VLAN Pruning in STP Ethernet Networks
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Solution Overview
Problem
Ethernet networks supporting VLANs and utilizing the Spanning Tree Protocol experience excessive broadcast traffic during and after topology changes, leading to inefficient use of network bandwidth due to the recalculation of the STP tree structure and deletion of Filtering Database information.
Innovation Solution
A method is introduced to prune the broadcast domain of VLANs by transmitting de-activation messages between Ethernet switching nodes, identifying and de-activating redundant ports, thereby creating VLAN-related sub-trees that only allow broadcast traffic within the necessary paths, reducing unnecessary data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If STP recalculates the active topology in case of faults or reconfiguration, then the network topology is updated to maintain loop prevention, but excessive broadcast traffic is generated during the recalculation process
Solution Approach 1:
The patent segments the VLAN broadcast domain into multiple STP trees, each handling specific VLANs. By dividing the broadcast domain, broadcast traffic is confined to smaller segments rather than flooding the entire network, thus reducing overall bandwidth consumption while maintaining topology stability.
Solution Approach 2:
The patent applies different STP tree configurations to different VLANs based on their specific requirements. Each VLAN can have optimized broadcast domain boundaries, allowing local optimization of broadcast traffic containment while maintaining overall network reliability.
2Reliability
If STP determines the active topology upon initialization, then the network is protected from loops, but excessive broadcast traffic occurs during the initialization learning process
Solution Approach 1:
The patent performs preliminary actions by pre-configuring VLAN assignments to specific STP trees before full network operation begins. This allows the network to skip part of the learning process during initialization, as MAC address tables can be pre-populated based on known VLAN-to-STP-tree mappings, reducing convergence time while maintaining loop prevention.
3Extent of automation
If GVRP dynamically registers VLANs on a per VLAN basis, then VLAN provisioning is automated, but broadcast traffic increases due to VLAN registration messages
Solution Approach 1:
The patent extracts VLAN registration traffic from the global broadcast domain by confining GVRP messages to specific STP trees. This extraction reduces the scope of broadcast traffic for VLAN provisioning, allowing automation to be maintained while minimizing bandwidth consumption.
Data Source
AI summary
A method for utilizing a Spanning Tree Protocol (STP) in an Ethernet network wherein a number of VLANs are defined and a plurality of Ethernet switching nodes (A, B, C D E, F,G H) are interconnected via their ports (A1, . . . ,H4) so that each of the ports is initially assigned to one or more VLANs, and each of the VLANs is intended to enable traffic between two or more edge ports (D3, B3). The method comprises a so-called pruning procedure initiated upon establishing a new STP topology (30) related to one or more VLANs. This procedure concerns a broadcast domain of at least one of the VLANs and is aimed at obtaining a sub-tree for each pruned VLAN in the new STP topology. The sub-tree is usually shrunk, bound by the edge ports assigned to the corresponding pruned VLAN, and thus eliminates broadcast traffic of the pruned VLAN to any Ethernet switch extending beyond the obtained sub-tree.