Using a backbone interface

[dakhnod]

What settings influence the usage of a backbone interface like Ethernet in the otbr-agent?

Here is my understanding of it:

• The BR can bridge to real interfaces, allowing traffic in both directions
• The BBR allows connecting multiple partitions, although I don't fully understand that
• Adding a trel:// URL allows using an interface to shorten the path within a partition using some backbone interface?

I would be happy to get some hints on what I got wrong!

Also, how can I make sure that packets get transmitted via Thread to a device that is also attached to Ethernet?

Thanks!

[jwhui]

One concept the backbone router mechanism supports is electing which border router serves to forward IPv6 multicast messages from the infrastructure link to the Thread network. This avoids having multiple backbone routers forwarding the same multicast message into the Thread network, and duplicate multicast transmissions that this will cause.

[dakhnod]

Thanks! Yet, how can I make sure that only thread is used for data transmission to a device, although an alternative link would be available?

[jwhui]

With TREL enabled, infrastructure links will be included as part of the Thread topology and Thread will determine shortest-path routes considering both 15.4 and TREL links.

If you are looking to disable TREL, you can disable the feature when building (see OPENTHREAD_CONFIG_RADIO_LINK_TREL_ENABLE).