Border router vs BBR

[dakhnod]

The way I understand it, a border allows routing packets from an ethernet network to a thread network by bridging the two.

Following that logic, I have a question about two different Thread partitions:

A thread device sends a packet from Thread partition A, addressing a device inside partition B.

The border router from A should forward the packet to the connecting Ethernet network, where it should get routed to Border router B, and then to the device inside B.

So, according to my logic, a BBR should not be needed, since both border routers (A and B) handle the briding automatically, right?

What benefits would a BBR bring in that case?

Thanks for your time!

[jwhui]

So, according to my logic, a BBR should not be needed, since both border routers (A and B) handle the briding automatically, right?

Yes, correct. The backbone concept is not required for devices in two different Thread networks / partitions to send messages to each other over an infrastructure link. In this case, the two Thread partitions / networks will have different IPv6 prefixes.

What benefits would a BBR bring in that case?

The original intent of the backbone router concept is to allow multiple Thread networks to be organized into a single Thread domain. All Thread networks in the same Thread Domain are assigned the same IPv6 prefix, allowing devices to move between different Thread networks while maintaining the same IPv6 address. However, this pushes the complexity of routing to different Thread networks to other parts of the network layer. AFAIK, the Thread Domain concept really hasn't been deployed in practice.