Please help me understand zero handoff

S

S-F

Gawd
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Aug 5, 2010
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I recently updated my Unifi AP's to 3.X firmware. I have noticed that roaming between AP's has gotten fantastic! I simply don't understand how this works. When I look at the Unifi controller it still says the AP's are on different channels. I thought that zero handoff meant that they operate on the same channel? What's happening when I move between AP's?
 
I have mine setup for ZH. All APs should be listed on the same channel. You may need to re-provision the WLAN group for it to take effect. Also you can try to force it by changing the AP radio setting. For some reason mine had different power levels (auto vs low, med, etc.) I set all of mine to low so I don't have too much bleed out of my house.

Ripped from here

Zero-Handoff Roaming

One of the challenges of multi-AP wireless networks is not all clients can seamlessly transition from a weak signal from one AP to a stronger signal from a closer AP. Sensitive devices, such as VoIP phones, could suffer performance problems such as call dropping while moving from one AP zone to another.

With UniFi's "Zero-Handoff" (ZH) roaming, multiple APs appear as a single virtual AP to the wireless client, thus the client doesn't have to switch APs as it roams. The UniFi system determines the optimal AP to provide the connection to the client. They can do this without the UniFi controller connected.

Utilizing this feature requires creating a WLAN group with ZH enabled (shown below), then creating one or more WLANs in that group and applying that group to multiple APs.

Note, not all of the UniFi APs appear to support ZH. I noticed the UniFi AP-Pro, AP-LR and AP-Outdoor allowed me to add them to a WLAN group with Zero-Handoff enabled, but the UniFi AP-AC did not.

Zero Handoff
Zero Handoff

When multiple APs are broadcasting the same SSID as they do in normal operation, each AP will show up in a wireless network utility, such as the recently reviewed Metageek inSSIDer, with a unique MAC address. Using inSSIDer, I noticed that once I enabled ZH on multiple UniFi APs, I saw only one MAC address for the ZH configured SSIDs instead of two MAC addresses. This meant my PC saw only a single AP and thus would not have to switch APs as I moved from one AP zone to the other.

I ran a simple test by running a continuous ping from a wireless laptop while connected and standing close to one AP configured in a ZH SSID. I then walked my laptop next to a second AP in the same ZH group. The pings continued uninterrupted, meaning I hadn't lost a connection. Yet, via the UniFi controller AP overview screen, I could see my connection changed from one physical AP to the other. Neat!
Click to expand...

and this
 
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Hmmmmm. I just have the default site set up. I simply added some Unifi AP's to my network, which only had a Loco M2 and the built in radio on my router. I have since turned the router radio off and only use the Unifi AP's for WiFi in the house. So I hadn't configured a new WLAN Group. But I did notice that once I switched to the 3.x controller / firmware that my devices now roam where before they wouldn't unless I cycled power to the radio on the device. It's working stupendously! I'll make a backup and try to create a new WLAN with ZH enabled..... Tomorrow, when the Mrs. isn't watching a soap opera on her lap top.
 
TBH roaming works fine without ZH on the UAPs. For home I would leave it off.
 
Yes, well. It absolutely sucked before the upgrade to 3.x. Like I said previously, I would have to power cycle the WiFi radio on every device I have to roam from inside to outside. I didn't do anything except change to 3.x and now it works swimmingly.

I dunno
 
S-F said:
Yes, well. It absolutely sucked before the upgrade to 3.x. Like I said previously, I would have to power cycle the WiFi radio on every device I have to roam from inside to outside. I didn't do anything except change to 3.x and now it works swimmingly.

I dunno
Click to expand...

Good to hear! However if you have anything latency sensitive or use VOIP you may want to try ZH.
 
this is great to hear. The 3.x version that was public last week, has many issues. If you sign up for the beta 3.x software you can download 3.1.18 which was the latest as of last week.

3.1.18 is close to the end of the beta and ZH now works for the 802.11ac model as well.
 
I've been using 3.1.9 since I made the switch a while ago and I have only seen improvements. Granted I'm only using 2 AP'S and no more than a dozen or so devices. And the improvements are only for roaming.

@ /usr/home,
Is there any specific reason you suggest not using ZH? Can it negatively effect performance in some way?
 
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S-F said:
I've been using 3.1.9 since I made the switch a while ago and I have only seen improvements. Granted I'm only using 2 AP'S and no more than a dozen or so devices. And the improvements are only for roaming.

@ /usr/home,
Is there any specific reason you suggest not using ZH? Can it negatively effect performance in some way?
Click to expand...

Just reports of it being buggy and "roaming" works just fine without ZH. The only time ZH might be helpful is when using VOIP while moving between APs.
 
I use ZH and quite like it. However I can't set the power on my UAP's on my own when in a ZH group, so maybe I need to upgrade the software version...
 
I used ZH for a client with 11 AP's. When it worked it was good, but it's just not bulletproof yet, it would lock up on occasion or have SSID's disappear. I kept them on 3.x but ditched ZH and went with just regular roaming/different channels and it's much more reliable now.
 
Most people on Unifi forums say ZHO isn't worth it. The AP's have to be on the same channel and have to be an EXACT distance apart with very little overlap, but yet not too far.
 
pretty much the only time you NEED ZHO is if you're doing like voip calls while moving... very specific use case...

also, wireless (not DECT, like actual wifi) ip phones suck, it's why none of the big guys make them and they're not very popular
 
goodcooper said:
pretty much the only time you NEED ZHO is if you're doing like voip calls while moving... very specific use case...

also, wireless (not DECT, like actual wifi) ip phones suck, it's why none of the big guys make them and they're not very popular
Click to expand...

Cisco not a big player then?

Used multiple 7921Gs in a previous job and never had a problem with them. Definitely roamed without a problem, and never dropped a call. Not sure what wireless infrastructure supported them in that case, but the phones themselves were great.
 
NickTheSloth said:
Cisco not a big player then?

Used multiple 7921Gs in a previous job and never had a problem with them. Definitely roamed without a problem, and never dropped a call. Not sure what wireless infrastructure supported them in that case, but the phones themselves were great.
Click to expand...

you may be the minority then... everything i've heard about those say avoid like the plague...

i've got ~20 DECT ip phones out and they work flawlessly... for half the price (probably a 1/3 or 1/4 actually)
 
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