Ethernet Port Table Flushing via Ring Segmentation
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Solution Overview
Problem
Existing Ethernet network protocols like RSTP and MSTP cause unnecessary overload and bandwidth requirements due to excessive MAC address flushing, leading to broadcast storms, as they remove more entries than necessary from the Filtering Database during topology changes.
Innovation Solution
The method identifies affected rings in an Ethernet network and flushes port tables only on those rings, using control signals to selectively flush designated or root port tables, reducing unnecessary signaling and overload by employing new topology change flags in BPDU messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If RSTP and MSTP use a single TC flag to indicate topology changes, then topology change notification is simple, but excessive MAC address flushing occurs causing broadcast storms and network overload
Solution Approach 1:
The patent segments the topology change notification by introducing two distinct flags (TC and RTTC) instead of using a single flag. This segmentation allows different types of topology changes to be notified separately, enabling selective MAC address flushing only where necessary, thus preventing unnecessary broadcast storms while maintaining simple notification mechanisms
Solution Approach 2:
The patent applies local quality by making the flushing behavior location-dependent and event-specific. Instead of blanket flushing across the entire network, the invention enables selective flushing based on the type of topology change detected, ensuring that only the necessary portions of the network perform flushing operations, thereby reducing overall network overload
2Reliability
If RSTP and MSTP remove MAC addresses from FDB during topology changes, then the Filtering Database remains accurate, but the re-learning process generates excessive broadcast traffic
Solution Approach 1:
The patent applies partial action by performing MAC address flushing only partially and selectively based on the specific topology change event. Instead of removing all MAC addresses from the FDB during any topology change, the invention removes only those addresses that are actually affected by the specific change, thereby maintaining FDB accuracy while minimizing the trigger for re-learning broadcast traffic
3Device complexity
If a single TC flag is used for topology change notification, then protocol simplicity is maintained, but bandwidth requirements increase due to excessive re-learning messages
Solution Approach 1:
The patent segments the topology change notification into two distinct flag types (TC and RTTC) to differentiate between regular topology changes and root topology changes. This segmentation enables receivers to understand the specific nature of the change and perform selective flushing operations, thereby reducing the number of re-learning messages needed and lowering overall bandwidth consumption while maintaining protocol simplicity
Data Source
AI summary
A method and apparatus for flushing port tables in an Ethernet network that includes a Root Bridge node (1) and a plurality of bridge nodes (2-7). A ring of bridge nodes affected by a change in the topology of the Ethernet network is identified from the plurality of, bridge nodes. The ring of bridge nodes (2-7) includes a branching bridge node (2) providing a connection to the Root Bridge node (1). Port tables are flushed only at the bridge nodes on the ring (2-7), rather than all of the bridge nodes in the Ethernet network, which greatly reduces the amount of signalling required during a relearning process.