STP Alternate Tree Path Activation for Network Flow Control
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Solution Overview
Problem
The Spanning Tree Protocol (STP) in communication networks can lead to slowdowns in entire network sections when a receiver or intermediate node is slower than the transmitter, as it requires pause frames to modulate traffic, affecting the flow control and causing bottlenecks.
Innovation Solution
A network device with an ingress module, pause frame detector, and alternative network path activator that detects pause frames and activates a different network path based on queue fullness levels and STP criteria to reroute traffic, ensuring continuous flow without bottlenecks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pause frames are used to modulate traffic flow control, then the receiver can control its input rate to match its processing speed, but the entire network section slows down due to the bottleneck effect
Solution Approach 1:
The network traffic is segmented into different paths (primary STP path and alternate tree path). When the primary path experiences flow control pauses, traffic is automatically redirected to the alternate path, allowing segmentation of the traffic flow to avoid bottleneck effects while maintaining flow control reliability on the congested link.
Solution Approach 2:
The solution adds a dimensional aspect to path selection by introducing an alternate tree path as a secondary dimension for traffic flow. When the primary STP path becomes congested (indicated by pause frames), the system transitions to using the alternate path, effectively adding a temporal and spatial dimension to path selection that prevents network-wide slowdowns.
2Reliability
If the receiver sends pause frames to control traffic flow, then buffer overflow is prevented, but network latency increases due to traffic modulation
Solution Approach 1:
The system performs preliminary actions by detecting pause frames and queue fullness levels before completely congesting the buffer. When pause frames are detected or queue fullness exceeds a threshold, the system proactively activates the alternate tree path, preventing buffer overflow before it occurs and avoiding the latency associated with reactive buffer management.
Solution Approach 2:
The alternate tree path acts as an intermediary channel that absorbs traffic when the primary path experiences flow control pauses. This intermediary path prevents direct confrontation between transmitter output rate and receiver processing rate, allowing smooth traffic redirection without the latency penalties of pause frame-based flow control.
3Device complexity
If a single network path is used for traffic transmission, then path management is simple, but network robustness decreases when the path becomes congested
Solution Approach 1:
The system implements dynamic path selection where the active path changes based on real-time network conditions. The network device monitors pause frames and queue fullness levels, dynamically switching between the primary STP path and the alternate tree path. This dynamic approach maintains simplicity during normal operation while providing robustness when congestion occurs.
Solution Approach 2:
The system changes operational parameters (active path selection) based on network conditions. When pause frames are detected or queue fullness exceeds thresholds, the parameter representing the active path changes from the primary STP path to the alternate tree path. This parameter-based control maintains management simplicity while enhancing network robustness through adaptive path selection.
Data Source
AI summary
A network device activates an alternative path flow control for spanning tree protocol. The network device includes a receiver that receives first network traffic from a first transmitter of the first network traffic, the first network traffic being destined for a first receiver along a first network path, and receives second network traffic from the first receiver, the second network traffic being destined for at least the first transmitter along a second network path. The network device also has a pause frame detector configured to detect in the second network traffic a pause frame for controlling a flow of the first network traffic. The network device, furthermore, has an alternative network path activator configured to activate, a third network path that is different from the first network path, for transmitting the first network traffic to the first receiver.