UDP WAN Transport for DDS NAT Traversal
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Solution Overview
Problem
Current solutions for wide-area network connectivity, such as Connext DDS, face challenges with Network Address Translation (NAT) traversal, especially with symmetric NATs, and require complex configurations for TCP transport, which leads to high latency and scalability issues in autonomous vehicle applications.
Innovation Solution
A method for communicating Object Management Group (OMG) Data Distribution Service (DDS) Participants using the Real-Time Publish Subscribe (RTPS) wire protocol over wide area networks, addressing NAT traversal, IP address changes, and efficient bandwidth utilization by employing a UDP-based solution with a Locator Resolution Service and Relay Service to establish and maintain NAT bindings and public IP addresses dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP transport in asymmetric mode is used to traverse NAT, then connectivity is established, but configuration complexity increases and latency increases
Solution Approach 1:
The patent introduces a rendezvous server as an intermediary that facilitates NAT traversal without requiring complex TCP configurations. The server acts as a mediator to establish connections between peers behind NAT, using a simplified protocol that avoids the 60+ configuration parameters required by traditional TCP asymmetric mode while maintaining reliable connectivity.
2Reliability
If TCP transport in asymmetric mode is used to traverse NAT, then connectivity is established, but latency increases
Solution Approach 1:
The rendezvous server enables direct peer-to-peer UDP connections by mediating the initial connection setup. Once connected, data flows directly between peers without TCP overhead, achieving latency comparable to symmetric NAT scenarios while maintaining connectivity through asymmetric NAT, thus resolving the latency penalty associated with TCP asymmetric mode.
3Loss of time
If Peer-to-Peer WAN Transport based on UDP using hole punching is used, then latency is reduced, but compatibility with symmetric NAT is lost
Solution Approach 1:
The patent implements a dynamic connection establishment mechanism that adapts to different NAT types. The system can operate in direct mode for asymmetric NAT (low latency) and automatically switch to relay mode through the rendezvous server for symmetric NAT, providing both low latency performance and universal NAT compatibility without requiring predetermined NAT type classification.
4Reliability
If existing WAN Transport solution is used, then peer-to-peer communication is enabled, but interoperability with public STUN servers is lost
Solution Approach 1:
The patent implements a universal rendezvous server that can function both as a private proprietary server and as a public STUN-compatible server. The server supports multiple protocols including standard STUN, allowing existing public STUN servers to be utilized without modification while maintaining the ability to operate private servers for enhanced security and control, thus achieving both peer-to-peer reliability and public interoperability.
Data Source
AI summary
Object Management Group (OMG) Data Distribution Service (DDS) DomainParticipants communication methods and system are provided using the Real-Time Publish Subscribe (RTPS) wire protocol over one or more wide area networks (WAN). Three main issues are addressed: Network Address Translation traversal, Changes in IP addresses, and Efficient bandwidth utilization. Embodiments lead to a scalable solution for WAN Connectivity of DDS Applications using RTPS Wire Protocol. This is a connectionless solution that works on top of UDP as the IP transport. The key benefits of this solution are: Low latency communication with reliable and best-effort data delivery, Minimal data loss when moving across networks, including firewalls/NATs, Minimal migration impact for existing applications. No changes to the API, and Scalability using UDP versus legacy TCP solution. A new UDP WAN transport avoids connection-based overhead inherent in TCP, which becomes increasingly problematic as the number of communication endpoints increases.