If you want point-to-point communication between two network namespaces, you should use veths[1]. I think virtual patch cables is a good mental model for veths.
If you want multiple participants, you use bridges, which are roughly analogous to switches.
If you want multiple participants, you use bridges, which are roughly analogous to switches.
[1] https://man7.org/linux/man-pages/man4/veth.4.html