ROS2 / DDS Visibility of Topics/Nodes

asked 2020-08-27 15:09:56 -0600

Whiskeyjack gravatar image


I have tried running ROS2 Foxy on three machines:

  • Machines A and B were connected to same LAN
  • Machines B and C were connected via a VPN (both were clients)

How they were connected is (I guess) irrelevant, but just in case. Running the demo chatter node in Machine C made it only visible in Machine B (as expected). However, after echoing the data in Machine B, the node and the topic became visible to Machine A. Machine A, nonetheless, was unable to echo the topic.

This reminds me a bit of multi-machine connection in ROS1, when multiple machines would be connected to the same ROS master but if ROS_IP was not properly configured in each machine, then the topics would be visible but data would not be accessible.

My question is, is this the expected behavior? Is it normal than A can see what topics C is publishing only when those are consumed by B? I guess this might be a question entirely about DDS.

Best, J.

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