ROS Cross-Distribution Communication

Just out of curiosity, I happened to check ROS cross-distribution communication.
Topic and Services are confirmed using latest container with host network.

ROS 1

Scenario	ROS Master	Can communicate?
kinetic/melodic	kinetic	YES
melodic/noetic	kinetic	YES
noetic/kinetic	kinetic	YES
kinetic/melodic	melodic	YES
melodic/noetic	melodic	YES
noetic/kinetic	melodic	YES
kinetic/melodic	noetic	YES
melodic/noetic	noetic	YES
noetic/kinetic	noetic	YES

• ros-ROSDISTRO-roscpp-tutorials package is used for verification.

ROS 2 (Updated)

Scenario	Can communicate?
foxy/galactic	YES
galactic/rolling(humble)	YES
rolling(humble)/foxy	YES

• export RMW_IMPLEMENTATION=rmw_fastrtps_cpp is enabled always to specify rmw implementation.
• export ROS_DOMAIN_ID=5 is specified.
• docker command docker run -it --privileged --name ros2_distro ros:distro. (need to replace distro into foxy, galactic, humble and rolling)
• Bind different IPC namespace and network interface to each container. (no argument --net=host nor --ipc=host to docker command.)

might be dependent on rmw implementation, but cross-distribution communication is not supported as official, see https://answers.ros.org/question/341372/can-nodes-from-different-ros-2-distributions-communicate-compatibly/.