Selective FDB Flush in Ethernet Ring Protection Switching
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Solution Overview
Problem
Ethernet ring protection switching (ERPS) networks face unnecessary message flooding and service outages due to indiscriminate flushing of filtering databases across the major ring in response to sub-ring topology changes, which is inefficient and wasteful.
Innovation Solution
Implementing a method to selectively flush filtering databases in the major ring by terminating topology change notifications and transmitting FDB flush messages only to interconnection nodes and nodes between them, thereby limiting the flush to affected areas and preventing unnecessary message propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If topology change notification is propagated across the entire major ring, then all nodes can be informed of the topology change, but unnecessary message flooding occurs and causes service outages on the major ring
Solution Approach 1:
The patent applies local quality by differentiating the treatment of topology change notifications based on the node's position in the network. Instead of uniformly propagating TCNs across all major ring nodes, the system selectively terminates TCNs at interconnection nodes and generates FDB flush messages only for nodes between interconnection nodes. This localized approach ensures that only affected nodes receive flush messages, eliminating unnecessary message flooding while maintaining reliable topology change notification for relevant nodes.
2Reliability
If filtering database is flushed at all major ring nodes, then loop avoidance is ensured, but network efficiency deteriorates due to unnecessary flush operations
Solution Approach 1:
The patent segments the major ring network into distinct segments based on interconnection nodes. Each segment between two interconnection nodes is independently managed for FDB flushing. When a sub-ring topology change occurs, only the specific segment containing the change is identified and flushed, rather than flushing the entire major ring. This segmentation maintains loop avoidance reliability within affected segments while significantly improving network efficiency by avoiding unnecessary flush operations in unaffected segments.
3Loss of energy
If topology change notification is terminated at interconnection node, then message propagation is limited, but selective FDB flushing must be implemented
Solution Approach 1:
The patent applies preliminary action by pre-configuring interconnection nodes with knowledge of their positions and the topology structure. When a TCN is received, the interconnection node immediately terminates it and generates FDB flush messages directed only to nodes between interconnection nodes, based on pre-established routing information. This preliminary configuration allows the system to limit message propagation overhead while implementing selective FDB flushing without adding complex real-time decision logic during message processing.
Data Source
AI summary
Methods and systems to operate an Ethernet ring protection switching (ERPS) network. In one embodiment, a method performed by a network device in the ERPS network device is disclosed. The ERPS network comprises a major ring and a sub-ring, where the network device is a first interconnection network device that is on both major ring and sub-ring. The method comprises determining that a topology change notification is received from the sub-ring, identifying a link that is coupled to the network device and that is towards a second interconnection network device, where the second interconnection network device is also on both major ring and sub-ring. The method further comprises terminating the topology change notification and transmitting a first message using the link towards the second interconnection network device, where the first message is a filtering database (FDB) flush message.