How many mesh hops?

I thought I’d separate out this question from my previous.

How many mesh hops can Alta handle. I fully understand you get about >50% loss in throughput per hop, however I an outdoor network I’m looking to build with mmwave backhauls out past the comfort point. I’ve had heavy fog or big snowflakes take those links down and I want to maintain basic connectivity.

Are there any artificial limitations imposed by Alta on hop count or is it just based on when you’ve halved throughput too many times to be useful.


I think you’re not giving mmWave its fair shot here- depending on your hardware you can go well over 1km without it ever disconnecting due to rainfall.

Isaac, I have over 1500 mmwave radios in the field from 5 vendors. I could not be giving it a fairer shot.

Makes sense! I just would be surprised to see a low gain WiFi AP mesh pass traffic of any significance at distances beyond mmWave reliability.

“of any significance” is subjective and really 10Mbps would be just fine. I only anticipate maybe 3-4 hours a year in this state. It’s only really heavy fog or giant snowflokes that take down the 60Ghz. Heavy/wet snow or rain has been fine, the fog and huge flakes just mince the signal too much I guess.

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@danden There are no self-imposed limits on the number of hops in an Alta mesh. Of course, it’s always a good idea to limit them to an absolutely minimum wherever possible.

That’s Jeff. Is this just using RTSP for loop avoidance?

We don’t currently use RSTP over WiFi, but our own proprietary protocol for loop avoidance. We do plan to add RSTP priority at some point, though.

ok, is this proprietary solution in the switches as well? ie, if I run a ring of AP6 outdoor units with 2 of them plugged directly into an Alta switch I’ll get the loop avoidance?

What’s expected failover/adaptation time? Say a mesh hop goes down, how quickly will traffic ‘turn around’ and go the other way?

also, if I use something like tachyon mmwave PTP radios to get data back to the main switch through fewer hops, will your protocol traverse that bridged layer2 hop?

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@danden No, the switches run standard RSTP/MSTP/STP with pretty standard default timeouts.

You should get loop avoidance with a ring though I haven’t tested that specifically myself. Hops with a higher hop-count will get penalized as the mesh forms.

It may take some time for the mesh to reconfigure, depending on the number of hops that need to reconnect. I would guess ~10-15 seconds per hop, but I have not tried this specifically. We use standard STA<>AP association, i.e. not 802.11s, so each node needs to create an individual connection to its uplink.

Yes, you should be able to use any L2 connection as an uplink to the “main network.” We don’t really filter anything other than STP frames.