Ethernet MAC Table Traffic Prioritization During CPU Congestion
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Solution Overview
Problem
Network devices often become burdened with excessive or complex traffic, leading to indiscriminate dropping of packets, particularly during denial of service attacks, due to the lack of hardware-based Quality of Service (QOS) functionality in Ethernet interfaces to prioritize management traffic.
Innovation Solution
The method involves maintaining a MAC table that distinguishes between general and prioritized traffic by disabling MAC addresses associated with general traffic when the CPU is congested, allowing only prioritized traffic to be processed, and re-enabling general traffic once the burden subsides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CPU processes all incoming traffic, then complete traffic handling is achieved, but the CPU becomes burdened and cannot prioritize management traffic during congestion
Solution Approach 1:
The patent segments traffic into different priority categories (management traffic vs. general traffic) and processes them through different paths. The MAC table is segmented to store priority MAC addresses separately, allowing the system to quickly identify and prioritize management traffic without processing all traffic uniformly through the CPU.
Solution Approach 2:
The patent performs preliminary classification of traffic at the Ethernet interface level using the MAC table before traffic reaches the CPU. By pre-identifying priority traffic through destination MAC address matching in the MAC table, the system prepares traffic prioritization in advance, so that during CPU congestion, management traffic is already flagged for priority processing.
2Reliability
If hardware-based QOS functionality is used to prioritize traffic, then management traffic is prioritized, but network devices without such hardware cannot implement prioritization
Solution Approach 1:
The patent creates a universal traffic prioritization mechanism that works on any Ethernet interface with a MAC table, regardless of whether the device has specialized hardware-based QOS functionality. The solution uses the existing MAC table structure for prioritization, making it adaptable to various network devices including those without dedicated QOS hardware.
Solution Approach 2:
The MAC table serves dual purposes: its traditional function of MAC address filtering and the additional function of traffic prioritization. By utilizing the existing MAC table infrastructure for priority identification, the system makes the network device self-sufficient for prioritization without requiring external or specialized hardware components.
3Measurement precision
If the CPU processes complicated traffic requiring extra processing, then thorough packet inspection is achieved, but the CPU becomes burdened and drops packets indiscriminately
Solution Approach 1:
The patent applies different processing qualities to different packets based on their priority. Priority packets (management traffic) identified through MAC table matching receive thorough CPU processing, while non-priority packets receive minimal or no CPU processing. This local differentiation of processing quality ensures that critical packets are inspected accurately while reducing overall CPU burden.
Solution Approach 2:
The patent changes the processing parameter (level of inspection) based on packet priority. By modifying the processing depth and intensity according to whether a packet is identified as management traffic through MAC address matching, the system achieves accurate inspection of critical packets while maintaining high packet delivery rates overall by reducing inspection of non-critical packets.
Data Source
AI summary
A system and method is provided for prioritizing packets at an Ethernet interface of a network device based on the destination MAC address in the packets. The Ethernet interface has a MAC table that lists the MAC addresses that can be accepted by the Ethernet interface. The MAC table can include one or more MAC addresses associated with low priority packets and one or more MAC addresses associated with high priority packets. When conditions at the network device exceed a threshold, the MAC table can be updated to disable or delete the MAC addresses associated with the low priority packets. By disabling the MAC addresses for low priority packets, only the MAC addresses associated with high priority packets remain in the MAC table, thereby enabling only high priority packets to be recognized and passed by the Ethernet interface to the CPU.