STP Engine Virtual Port Designation for N-Node Link Aggregation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional spanning tree protocols block Inter-Chassis Links (ICLs) between Virtual Link Trunking (VLT) nodes, even when there are no data loops, leading to unnecessary bandwidth waste and inefficiencies in n-node VLT systems.
Innovation Solution
An Information Handling System (IHS) with a spanning tree protocol engine that designates virtual ports and non-LAG ports dynamically, allowing the spanning tree protocol to operate without blocking ICLs between VLT nodes, by treating virtual ports as point-to-point links and using a link aggregation fabric manager to prevent data loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional spanning tree protocol is used to prevent data loops in VLT systems, then data loop prevention is achieved, but Inter-Chassis Links (ICLs) between VLT nodes are blocked even when no data loops exist, causing bandwidth waste
Solution Approach 1:
The system segments the network into virtual ports and physical ports, applying different spanning tree protocol rules to each. Virtual ports (representing ICLs between VLT nodes) are excluded from spanning tree calculations, while physical ports connected to external devices are subject to normal spanning tree protocol operation. This segmentation allows ICLs to remain active without causing loops, while still preventing loops through external devices.
Solution Approach 2:
The patent introduces a fabric manager as an intermediary component that operates between the spanning tree protocol and the ICLs. The fabric manager prevents data loops by monitoring and controlling traffic across the ICLs, allowing these links to remain active without requiring the spanning tree protocol to block them. This intermediary layer provides loop prevention specifically tailored to the VLT architecture without the limitations of conventional spanning tree protocol.
2Stability of the object's composition
If the spanning tree protocol blocks ICLs to prevent loops, then loop-free operation is ensured, but network efficiency and bandwidth utilization deteriorate
Solution Approach 1:
The system applies different quality rules to different parts of the network. ICLs between VLT nodes are treated with special local quality rules that exclude them from spanning tree protocol blocking decisions, allowing them to operate at full capacity. Other physical ports are subject to standard spanning tree protocol rules. This localized differentiation maintains loop-free operation while maximizing network efficiency for critical ICL paths.
Solution Approach 2:
The system dynamically adjusts port roles and spanning tree protocol behavior based on the specific port type and network conditions. Virtual ports representing ICLs are dynamically excluded from spanning tree calculations, while physical ports dynamically respond to spanning tree protocol decisions. This dynamic adaptation allows the network to maintain stability while optimizing bandwidth utilization for time-sensitive applications over ICLs.
Data Source
AI summary
A STP n-node VLT system includes a first VLT device with a first virtual port, and a second VLT device with a LAG port, a non-LAG port, and a second virtual port coupled to the first virtual port. A STP engine designates the first VLT device as a root bridge and, in response, designates the first virtual port a designated port and the second virtual port a root port. The STP engine then designates a networking device coupled to the LAG port as the root bridge based on it having a higher priority than the first VLT device. Then STP engine then determines that a non-LAG link between the networking device and the second VLT device has caused the redesignation of the second virtual port as an alternate port and the non-LAG port as a root port, and swaps the designations of the second virtual port and the non-LAG port.