Wireless Link Aggregation via MAC Hashing and Dynamic Rewriting
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Solution Overview
Problem
Existing methods for aggregating multiple wireless links for Ethernet bridging face issues such as forwarding loops, ineffective load balancing due to RF fluctuations, and false link failure detection, which hinder the achievement of high throughput and reliable performance.
Innovation Solution
A system utilizing a hash function on destination MAC addresses to prevent forwarding loops and ensure unique frame transmission, combined with a dynamic source MAC rewriting mechanism and a monitoring/control system for load balancing and link failure detection, operates on wireless endpoints to manage multiple point-to-point wireless links between wired switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple wireless links are added to bridge between two Ethernet switches, then the aggregate data rate increases, but forwarding loops occur and switches shut down the ports
Solution Approach 1:
The patent segments the wireless link aggregation problem into two independent components: (1) a control plane mechanism using hash function-based destination MAC address mapping to prevent forwarding loops, and (2) a data plane mechanism using dynamic source MAC address rewriting to enable load balancing. This segmentation allows each component to address specific aspects of the problem without interfering with the other, resolving the contradiction between increasing data rate and preventing forwarding loops.
Solution Approach 2:
The patent introduces an intermediary mechanism - a hash function-based mapping table at the wireless link endpoints - that acts as a mediator between the multiple wireless links and the Ethernet switches. This intermediary controls frame forwarding decisions, ensuring that frames are distributed across links without creating loops, while still allowing aggregate bandwidth to increase. The intermediary resolves the conflict by providing intelligent frame steering without requiring switch port shutdowns.
2Productivity
If standard Ethernet link aggregation is implemented over wireless links, then multiple ports can be configured into a link aggregation group, but load balancing becomes ineffective due to RF condition fluctuations
Solution Approach 1:
The patent implements dynamic source MAC address rewriting at the wireless link endpoints, where the source MAC address in transmitted frames is dynamically changed based on which wireless link is being used. This dynamic adaptation allows the system to respond to real-time RF conditions and link quality variations, continuously optimizing load distribution across available links. The dynamic nature of the MAC rewriting mechanism enables the system to adapt to changing wireless conditions, maintaining effective load balancing and high throughput despite RF fluctuations.
3Reliability
If control packets are sent on each wireless link to detect link failure, then link failure detection is implemented, but false detections occur due to frame drops from poor RF conditions
Solution Approach 1:
The patent applies preliminary action by implementing hash function-based destination MAC address mapping before frames are transmitted over wireless links. This pre-established mapping relationship creates an inherent accountability mechanism where each destination MAC is assigned to specific link(s) in advance. When combined with dynamic source MAC rewriting, this preliminary action enables more accurate failure detection - if a frame destined for a particular MAC address fails to arrive, the system can determine whether the failure is due to link issues or normal wireless frame drops, reducing false detections while maintaining reliable link failure detection capability.
Data Source
AI summary
Extending wired networks by aggregating multiple wireless links. Multiple wireless links are used to bridge wired networks, such as wired Ethernet networks. Each wireless link applies a hash function to the destination MAC address of presented traffic and uses the result of the hash function to determine if the traffic is passed by that wireless link or is dropped. For broadcast and multicast frames, the hash function is calculated on the source MAC address. Dynamic source MAC rewriting may be performed to prevent port flapping or out-of-order arrival of frames. Establishing one link as a master and communicating among links allows for load balancing and link failure detection.