Hierarchical Switching Device with Exclusive Queue Partitions
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Solution Overview
Problem
Network switching devices often face port-to-port dependencies, which can lead to deadlocks and inefficiencies, particularly in hierarchical designs where careful design practices are needed to avoid such dependencies and ensure deadlock freedom.
Innovation Solution
A hierarchical switching device architecture is implemented using a fully interconnected all-to-all network of sub-switches with exclusive queue partitions for each external output port, allowing for independent packet flow and minimizing dependencies, thereby avoiding deadlocks and reducing head-of-line blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a hierarchical switching device is implemented to reduce size, then the device complexity is reduced, but port-to-port dependencies may be created causing deadlocks
Solution Approach 1:
The patent divides the switching device into multiple sub-switches organized in a hierarchical structure with input ports, intermediate ports, and output ports. This segmentation reduces the overall device complexity while maintaining deadlock freedom through careful design of inter-sub-switch connections and routing algorithms that avoid port-to-port dependencies.
Solution Approach 2:
The patent introduces intermediate ports as mediators between input ports and output ports in the hierarchical structure. These intermediate ports act as buffer zones that prevent direct port-to-port dependencies, allowing packets to be routed through multiple stages without creating deadlock conditions while maintaining reduced device complexity.
2Reliability
If routing algorithms avoid port-to-port dependencies to ensure deadlock freedom, then reliability is improved, but routing complexity increases
Solution Approach 1:
The routing algorithm is segmented into multiple stages corresponding to the hierarchical structure of sub-switches. Each stage handles specific routing decisions (input to intermediate, intermediate to output) independently, which simplifies the overall routing complexity while ensuring deadlock freedom through the structured avoidance of port-to-port dependencies.
Solution Approach 2:
The patent implements preliminary routing decisions at each hierarchical stage, where routing paths are determined and committed at intermediate ports before final output selection. This preliminary action simplifies subsequent routing decisions and ensures deadlock freedom by establishing clear, dependency-free paths in advance.
3Device complexity
If hierarchical structure is used to reduce size, then device complexity is reduced, but head-of-line blocking increases
Solution Approach 1:
The patent segments the packet flow into multiple independent streams through the hierarchical sub-switches, where each sub-switch handles specific portions of traffic. This segmentation reduces head-of-line blocking by allowing parallel processing of packets at different hierarchical levels, maintaining productivity while reducing device complexity.
Solution Approach 2:
The patent introduces an additional hierarchical dimension to the switching architecture, organizing sub-switches in multiple levels with intermediate ports. This dimensional expansion provides alternative routing paths and reduces head-of-line blocking by distributing packet flow across multiple hierarchical layers, thereby maintaining productivity while achieving compact device size.
Data Source
AI summary
Examples relate to hierarchical switching devices comprising a plurality of sub-switches forming a fully interconnected all-to-all network. The sub-switches comprise internal input ports and internal output ports to exchange packets with other sub-switches within the fully interconnected all-to-all network. The internal input ports of the sub-switches have exclusive access to a queue partition for each external output port of the respective sub-switch. A switch controller receives a packet at a first sub-switch of the plurality of sub-switches that is to be routed to a particular external output port of a second sub-switch of the plurality of sub-switches. The switch controller routes the packet directly from the first sub-switch to the second sub-switch using an internal output port of the first sub-switch and a queue partition of the second sub-switch that is for the particular external output port of the second sub-switch.