Relay System Link Aggregation Loop Prevention
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Solution Overview
Problem
Conventional methods for handling network loops in switch stacking with link aggregation, such as STP and TTL, are ineffective in utilizing the link aggregation group efficiently and can lead to frame storms due to redundant frame transmission.
Innovation Solution
A relay system with a learning control unit and a filtering unit that manages correspondence information between MAC addresses and ports, preventing redundant frame transmission by selectively routing frames through different lines within a link aggregation group, thereby avoiding network loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If link aggregation is employed to connect multiple switches to a node, then communication bandwidth is improved and redundancy is ensured, but network loops are formed causing frame storms
Solution Approach 1:
The patent segments the link aggregation group into multiple individual link relationships, each managed separately with unique MAC address assignments. This segmentation allows the system to maintain multiple physical connections while avoiding loops by ensuring each link is independently identified and controlled, thus preserving bandwidth benefits without the frame storm problem.
Solution Approach 2:
The patent introduces MAC address assignment as an intermediary mechanism to manage link aggregation. By assigning unique MAC addresses to each link relationship and using these addresses in frame transmission, the system can identify and control individual links within the aggregation group, preventing loop formation while maintaining the redundancy and bandwidth benefits of multiple connections.
2Reliability
If spanning tree protocol is used to block redundant paths, then network loops are prevented, but link aggregation efficiency is reduced due to blocked paths
Solution Approach 1:
Instead of blocking entire paths as STP does, the patent segments the link aggregation group into independently managed link relationships. Each link can be actively utilized with unique MAC address identification, allowing all links in the aggregation group to contribute to bandwidth while loop prevention is achieved through the unique addressing scheme rather than path blocking.
Solution Approach 2:
The patent inverts the conventional approach by not blocking redundant paths but instead uniquely identifying each path with distinct MAC addresses. This inversion allows all paths to remain active and contribute to bandwidth while the unique addressing prevents frame storms, achieving both loop prevention and full link utilization simultaneously.
3Reliability
If TTL values are used to eliminate loops, then frame circulation is stopped, but link aggregation efficiency is not improved and frame storms may still occur
Solution Approach 1:
The patent applies preliminary action by assigning unique MAC addresses to each link relationship before frame transmission occurs. This pre-configuration enables the system to identify and control frame paths in advance, preventing frame storms at the source rather than relying on TTL-based reactive elimination. The unique MAC addressing allows all link aggregation paths to be actively utilized from the beginning.
Solution Approach 2:
The patent replaces the TTL-based mechanical counting system with a MAC address-based identification system. Instead of relying on decrementing TTL values to eventually stop frame circulation, the system uses unique MAC addresses to proactively identify and control each link relationship, allowing full link aggregation efficiency while preventing frame storms through deterministic address matching rather than probabilistic TTL expiration.
Data Source
AI summary
A relay system includes a first relay apparatus connected to a node through a first line and a second relay apparatus connected to the node through a second line. The first line and the second line belong to the same link aggregation group. The first relay apparatus includes a first control unit. The first control unit notifies, before relaying a received frame, the second relay apparatus of a source address included in the received frame in the absence of first relation information related to the source address in the first storage unit upon receiving the received frame via a port connected to the first line. The second relay apparatus includes a second control unit. The second control unit stores, in the second storage unit, second relation information regarding a relationship between the source address notified by the first relay apparatus and an output port connected to the second line.