RDMA NIC Traffic Shaping for Bounded-Latency Vehicle Control
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Solution Overview
Problem
Existing RDMA technologies, primarily developed for data centers, are not suitable for vehicle networks requiring ultra-low latencies and lossless transmission of critical traffic, as they fail to guarantee bounded latency and are incompatible with Converged Ethernet and time-sensitive networking protocols.
Innovation Solution
Integrate TSN traffic shapers with RDMA NIC hardware to configure egress queues and calculate committed information rate (CIR) and committed burst size (CBS) to ensure lossless RDMA data exchanges with bounded latencies, using asynchronous traffic shapers (ATS) to prioritize critical traffic (CT) and manage egress queues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If RDMA is used for data center applications, then processor load is reduced and communication latency is reduced, but bounded latency guarantee is not provided for critical traffic
Solution Approach 1:
The patent segments network traffic into different priority classes, with critical traffic (CT) separated from best-effort traffic. Egress queues are divided into CT queues and non-CT queues, allowing CT to be handled with special traffic shaping guarantees while other traffic uses standard scheduling. This segmentation enables bounded latency guarantees for CT without sacrificing overall system throughput.
Solution Approach 2:
The patent implements preliminary configuration of traffic shapers with predetermined committed information rates (CIR) and committed burst sizes (CBS) for critical traffic queues. By pre-calculating and setting these parameters before traffic arrival, the system ensures that CT frames will always have guaranteed bandwidth and bounded latency without requiring real-time decisions that could introduce uncertainty.
2Adaptability or versatility
If conventional Ethernet switching is used in vehicle networks, then device compatibility is maintained, but ultra-low latency and lossless transmission are not achieved
Solution Approach 1:
The patent introduces traffic shapers as intermediary devices between the Ethernet switch and the RDMA NIC. These traffic shapers act as mediators that implement TSN protocols and lossless transmission guarantees at the egress queue level, while maintaining standard Ethernet compatibility at the physical layer. This intermediary approach enables advanced QoS features without requiring changes to the underlying Ethernet infrastructure.
Solution Approach 2:
The patent changes the operational parameters of egress queues by configuring them with specific traffic shaping parameters (CIR, CBS, and queue lengths) that guarantee lossless transmission for critical traffic. By adjusting these parameters, the system transforms conventional Ethernet switching behavior to provide TSN-compliant lossless Ethernet functionality while maintaining hardware compatibility.
3Productivity
If multiple classes of data are transmitted through shared egress queues, then bandwidth utilization is improved, but latency bounding for critical traffic cannot be guaranteed
Solution Approach 1:
The patent segments egress queues into dedicated CT queues and non-CT queues, preventing mixed traffic from interfering with critical traffic timing. Each CT queue is independently traffic-shaped with guaranteed CIR, ensuring that CT bandwidth is reserved and latency is bounded even when other queues are actively transmitting data.
Solution Approach 2:
The patent implements feedback mechanisms through traffic shapers that monitor queue lengths and transmission rates. The traffic shapers continuously adjust the transmission of CT frames based on current network conditions while maintaining the predetermined CIR guarantee, providing dynamic feedback control that ensures both bandwidth efficiency and latency bounds.
Data Source
AI summary
In an aspect, systems and methods of connected nodes, including electronic control units (ECUs) in a vehicle, integrate remote direct memory access (RDMA) capabilities with time-sensitive networking (TSN) traffic shaper configurations in a manner that guarantees lossless, bounded-latency critical traffic (CT) streams, while also allowing for different classes of traffic to flow through the connected nodes. In another aspect, mechanisms are introduced to enable an automotive software framework (e.g., classic AUTOSAR) to support RDMA communications.