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Comment by grk | Hacker News Reader

Does roaming devices between APs actually work? I reading through ubiquiti forums and it looks like they used to support it, but backed out of it.

My specific usecase is moving around the office while being on google hangouts on my phone.

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Not the OP, but yes it works great. The APs themselves do not need to support it, the client does. But you can also do zero handoff (quicker, like for voip heavy environments) and that needs AP support. Read https://help.ubnt.com/hc/en-us/articles/205144590-UniFi-What...

It's worth noting that newer Ubiquity APs no longer support Zero Handoff. Part of the problem was that all the APs needed to be on the same channel, which caused co-channel interference under heavy usage; there was a significant performance impact. (Also, I believe that chipset in the newer Unifi models just don't support it.)

Without it, clients can still roam between APs, but you'll notice ~1 second of packet drops each time your client roams to a new AP. It won't drop a VoIP call, but you'll notice a moment of silence when it happens.

The future is 802.11r/k/v, which will allow clients to roam themselves quickly between participating BSSIDs without needing to renegotiate the connection each time (as opposed to relying on pure AP-based hacks).

It really depends on the phone and the AP.

https://support.apple.com/en-us/HT202628

I thought you could use aggressive approaches by letting the AP's just kick the device off the AP so it's forced to join a better one?

In theory that works, but a lot of phones get angry when the AP stops talking to it. It just assumes that you lost WiFi and disconnects and doesn't try to rejoin right away

Thanks, that link is very informative.

Yes it absolutely does, but it is dependent on the station (the client) doing so. One of my gripes about Wi-Fi is that it delegates too much to the station - your experience is thus dictated by whoever wrote your phone/computer's Wi-Fi chipset driver, and how they interpret the standard.

Any Wi-Fi network supports roaming on the network side, you just need all of your access points to use the same SSID, and to dump users onto the same subnet consistently (otherwise you'll need to re-IP after roaming).

Should I set channels on the APs in some specific way?

We're using mostly apple hardware + ubiquiti APs, and to be honest I expected everything to "just work" with the defaults...

Channel selection won't affect roaming, so you shouldn't need to. What specific problem are you having?

I've heard that Apple hardware in particular sticks with an AP longer than other devices, the Apple device is not continually looking for the best connection, it sticks with what it started with until the signal gets very weak. Don't take this literally but it's like Apple waits until you're down to one bar while some others wait until you're down to two bars before looking for a stronger connection from another AP.

You should make sure the APs don't interfere with each other. The automatic channel selection didn't work well for me. I had to manually set my two APs at each end of the 2.4GHz spectrum. It's also a good idea to turn on wide band channel. If you have an Android device somewhere you can download wifi analyser to make sure the channels don't overlap.

If you option-click on the wifi symbol in the macOS menu bar, there's an option to access various diagnostic tools. One of them gives you channel recommendations as well.

I have a ubiquiti AP and as part of the set up it did a scan which picked my channels based on what it scanned and it seemed to do a decent job. You can go into the controller software to initiate a scan, though it will kick everything off the network for a few minutes.

They don't need to be on different channels, but it's recommended for performance (due to co-channel interference).

Think of it this way: Each channel provides a fixed amount of bandwidth, and neighboring APs need to overlap slightly to provide seamless coverage. As a first order approximation, if two APs are on the same channel you'll have twice the range, but half the bandwidth because the spectrum would be shared between them.

(It's actually slightly worse than this, because collisions will happen causing additional overhead.)

So on that note, do you have any brands/manufacturers/chipsets that you see as particularly good in terms of being a client?

Its always a gamble when I get a new phone/laptop/device if it will work with the multi-AP setup I have in my house, and I'm really tired of getting something and bringing it home only to find it hangs on to the furthest AP for dear life.

Ubiquiti UniFi AC or UniFi AC-LR. I'm not the poster above you were asking. Never need rebooting. Present a single AP name for multiple devices and both 2.4 and 5.x GHz. Reasonable price for home use. Based on personal experience in a large house. grk, roaming works just fine.

Klathmon was asking about clients, not APs.

> So on that note, do you have any brands/manufacturers/chipsets that you see as particularly good in terms of being a client?

As a client, the Intel wifi hardware works quite well, as does the software stack on top of it (at least on Linux). It helps that they're the ones who've written a fair bit of the wifi stack itself.

I believe it is the responsibility of the client to correctly roam between similarly named APs. I vaguely recall reading into this when I read that my unifi AP didn't support roaming. I could be mistaken though!

It work but on every border there will be a zone where you can join AP on either side. You can be still on weak AP but device will consider it weak enough and won't switch just yet.

In the end if you have a problem with WiFi (e.g. not a default transparent walls and no interference) you will have a problem with it forever.

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