Switch Loop Failure Handling via MAC Flapping Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing network technologies face challenges in efficiently handling loop failures in Ethernet networks, leading to service interruptions due to simultaneous loop protection actions by multiple switches, which can cause broadcast storms and disrupt network services.
Innovation Solution
A method where a switch identifies flapping ports by tracking MAC address movements and determines a primary and secondary port to selectively enable flooding suppression, preventing the forwarding of flooding packets while allowing other types of packets to pass through, thereby avoiding service interruptions and reducing the impact of loop failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple switches simultaneously perform loop protection actions by blocking faulty ports, then broadcast storms are suppressed, but normal network services are interrupted
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different ports based on their role in the loop. Instead of uniformly blocking all detected faulty ports, the system identifies the primary faulty port (where the loop packet first enters the switch) and blocks only that specific port. Secondary ports that also detect loops are not blocked, allowing normal traffic to flow through them. This localized differentiation resolves the contradiction by suppressing broadcast storms at the source while preserving network service continuity through alternative paths.
2Stability of the object's composition
If all flapping ports are blocked to prevent broadcast storms, then network stability is improved, but service interruption occurs
Solution Approach 1:
The patent segments the set of flapping ports into two categories: primary faulty ports and secondary ports. The primary faulty port is identified as the port where the loop packet first enters the switch (determined by comparing the incoming port with the learned MAC address table). Only this segmented primary port is blocked to prevent broadcast storms. The secondary ports are excluded from blocking, maintaining service availability. This segmentation resolves the contradiction by applying stability measures only where necessary while preserving service continuity elsewhere.
3Reliability
If ring protection protocols like STP or ERPS are deployed, then logical loop-free network is achieved, but the protocols cannot resolve loops caused by incorrect wiring or configuration
Solution Approach 1:
The patent implements a self-service loop detection and protection mechanism that operates independently of external ring protection protocols. Each switch autonomously generates loop detection packets, monitors for their return, and identifies faulty ports based on local MAC address table comparisons. This self-service approach resolves loops caused by incorrect wiring or configuration without requiring protocol coordination, thereby improving adaptability while maintaining the logical loop-free property provided by STP or ERPS.
Solution Approach 2:
The patent introduces loop detection packets as an intermediary mechanism to bridge the gap between physical loop conditions and logical loop-free operation. These packets circulate through the network to detect physical loops, and their return to the source switch provides evidence of loop conditions. This intermediary enables the system to identify and block faulty ports regardless of whether ring protection protocols are properly configured, enhancing the system's ability to resolve various loop failure scenarios.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention discloses a loop failure handling method and a switch. A switch receives a first packet, where the first packet includes a source media access control MAC address. The switch obtains a first flapping count corresponding to the source MAC address. The switch determines, based on the first flapping count, whether a loop failure occurs in a network in which the switch is located. When the loop failure occurs in the network in which the switch is located, the switch obtains a flapping port set corresponding to the source MAC address. The switch determines a primary port in the plurality of ports, where the primary port is a port that must be suppressed. The switch enables a flooding suppression function on the primary port, where the flooding suppression function is used to suppress forwarding of a received flooding packet by the primary port. When a loop failure occurs in the network, the switch in the present invention is capable of avoiding a service interruption while avoiding a broadcast storm in the network.