Spine-Leaf Load Balancing via Real-Time Congestion Feedback

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Solution Overview

Problem

Current load balancing algorithms in spine-leaf network architectures are limited by slow and non-real-time feedback loops, which hinder the ability to dynamically adapt to changing traffic loads, leading to suboptimal selection of spine switches for data flow routing.

Innovation Solution

Implementing a feedback loop between the leaf-spine fabric and the controller to provide real-time load information, allowing the controller to adjust the load balancing algorithm and select the most optimal spine switches for traffic routing, using techniques such as replicating packets across multiple spine switches and gathering metrics on congestion levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If real-time feedback loop is implemented to dynamically adjust load balancing, then network responsiveness and adaptability improve, but system complexity increases

Engineering Contradiction:
Improveload balancing adaptabilityVSAvoidfeedback loop complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where egress leaf switches send congestion metrics back to ingress leaf switches, enabling dynamic adjustment of load balancing decisions. This feedback loop allows the network to adapt to changing traffic conditions in real-time, resolving the contradiction by making the system adaptable while managing complexity through structured metric collection and algorithm adjustment.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The load balancing algorithm transitions from static to dynamic by continuously adjusting weight values based on real-time congestion metrics. The system dynamically modifies routing decisions based on current network conditions, achieving adaptability while maintaining manageable complexity through parameter-based adjustment rather than structural changes.

Inventive Principle:
Principle #15Dynamics

2Productivity

If multiple copies of packets are transmitted across multiple spine switches, then load balancing effectiveness improves, but network traffic overhead increases

Engineering Contradiction:
Improveload balancing effectivenessVSAvoidnetwork traffic volume
Core Design Contradiction:
ProductivityVSQuantity of substance

Solution Approach 1:

The patent changes parameters (congestion metrics, weight values) to optimize packet routing decisions. By adjusting the weight parameter in the load balancing algorithm based on real-time congestion data, the system achieves effective load balancing without unnecessarily duplicating packets, thus improving productivity while controlling traffic overhead.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system transmits packet copies to multiple spine switches only when beneficial for load balancing, not always. The ingress leaf switch uses the load balancing algorithm to determine the optimal number and selection of spine switches for each packet, applying partial action (selective replication) rather than excessive action (universal replication), thereby balancing effectiveness with traffic overhead.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS11303586B2Switching and load balancing techniques in a communication network
Publication Date: 2022.04.12 CISCO TECHNOLOGY INC
  • US11303586B2 patent drawing
  • US11303586B2 patent drawing
  • US11303586B2 patent drawing

AI summary

A source access network device multicasts copies of a packet to multiple core switches, for switching to a same target access network device. The core switches are selected for the multicast based on a load balancing algorithm managed by a central controller. The target access network device receives at least one of the copies of the packet and generates at least metric indicative of a level of traffic congestion at the core switches and feeds back information regarding the recorded at least one metric to the controller. The controller adjusts the load balancing algorithm based on the fed back information for selection of core switches for a subsequent data flow.