability
If path congestion notification messages are implemented, then packet delivery reliability improves, but network message overhead and complexity increase
Solution Approach 1:
The patent extracts the congestion notification function into a separate, dedicated message type (path-CN message) rather than embedding congestion information in existing packet formats. This extraction allows for standardized, lightweight notification messages that can be processed efficiently by network nodes without requiring complex modifications to existing routing protocols or packet structures.
3Productivity
If ingress nodes lack awareness of path congestion, then forwarding decisions are simple and fast, but resource utilization deteriorates due to inability to divert packets
Solution Approach 1:
The patent implements a self-service mechanism where transit nodes autonomously monitor their own congestion states and generate path-CN messages when needed. Each transit node independently tracks queue depths and congestion conditions on its outgoing interfaces, eliminating the need for centralized congestion monitoring or complex coordination between nodes, thereby improving resource utilization with minimal added complexity.
Data Source
AI summary
An ingress node includes a transceiver that transmits a packet along a first path from the ingress node to an egress node. The packet includes a globally unique node identifier (node ID) for the ingress node and a path identifier (path ID) of the first path. The transceiver also receives a path congestion notification (path-CN) message in response to congestion along the first path. The path-CN message is addressed to the ingress node based on the node ID and includes the path ID. The ingress node also includes a processor that selects a second path in response to receiving the path-CN message. The transceiver transmits subsequent packets in the flow along the second path. Transit nodes include a transceiver that receives packets including the node ID and the path ID. A processor in the transit node generates the path-CN message based on the node ID.