Multi-homing MAC Table Stability in TRILL Overlay Networks
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Solution Overview
Problem
In multi-homing access overlay networks, the frequent 'flip-flop' of MAC table entries due to multiple ingress RBridges causing instability and packet loss, particularly in TRILL and SPB networks, where the same MAC address is mapped to different overlay network device identifiers, leading to disordered return flows and packet loss.
Innovation Solution
A message processing method that sets an identifier for multi-homing access in overlay encapsulation, allowing the far-end edge device to store and manage mapping relationships between a single MAC address and multiple overlay network device identifiers, preventing the flip-flop issue by using reserved fields or TLVs to carry link aggregation group information, enabling load balancing and stable communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the same MAC address is mapped to multiple overlay network device identifiers in multi-homing access, then load balancing capability is improved, but MAC table entry stability deteriorates due to frequent flip-flop
Solution Approach 1:
The patent segments the MAC address table into two distinct types: traditional one-to-one MAC-to-device mappings and multi-homing MAC-to-multiple-device mappings. This segmentation allows the system to maintain stable one-to-one mappings for normal traffic while enabling load balancing through multiple devices for multi-homing scenarios, thus resolving the contradiction between load balancing capability and MAC table stability.
Solution Approach 2:
The patent introduces an intermediary mechanism (the multi-homing identification flag and associated processing logic) that mediates between the conflicting requirements. When a MAC address is identified as multi-homing, the system activates special handling that allows multiple device identifier mappings without causing flip-flop, while non-multi-homing MACs continue to use traditional stable mappings.
2Stability of the object's composition
If traditional one-to-one MAC mapping is used, then MAC table stability is maintained, but load balancing capability is lost in multi-homing scenarios
Solution Approach 1:
The patent makes the MAC address table dynamic by allowing the mapping relationship to change based on the multi-homing identification flag. For multi-homing MAC addresses, the system dynamically maintains multiple device identifier mappings and can flexibly select among them for load balancing, while maintaining stability for non-multi-homing MACs through traditional mappings.
Solution Approach 2:
The patent changes the parameter of MAC-to-device mapping from fixed one-to-one to flexible one-to-many for multi-homing scenarios. By detecting the multi-homing status and adjusting the mapping parameter accordingly, the system achieves both stability for normal MACs and load balancing capability for multi-homing MACs.
3Productivity
If multiple ingress RBridges are used for multi-homing access, then network redundancy and load balancing are improved, but packet loss occurs due to disordered return flows
Solution Approach 1:
The patent implements a feedback mechanism where the egress RBridge monitors incoming MAC addresses and identifies multi-homing patterns. Based on this feedback, the system adjusts its forwarding behavior to maintain consistent return flow paths for multi-homing traffic, preventing disordered returns and packet loss while preserving the benefits of multiple ingress paths.
Solution Approach 2:
The patent performs preliminary identification and marking of multi-homing MAC addresses before forwarding decisions are made. By pre-identifying multi-homing traffic and establishing appropriate mapping relationships in advance, the system ensures that return flows are properly routed without disorganization, preventing packet loss while maintaining network redundancy.
Data Source
AI summary
A message processing method in a multi-homing access overlay network, comprising: when an edge device receives a data message from a multi-homing access bound interface, setting an identifier indicating that the data message is from multi-homing access in the overlay encapsulation performed on the data message, and sending the data message after the overlay encapsulation to the overlay network.