this post was submitted on 21 Mar 2025
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Would you create a public channel that doesn't need vetting, posting its info publicly somewhere?
Would I personally? No. If you're posting the pre-shared key publicly, then might as well just use the default one.
What about topical channels if the mesh grows large, to hundreds or thousands of people? E.g. ask support questions in "Local Support" instead of "LongFast"
I do have my private channels named (with the exception of a single secondary channel called LongFast to be able to interact with the "default"/public mesh), but you can only have 7 (or is it 8?) channels per device; that's a hard limit of the firmware/protocol.
From what I've read, I think there's also an upper limit of around a hundred nodes per mesh.
Interesting. I guess it's a self-limiting problem. In effect LongFast would be limited by the number of nodes in your vicinity. Even in a large network, messages propagate to 3 hops so you won't be able to see messages from further away, even if the mesh has thousands more nodes further away.
This mesh doesn't seem to have 100-node limit. It seems to be a device limit where a device can only remember up to 100 nodes and it seems to be removing old ones as it discovers new ones.
The largest limitation with a lot of nodes is channel congestion. Despite the name, LongFast is still pretty slow. The more nodes you have the longer channels stay active when a message is sent. Not to mention all the telemetry packets being sent about.
My local area is nowhere near populated enough to cause an issue, but I've seen many recommendations that switching to ShortFast is the way to go when you have enough node density. It's around 10x faster so it can handle more traffic. While range is smaller the higher number of nodes in your area would help offset the drawbacks.
The issue then is you're no longer on the default setting of all factory meshtastic devices so no one visiting your area would be able to see your mesh. The only way around this I know of is if you're putting key locations on the mqtt meshmap where it shows your device's default channel. Or a smaller mesh still running LongFast that periodically broadcasts something like "This area runs ShortFast, come join us!"
Ah, maybe that's the 100 node limit I was thinking of. I'm still relatively new to this myself.