Difference Friend node and Relay nodes

RE: Difference Friend node and Relay nodes

Senchoi — Wed, 27 Jul 2022 10:30:11 GMT

can LPN nodes send messages to other nodes beyond and through the friend node? Those materials talks about LPN nodes receiving msgs from friend nodes but not the other way around.

RE: Difference Friend node and Relay nodes

Amanda Hsieh — Wed, 01 Sep 2021 09:53:53 GMT

Hi Sam,

When the project is built with the Friend feature in it, but the Friend feature is not enabled (or it has been disabled) runtime, then I would not expect any noticeable difference. If the project is not built with the Friendship feature at all, then I would expect some Flash and RAM savings.

For any Low Power Nodes in a Friendship, that would mean some more TX (instead of RX) and packet handling (CPU usage).

Regards,
Amanda

RE: Difference Friend node and Relay nodes

SamTheMan — Tue, 31 Aug 2021 12:21:48 GMT

Hi Amanda,

The backbone of my Bluetooth Mesh network consists of Friend nodes loaded with the "Light Switch Server Example".

Some of these nodes however are only really used as extenders, but don't have any Low Power Nodes attached to them yet in my current topology.

Would there be a benefit to disabling the friend feature on them as it's unneeded for my current setup? (example: power consumption etc.).

Regards,

Sam

RE: Difference Friend node and Relay nodes

Amanda Hsieh — Tue, 31 Aug 2021 11:44:25 GMT

Hi,

The Friend feature and the Low Power feature combines to provide low power message reception for the Low Power Node. (TX from the Low Power Node uses the standard protocol of sending normal ADV bearer packets.)

The relay feature makes the node retransmit messages over the advertising bearer. (Mostly affects the network / bearer layers.)

For the short story about layers and concepts, see Bluetooth mesh concepts.

For the full specification, see the Mesh Profile Specification from bluetooth.com, where the features are specified.

I suggest you go through these documentations:

Bluetooth Mesh Network: Friendship

Low Power node feature

Integrating Low Power node feature

Low Power node example

You will get a better understanding of Relay, LPNs and Friendship nodes and how things work between them.

Regards,
Amanda