How publish and subscribe works in Mesh network

[Bhavit Rajput]

I want to develop a mesh network where I can send/receive data from one device to other devices(sleepy sensors) through relay/router node (always on).

For example

A (Publish address: 0x001, Subscribed address: 0x002)

B and C (Relay node)

D and E (Publish address: 0x002, Subscribed address: 0x001)

In this case, A and is not in the range of D and E, so when it publishes data will it be received by D and E via B or C node?

Is there any specific parameters are there in APIs by which we can set the node as Relay of LPN?

[Mttrinh]

Hi,

In this case, A and is not in the range of D and E, so when it publishes data will it be received by D and E via B or C node?

Yes, the D and E node should receive the data published by node A, using node B or C as a relay.

Is there any specific parameters are there in APIs by which we can set the node as Relay of LPN?

The relay feature is enabled by default in our Light switch example.

Relay nodes are used to increase the range of communication throughout the mesh network by re-broadcasting received mesh messages. These nodes keep the radio running constantly, scanning for incoming advertising packets. 

The point with LPN is to decrease power consumption. The LPN establishes a special relationship, called friendship, with a neighboring Friend node that stores all the mesh messages. The LPN is in sleep mode most of the time, it wakes up periodically and polls the Friend node for any new messages. So LPN can't be relay nodes.

Have a look at this documentation for more info regarding Low Power Node feature.

[Mttrinh]

The Friend feature is supported in our latest Mesh SDK v4.1.0 and it is enabled in the light switch server example.

Note: That if you don't plan to use LPN then you won't need the Friend node. Have a look at this example if you intend to use LPN.

[Bhavit Rajput]

Thanks.

Is it possible to send/receive data through node's unique address or we can only use publish/subscribe method only.

[Mttrinh]

What do you mean by a unique address? You can publish directly to a node by publishing to their unicast address.

[Bhavit Rajput]

Ohh now I understood.