Why adding All-nodes to subscription list is prohibited?

[choehyunho]

Hi everyone,

During test with my small mesh network, I found that adding all-nodes to subscription list is prohibited by Mesh Specification.

In Mesh Profile 4.3.2.19,

The value of the Address field shall not be an unassigned address, unicast address, all-nodes address or virtual address.

Anyone knows why this prohibition is required?

Is there any other possible problem, like security issue or something?

[Mttrinh]

Hi,

The all nodes address is a fixed group address(0xFFFF), which is why you shouldn't add it to the subscription list. You can publish to all the nodes by publishing to this group address without needing to add it to the subscription list. Have a look at this under "Group Address".

[choehyunho]

Yes, this is what I expected, but actually it does not work.

The following is my test case:

1. There are three nodes, two nodes have server model, and the last node has client model.

2. I set publication address as all-nodes(0xFFFF), and publish interval as 10 seconds for two server nodes.

In my understanding, the third node(client node) should receive the message without adding subscription list, but not.

When I made a new group, and set publication address to that group in server model, and set subscription list to that group in client model, the message sent and received well.

Mttrinh, can you check about this behaviour?

[choehyunho]

Oh, I just read Mesh Profile section 3.4.2.

It mentions that only the primary model shall process fixed group address.

I will put my models in first element and test again.

[choehyunho]

I just confirmed that the root element successfully received the broadcast messages to all nodes.

Thank you for clarifying about the spec.