Mesh size limits

[ybuyankin]

Is there any theoretical limit for a number of nodes? So far I've found limits of 10 connections to AP, 15 layers max total, and an uint_16t number of nodes. Does that mean that a number of nodes in a single mesh could reach 64K?

Thanks,
--yuri

[ESP_LBB]

Hi ybuyankin,

Yes you are partly right.

There are 2 factors that will make difference:

1. Max layer: As you metioned 15 layers, but actually this can be set maximumly to 127 for now, as we use 1 byte to define this. However one hop can add up about 30ms of delay and the possibility of packet loss. So we recommend not to set this too large and should adjust it according to your scenario.

2. Max connection: This means the max connections for each node, which is also adjsutable. We have upstream flow control to assure all nodes can sent their message. If a parent node have 10 child nodes, it has to devide its memory into 10 parts, which will possibly cause lack of memory. By the way, our ESP32 can maxmumly support 16 connections.

So in conclusion, the theoritical limit of Mesh (on code level, with infinite memory resource) is way too large. But in actual application it depends on these two parameters that you set. If you set Max layer to 4, and Max connections to 5, then your Mesh network's theoritical limit is (1+5+5^2+5^3)=156.

Hope this can help, thanks.

[ybuyankin]

Thanks for the reply, very helpful. Two things to clarify:

You have mentioned packet loss possibility, does this mean not the actual data loss but the increased delay due to retransmissions?

And could you please estimate a practical limit and its parameters considering your knowledge of memory usage given delivery time is not too important?

[ESP_LBB]

Hi ybuyankin,

I'm not sure if I get the point of your question. Could you specify a little more?

For now we suggest 6 level and 6 connections for each node, normally it's enough.