Hierarchical Interconnection Network with Minus-First Routing
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Solution Overview
Problem
Existing interconnection networks face challenges in achieving low latency and high scalability while maintaining low cost, as they often require high-radix routers with complex virtual channel designs that increase latency and design complexity.
Innovation Solution
A hierarchical interconnection network with a four-layer architecture and a partially-adaptive routing algorithm that reduces global connections and eliminates the need for virtual channels, using minus-first routing to ensure deadlock-free communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high-radix routers with virtual channels are used to achieve deadlock-free adaptive routing, then routing adaptability is improved, but device complexity increases due to multiple virtual channels
Solution Approach 1:
The patent extracts and eliminates the virtual channel mechanism from the routing system. By using a single real channel instead of multiple virtual channels, the design achieves deadlock-free adaptive routing without the complexity of virtual channel management, state tracking, and switching fabric requirements
Solution Approach 2:
The patent changes the fundamental parameter of channel quantity from multiple virtual channels to a single real channel. This parameter change, combined with the minus-first routing algorithm, transforms the system from requiring complex virtual channel infrastructure to using simple real channel infrastructure while maintaining or improving routing adaptability
2Productivity
If high-radix routers are deployed to reduce network diameter and improve scalability, then network performance is improved, but cost increases due to higher radix requirements
Solution Approach 1:
The patent segments the network into hierarchical domains (racks, clusters, data centers) and applies appropriate routing strategies to each segment. This segmentation allows the use of moderate-radix routers within segments while achieving scalable performance across the entire network through hierarchical interconnection
Solution Approach 2:
The patent introduces hierarchical dimensionality to the network architecture, organizing routers and connections across multiple levels (intra-rack, inter-rack, inter-cluster). This dimensional organization reduces the radix requirement at each individual router while maintaining overall network performance through efficient hierarchical routing
3Quantity of substance
If more global connections are added to increase network bandwidth, then communication capacity is improved, but latency increases due to longer communication paths
Solution Approach 1:
The patent applies local quality by optimizing communication within local domains (racks and clusters) before extending to global communication. Local traffic is handled with low-latency direct connections, while global traffic uses hierarchical routing that minimizes hops, ensuring that bandwidth expansion does not uniformly increase latency across all communication patterns
4Adaptability or versatility
If virtual channels are implemented to enable adaptive routing, then routing flexibility is improved, but design complexity increases
Solution Approach 1:
The patent extracts the essential function of adaptive routing (deadlock-free flexible path selection) from the complex virtual channel mechanism. By using the minus-first routing algorithm on simple real channels, it achieves routing flexibility without virtual channel overhead, eliminating the need for virtual channel state management and complex switching logic
Solution Approach 2:
The routing algorithm itself provides the adaptability and deadlock prevention functions that would otherwise require virtual channel infrastructure. The minus-first algorithm inherently prevents deadlocks through its deterministic hop selection, making external virtual channel mechanisms unnecessary for achieving routing flexibility
Data Source
AI summary
This invention proposes a new communication locality oriented high-radix (CLHR) network. In this hierarchical architecture, the lowest level includes routers or servers, called level-0; the upper level is composed by groups of routers or servers, called level-1; for the highest level, a number of level-(l−1) groups establish level-1 group. A new deadlock-free adaptive routing algorithm is proposed for the CLHR network. On the one hand, the proposed minus-first routing (MFR) algorithm or plus-first routing algorithm, that implements deadlock-free partially-adaptive routing without any virtual channel, can guarantee the number of communication hops between two nodes is no more than five. On the other hand, this invention presents the fully adaptive routing algorithm that uses MFR algorithm as the baseline routing using a new flow control scheme. The CLHR network and the new routing algorithm effectively improve the performance, save energy, improve the ability for separation, and resist disturbance.