RSTP Domain Separation via Hidden VLAN IDs
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Solution Overview
Problem
Existing Rapid Spanning Tree Protocol (RSTP) solutions are insufficient for mission-critical infrastructure networks, particularly in large L2 networks, as they lack effective domain separation, scalability, fault isolation, and efficient re-convergence times, leading to potential network instability and downtime.
Innovation Solution
Implementing domain separation within the same L2 network using hidden VLANs as RSTP domain IDs and creating multiple redundant protocol control domains over HSR ring topologies, with HSR-DS devices managing network control planes to isolate faults and maintain L2 connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single RSTP domain is used across the entire L2 network, then network simplicity is maintained, but fault isolation and scalability are poor
Solution Approach 1:
The patent divides the L2 network into multiple independent RSTP domains using domain separation identifiers (DS-IDs). Each domain operates independently with its own RSTP instance, allowing faults to be contained within specific domains while maintaining overall network functionality. This segmentation enables better fault isolation and scalability without requiring complete network redesign.
2Reliability
If multiple RSTP domains are implemented for better fault isolation, then reliability improves, but network complexity increases
Solution Approach 1:
The patent introduces domain separation identifiers (DS-IDs) as intermediary elements that enable multiple RSTP domains to coexist on the same physical L2 network. These DS-IDs act as mediators that allow switches to distinguish between different RSTP domains and process RSTP messages appropriately, reducing the complexity of configuring and managing multiple physical networks while maintaining the benefits of domain separation.
3Loss of time
If traditional RSTP is used without domain separation, then configuration is simple, but re-convergence time during topology changes is slow
Solution Approach 1:
By segmenting the network into multiple RSTP domains using DS-IDs, the patent reduces the scope of topology change propagation. When a topology change occurs in one domain, only that specific domain needs to re-converge rather than the entire network. This segmentation significantly reduces re-convergence time while the domain separation mechanism manages the additional complexity through standardized protocols.
4Adaptability or versatility
If a large single L2 network is maintained, then network unity is preserved, but scalability and performance degrade
Solution Approach 1:
The patent enables large L2 networks to scale by dividing them into multiple manageable RSTP domains. Each domain can be independently configured, managed, and optimized, allowing the overall network to grow without proportionally increasing complexity. The domain separation mechanism maintains network unity through standardized interfaces while enabling independent evolution of individual domains.
Data Source
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AI summary
A method and system for keeping the control plane of a first ring network and one or more second RSTP networks separate on Layer 2while the data plane of the first and second networks integrated, by using a domain separation logic function in network devices connecting the second networks to the first ring network. The network device tags the BPDUs (bridge protocol data units) received from the second networks with an identifier before releasing to the first ring network, or remove the identifier from the BPDU received from the first ring network before releasing to the corresponding second network if the identifier in the BPDU matches the one associated with that second network. The identifier can be a hidden VLAN ID, a tag within the BPDU frame or a tag added to the control frame all to represent the control domain ID.