Software Flow Table Handling for Hardware Hash Collision Packets

Solution Overview

Problem

Existing network devices face reduced packet forwarding efficiency due to hash collisions exceeding the limit of hardware-accelerated forwarding circuits, leading to increased CPU resource occupation and processing overhead.

Innovation Solution

Implement a network device with a software flow table and a network processing unit (NPU) to handle packets that experience hash collisions in the hardware flow table, offloading CPU workload and enhancing forwarding efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If hardware-accelerated forwarding circuit is used to improve packet forwarding efficiency, then forwarding speed is improved, but hash collisions cause packets to be transmitted to CPU which reduces overall efficiency

Engineering Contradiction:

Improvepacket forwarding speedVSAvoidoverall packet forwarding efficiency

Core Design Contradiction:

SpeedVSProductivity

Solution Approach 1:

The patent segments the forwarding system into two parts: a hardware flow table for common packets and a software flow table for hash collision packets. The hardware flow table handles the majority of packets at high speed, while the software flow table specifically handles hash collision cases, preventing them from occupying CPU resources for general processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a software flow table as an intermediary between the hardware flow table and CPU processing. When hash collisions occur in the hardware flow table, packets are redirected to the software flow table for handling, rather than directly to the CPU, thus reducing CPU intervention and maintaining high forwarding efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If CPU executes software to handle hash collision packets, then packet forwarding is possible, but processor resource occupation increases

Engineering Contradiction:

Improvepacket forwarding capabilityVSAvoidCPU processor resource occupation

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent segments the forwarding system into two parts: a hardware flow table for common packets and a software flow table for hash collision packets. The hardware flow table handles the majority of packets at high speed, while the software flow table specifically handles hash collision cases, preventing them from occupying CPU resources for general processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a software flow table as an intermediary between the hardware flow table and CPU processing. When hash collisions occur in the hardware flow table, packets are redirected to the software flow table for handling, rather than directly to the CPU, thus reducing CPU intervention and maintaining high forwarding efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If hardware flow table size is increased to reduce hash collisions, then forwarding efficiency is improved, but device complexity and cost increase

Engineering Contradiction:

Improvepacket forwarding efficiencyVSAvoidhardware flow table complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Instead of expanding the hardware flow table in one dimension (size), the patent adds another dimension by introducing a software flow table. This software layer handles hash collision cases without requiring expansion of the hardware flow table, thus avoiding increased device complexity and cost while maintaining high forwarding efficiency.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20260005962A1Network device using software flow table and network processing unit for packet forwarding and related packet forwarding method

Publication Date: 2026.01.01 AIROHA TECH (SUZHOU) LTD

AI summary

A network device includes a storage device, a hardware-accelerated forwarding circuit, and a network processing unit (NPU). The storage device stores a software flow table, where the software flow table includes a plurality of table entries. The hardware-accelerated forwarding circuit receives a first packet from a network, obtains a first hash value of the first packet, and determines that the first hash value encounters a hash collision in a hardware flow table. The NPU receives the first packet from the hardware-accelerated forwarding circuit, and deals with forwarding of the first packet according to forwarding information recorded in a table entry when the first packet hits the table entry of the software flow table.