Flexible Clos Topology Switch with Tiered Traffic Routing
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Solution Overview
Problem
Existing network technologies face challenges in scaling switch bandwidth and radix efficiently, particularly in Clos topology switches, which often result in high costs, large size, and resource-intensive solutions due to the need for numerous switches and extensive connections.
Innovation Solution
A compact Clos topology switch design is implemented, where the number of external port connections exceeds the internal connections between leaf and spine switches, allowing for a higher ratio of leaf switches to spine switches, thereby reducing costs, size, and resource overhead, and optimizing traffic forwarding at the leaf level to minimize spine switch usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional Clos topology switches are used to scale switch bandwidth and radix, then network capacity is improved, but cost and device size increase due to numerous switches and extensive connections
Solution Approach 1:
The network is segmented into multiple tiers (lower tier, middle tier, upper tier) with specialized functions. The middle tier uses a compact Clos topology with fewer switches, while lower and upper tiers handle specific traffic types. This segmentation allows each tier to be optimized independently, reducing overall complexity while maintaining high bandwidth and radix capabilities.
Solution Approach 2:
The patent introduces a hierarchical dimension to the traditional Clos topology by adding tier levels (lower, middle, upper). Instead of using a single large Clos fabric, the solution distributes switching functions across multiple tiers, with the middle tier providing a compact Clos topology that reduces the number of switches needed while maintaining scalability through vertical tiering.
2Productivity
If more spine switches are deployed to increase network capacity, then bandwidth is improved, but resource overhead and cost increase
Solution Approach 1:
Different tiers are assigned different qualities and functions: lower tier switches handle east-west traffic with high port counts, middle tier provides compact Clos topology for north-south routing, and upper tier handles additional north-south traffic. This local quality differentiation allows bandwidth to be achieved without uniformly increasing spine switch quantity throughout the entire network.
Solution Approach 2:
The patent uses multiple leaf switches in the middle tier that each provide connectivity to fewer spine switches, effectively copying the leaf switch functionality across multiple instances. This allows the network to achieve high bandwidth through parallel leaf switch paths rather than requiring a proportional increase in spine switches.
3Device complexity
If a compact Clos topology with fewer internal connections is used, then device size and cost are reduced, but traffic forwarding efficiency may be impacted
Solution Approach 1:
The patent implements dynamic traffic routing where east-west traffic is forwarded at the leaf level within the middle tier, while north-south traffic is routed through spine switches. This dynamic routing strategy adapts to traffic patterns, ensuring efficient forwarding despite reduced internal connections by utilizing the hierarchical tier structure and selective routing paths.
Data Source
AI summary
In one embodiment, a computer network system, includes at least one lower tier of lower switches, at least one upper tier of upper switches, and a middle tier of middle switches connected down-tier to ones of the lower switches and up-tier to ones of the upper switches, one of the middle switches including a clos topology arrangement of leaf and spine switches, the leaf switches being connected via K internal network connections to the spine switches, each leaf switch being connected to each spine switch, the leaf switches being connected via N down-tier network connections to ones of the lower switches and via M up-tier network connections to ones of the upper switches, there being more of the N down-tier network connections than there are of the M up-tier network connections, and there being less of the K internal network connections than there are of the N and M connections.