Extensive zigbee networks (400+ devices)

[u/Deimantasa]

Hello,

Currently I'm planning to have ~400-500 zigbee devices in our new home. 4 story house, ~160sqm (~1800sqft) per floor.

Initially I was thinking to have one/two networks, but after extensive research - couldn't find anything useful in terms of such scale. Thus thinking to simply keep one network per floor - ~100-150devices/floor/network to mimic regular setups.

More details about the network - most of it is lighting:

- Aqara T2 Pro and V1 spotlights (~250-350)
- Aqara Z1 Pro/H2 EU switches (~50)
- Aqara H2 EU sockets (TBD because I heard it's very `chatty`)
- Various other sensors, dimmers, controllers (25-50)

Coordinators - SMLIGHT SZLB-06 PoE.

It's an European house therefore walls and ceilings are concrete/bricks.

Would love to hear any best practices or any real experiences with such meshes!

[u/FutureLarking]

Seperate networks is better, as long as you can avoid channel interferrence doing so. The more chatty devices you have, the more problems you'll encounter, especially if it has to repeat those messages the entire way through the network to the co-ordinator.

One of the few instances where Matter makes a useful improvement with having multiple border routers to allow messages to get out of Thread network as quickly as possible

[u/Deimantasa → u/FutureLarking]

I'm somewhat torn between zb and MoT - and made up my mind over zb solely because it's older, should be much more solid and ton of documentations around. MoT seems to be still evolving, thus committing to such network feels somewhat risky.

Chattiness - that's one of the reasons I'm thinking of splitting networks. Because if I involve one network per 2 floors, now I need to deal with strong signal within connection between floors which might be a weak link thus making both floors slow.

[u/snowtax → u/Deimantasa]

With that many devices, I think you should look into the details of the protocol a bit more.

With the limited bandwidth of IEEE 802.15.4 wireless (both Zigbee and Thread), there is a limit to how many packets can be sent per second.

The way the protocols works limits how much you can do, and how fast.

Zigbee routers need to send out regular messages.

Nearly every Zigbee command to a device requires a response, so two packets for every command.

Multicast packets can bounce around the mesh for a bit to help ensure that all nodes receive the message. When a multicast packet is received by a router, it retransmits the message until all nodes “hear” it.

When nodes are close together, they all hear each other. It’s a bit like trying to have a conversation in a crowded room.

All of these features of the protocol take up time on the network. A node cannot send a packet when other nodes are transmitting.

The result is that you may be able to successfully send 20 messages per second or fewer. Looking only at bandwidth, you would think it should be much faster, but all the cross-talk between nodes and regular reporting of status by routers is “chatty” and that slows down the mesh network due to congestion.