Deterministic Avionic Network Interface for Collision-Free UDP Communication
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Solution Overview
Problem
Conventional network interfaces and protocols fail to meet the stringent safety and high-bandwidth requirements of avionics applications, particularly in providing deterministic communication for latency, jitter, bandwidth, and data integrity.
Innovation Solution
A deterministic network interface using Ethernet-compatible protocols and hardware, with a programmable configuration area for static IP and MAC address management, error detection, and time-deterministic data transfer, configured for connection with a host system and two Ethernet physical media, and arranged in a ring topology for collision-free communication using UDP packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional Ethernet network interfaces are used, then hardware availability and ease of implementation are improved, but communication reliability and determinism deteriorate
Solution Approach 1:
The network interface is divided into distinct functional layers (Physical layer, MAC layer, IP layer, UDP layer) with independent error detection and handling mechanisms at each layer. This segmentation allows conventional Ethernet hardware to be used while implementing deterministic communication through controlled processing at each segment.
Solution Approach 2:
Static IP and MAC address tables are pre-configured in the programmable configuration area before runtime operation. This preliminary configuration eliminates address resolution delays and ensures deterministic packet routing from the outset, while maintaining compatibility with standard Ethernet hardware.
2Reliability
If bespoke data buses and protocols are developed for aircrafts, then communication reliability is improved, but bandwidth capability and cost deteriorate
Solution Approach 1:
The network interface implements universal Ethernet-compatible protocols while adding avionics-specific deterministic communication capabilities. The same hardware can serve both conventional Ethernet functionality and safety-critical avionics communication, eliminating the need for separate bespoke data buses.
Solution Approach 2:
The interface dynamically adjusts transmission parameters including packet size, transmission timing, and error detection thresholds based on network conditions and safety requirements. This allows optimization of both reliability and bandwidth utilization without requiring dedicated physical infrastructure.
3Loss of time
If deterministic communication mechanisms are implemented, then latency and jitter control are improved, but device complexity increases
Solution Approach 1:
A programmable configuration area with address tables serves as an intermediary between the physical Ethernet interface and the higher protocol layers. This intermediary structure simplifies deterministic routing by pre-resolving addresses and managing packet forwarding decisions, reducing the complexity burden on the main processing system.
Solution Approach 2:
The network interface implements autonomous error detection and packet forwarding decisions based on pre-configured tables and real-time conditions. The Media Access Control layer independently manages collision detection and packet transmission timing without requiring continuous host system intervention, reducing overall system complexity while maintaining determinism.
4Reliability
If error detection mechanisms are added, then data integrity is improved, but processing time and overhead increase
Solution Approach 1:
The error detection process is optimized by skipping unnecessary verification steps when conditions permit. The Media Access Control layer rapidly detects and discards corrupted packets without full protocol processing, while valid packets proceed through streamlined verification at higher layers, minimizing overall processing time while maintaining integrity.
Solution Approach 2:
Error detection parameters and validation rules are pre-configured in the programmable configuration area. This preliminary setup enables rapid comparison and validation during packet processing, eliminating the need for complex runtime error analysis and reducing processing overhead while ensuring data integrity.
Data Source
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Figure 3
AI summary
Deterministic network interface for an avionic network, configured for two Ethernet physical media with two neighbouring network interfaces MAC#0, MAC#2. The network interface of the invention allows the realization of ring-topology network without collision in the physical Ethernet media. The communication between nodes is carried out in a fully deterministic fashion by an unconnected (UDP) protocol. The network interface is configured for connection with one host system, represented by a CPU 55 and a memory 60, through a host interface 145, a bridge interface 150, and a high speed link 170. The interface comprises a Media Access Control layer 20, operatively arranged for receiving and transmitting data from and to said two neighbouring network interfaces, and for receiving and transmitting data from and to the host system, wherein a programmable configuration area 80 inserts and/or recognizes IP and/or MAC addresses in the Ethernet packets based on an address table stored in the configuration area 80.The UDP layer 40 implements in particular the encapsulation of the messages received from the host system into valid UDP datagrams, and the extraction of the message from the datagrams received from the hierarchically lower layers 20, 30. Importantly, these operations are autonomously executed in the network interface and are time-deterministic, in the sense that the passage through the UDP layer, in either direction, does not introduce any unforeseeable delay. The UDP layer may use information stored in the parameter area 80, for example in coding and decoding the UDP ports.The interface of the invention also incorporates a hardware end-to-end integrity mechanism that ensures message integrity from the memory of the sender host to that of the recipient one. When a message 14 to be transmitted is composed in the memory 60 of the host, an error-detecting code 15 is computed and associated to the message. The error-detecting code can be for example a CRC. The message is then sent towards the network interface through all the various links and buffers, and descends the protocol stack to the MAC layer 20. When the message is received in the network interface, the error detecting code 15 is verified and stripped from the message. If the verification of the CRC code 15 fails, the message 14 has been altered in the passage from the host system to the network interface, and the network interface can be programmed to take corrective or remedial actions.