Network Switch VLAN Encapsulation for Time-Critical Data Paths
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing industrial automation systems face challenges in efficiently transmitting time-critical data due to issues with resource allocation and prioritization, leading to potential data loss and network malfunctions, especially when transitioning through transit networks.
Innovation Solution
A method and network switch design that encapsulates datagrams with virtual local network identifiers and priority specifications, allowing transparent transmission through a third sub-network with reserved resources, ensuring low latency and maintaining prioritization across sub-networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data frames with real-time requirements are transmitted through a transit network sharing bandwidth with other data streams, then network resource utilization is improved, but the quality of service and delivery timing of time-critical data frames deteriorate
Solution Approach 1:
The network is segmented into different virtual channels (VC0, VC1, VC2) within the transit network switch, where each channel is dedicated to specific types of traffic. Time-critical control data is assigned to a dedicated virtual channel with guaranteed bandwidth, while other data streams use separate channels. This segmentation ensures that time-critical data maintains its quality of service while the overall network utilizes multiple channels for higher total throughput.
2Reliability
If bandwidth reservation is implemented for audio and video data streams with highest priority, then quality of service for these streams is improved, but the flexibility and network configuration complexity worsen
Solution Approach 1:
The transit network switch is designed with multi-functionality to handle both bandwidth-reserved audio/video streams and time-critical control data simultaneously through different virtual channels. The same switch infrastructure supports multiple QoS mechanisms including credit-based shaping for audio/video and dedicated virtual channels for control data, eliminating the need for separate specialized devices and reducing overall system complexity.
3Reliability
If Credit-based Shapers are used to limit bandwidth for audio/video streams, then quality of service is improved, but transmission pauses are introduced that are problematic for control data bundles
Solution Approach 1:
Different QoS mechanisms are applied locally to different types of traffic within the same transit network switch. Credit-based shapers are applied to audio/video channels to enforce bandwidth limits, while time-critical control data channels use a different mechanism with guaranteed bandwidth and no forced pauses. This local differentiation allows each traffic type to receive the appropriate treatment for its specific requirements without negatively impacting other traffic types.
4Reliability
If prioritized transmission is implemented using VLAN tags, then quality of service for prioritized data is improved, but loss of prioritization information occurs when data passes through transit networks
Solution Approach 1:
The transit network switch acts as an intermediary that preserves prioritization information by mapping incoming VLAN tags to appropriate virtual channels based on predefined rules. When control data frames with prioritization information enter the transit network, the switch translates the VLAN tags into virtual channel identifiers that maintain the priority levels throughout the transit network. This intermediary function ensures that prioritization information is not lost even though the data passes through the transit network infrastructure.
Data Source
AI summary
Method for operating a communication system for transmitting time-critical data, wherein the datagrams are forwarded from a first communication device to a first network switch based on an identifier of a first virtual local network and a priority specification, where the first network switch encapsulates the datagrams sent by the first communication device in respective data frames, which are assigned to a data stream through a third sub-network, and inserts an identifier of a second virtual local network into the data frames, resources along a selected path are reserved in the third sub-network based on the identifier of the second virtual local network and a second network switch removes the datagrams encapsulated in the data frames assigned to the data stream from the received data frames and forwards the removed datagrams to a second communication device based on the identifier of the first virtual local network and the priority specification.