Optimizing client switching between Access Points

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I have a 7372 and R600 is there a way to set this up so that devices pick the AP providing the strongest signal?

I originally set them up with the same SSID but then all devices seemed to pickup on the 7372 instead of the R600, so right now I have two separate SSIDs
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Jeff Goldstein

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Posted 3 years ago

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Daniel M

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You’ll need a controller to do this satisfactorily.
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John D, AlphaDog

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If you have a controller, you will be able to enable 802.11r/k fast transitions. In my experience, I've found a lot of mobile clients will roam more aggressively on a network that supports this roaming standard.

Even without such, you can try to use the "smart-roam" functionality. Basically it causes the AP to pretend to go out of range (e.g. ignore you and send you disassociation packets) hoping it will convince the client to roam. You can check the support documents on smart-roam (short story: Set a roam factor of 3 to 5 if you have decent network coverage, be on the lookout for unexpectedly dropped connections).

You should also try increasing the bss-minrate to 5.5 or so in order to encourage clients with a weak connection to roam instead of trying a lower data rate.

Also, since you are combining a 2x2:2 N (300mbit) with a 3x3:3 AC (1300mbit) AP, you probably also want the AC AP to broadcast a specific AC SSID... Almost no client roaming algorithm I've seen is smart enough to understand that, for example 50% signal strength on a 3x3:3 AC AP is worth more real world throughput than even 100% signal strength on a 2x2:2 N AP. That way, you can pin desktops/laptops known to be in reach of the AC AP to stay on it. I've had a ton of problems when I mixed N and AP AP's that my desktops would roam over to N AP's because they appeared slightly stronger.

At the end of the day, though, other than devices that support 802.11r/k, I have not found adding a controller to make a huge difference in roaming behavior.
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Jeff Goldstein

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Hi - in the zone director screens where to you go to turn this on

"If you have a controller, you will be able to enable 802.11r/k fast transitions."
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Jeff Goldstein

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thank you for your response. that is definitely helpful, so net is that I would need a zone director to help with this, and that different SSID's are best for the two APs given that one is n and the other is ac.

So now a question on zone director. Does the zone director 1000 provide all the functionality you mentioned or do I need to have the 1100?

Thank you
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Jeff Goldstein

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I should have asked if the zone director 1000 supports ac, like the R600 AP?
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Jeff Goldstein

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One more question - I noticed that Ruckus has released Xclaim...any thoughts on it for home use vs the setup I have?
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John D, AlphaDog

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So just to clarify: For mobile devices and other cases where you really don't care about the difference between AC and N, you can keep a universal SSID that has both AP's. I'd just recommend one specific AC one and then a universal one with all of the AP's.

You can set this up and the "smart-roam" functionality without a ZD; a ZD buys you 802.11k/v/r with ZoneFlex 9.8 and 9.9, which makes roaming a bit smoother.

At this point, the ZD 1000 is EOL'ed supporting FW 9.4 at the latest. It won't support the R600, and FW 9.4 is really old for the 7372 as well.

So like you, I'm a home user as well. I've got a ZD1100 + R700 + R600. I used to do a combo R700 and used ZF7982 network, but the annoyance of clients roaming from AC to N eventually drove me to set up an AC-only network. It's a pricey setup, but at the same time, being able to reliably serve my 120mbit internet connection to all my clients at full speed has made working from home a ton more productive.

For your last question about Xclaim: The Xclaim line hits a great price point, and gives you central management without the need for a controller, which is cost effective for us small-timers. But you still won't get 802.11k/r roaming support (you'll get the equivalent effect of running all your AP's standalone), whether or not that matters. Also, there won't be any BeamFlex -- the Xclaims use traditional omnidirectional antennas, not an adaptive beamforming antenna array like the ZoneFlex series. For me, I live in a crowded apartment complex where my last omnidirectional AC access point basically had a 6 foot effective range, and even if I am just slightly out of sight of the access point, speeds plummeted due to interference. ZoneFlex has been a miracle in being able to combat this interference. My old 2 AP setup was lucky to deliver 10-15mbits to the far corners of my apartment. Now my R600+R700 delivers 200mbit or more of AC throughput everywhere, as well as 50mbit even outdoors around my building!

My recommendation is that it's most cost effective to stick to your setup, and investigate setting up smart-roam and bss-minrate to see if you can encourage better roaming. And in the long run, consider replacing the 7372 with a R500 or R600 to homogenize.
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Jeff Goldstein

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I'm having no luck finding where to set smart-roam on the R600 or 7372...your guidance would be appreciated.

Thank you for your suggestions...Your suggestions are greatly appreciated and it sounds like my next purchase will be the R500 or another R600
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John D, AlphaDog

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Sure thing -- it's a command line only option. SSH into your AP's IP address and log in.

the relevant commands are :

roam_enable : get roam_enable
-- Get SmartRoam status
roam_enable : set roam_enable {enable|disable}
-- Enable/disable SmartRoam (facilitating roaming for sticky clients)
roam_factor : get roam_factor
-- Get Roam Factor (on 1-10 scale)
roam_factor : set roam_factor
-- Set Roam Factor (on 1-10 scale, lower means stickier)

So first, figure out the names of your wlans with " get wlanlist"

You will likely have at least wlan0 and wlan8 for dual-band one SSID, and probably wlan1 and wlan9 too if you made a separate SSID.

do "set roam_factor wlan0 3", "set roam_factor wlan8 3", and then "set roam_enable wlan0 enable", set "roam_enable wlan8 enable"

The roam factor can be tweaked as you desire. If set too high or with uncooperative clients, it may cause them to be disconnected abruptly while they are using wifi. I've found that 3 is roughly the highest that's tolerable, but it depends on what your clients do. I use my wifi to stream or Airplay mirror all the time, which requires hour(s) of uninterrupted wireless connectivity. If your clients do more casual work, nobody may even notice when the wifi drops out for 1-2 seconds while smart-roam forces the client to connect to a better AP.

Another item that helps with roaming is increasing the "bss-minrate". When a client gets really far from an AP, it may try talking to it at an extremely low data rate, which drags down the whole performance of your network. You can force your network to not support these low rates with "bss-minrate". By disallowing lower data rates, a client finding itself in this situation has no choice but to either disconnect from the AP or roam to a better one. This setting is independent from smart-roam but I've found it to have an additive effect for smaller roam_factors (1 and 2) and be gentler to clients by convincing them they need to roam without the need to abruptly disconnect them. Setting it is very similar: "set bss-minrate wlan0 5500", repeat for all wlans.

Oh yeah, another point of advice: Keep a list somewhere of all of these command-line tweaks you've made. The AP doesn't remember these for you, and there's no way to undo them other than issuing the opposite of every command you issued, or factory-resetting and starting over from scratch.
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Max O'Driscoll, AlphaDog

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...after reading this...thanks for info and I understand that
smart roam is configurable on APs using command line shell.

But is smart roam configurable from ZD gui (I have looked through but cannot find it on 9.9 or 9.8, am I blind)?

That would be useful! Any company types reading, how but putting that in a future f/w release.
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Jeff Goldstein

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Is there a secondary market for the ZD 1100? I'm assuming there must be for people/companies that have upgraded or moved to a different tech solution but can't find anything like this online
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John D, AlphaDog

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SmartRoam is not configurable from the GUI. It almost seems like certain advanced settings that require careful tuning with potential to mess up a network are not shown in the GUI.

As far as a secondary market, you can find them from time to time on eBay. However, at that point you are really on your own in terms of whether or not the hardware works, etc. This is definitely a tempting approach for home users like us, because otherwise it is difficult to justify the cost of a controller for a home deployment consisting of just an AP or two.
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John D, AlphaDog

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I think it's worth pointing out again that adding a controller is not a silver bullet for roaming troubles. The controller will only add 802.11r/k (and with 9.9, v) fast roaming extensions, but will not necessarily force clients to make better roaming decisions, and will only make a difference to clients that actually support these roaming standards (such as iOS 7.0+ devices)

The majority of roaming issues are solved with smart-roam or client-side settings (for Windows clients that allow you to choose roaming settings), and not making your network overly complicated (like mixing a 300mbit and 1300mbit device such that the best roaming decision is no longer a simple matter of choosing the strongest signal).

Since a ZD1100 is quite pricey for a home user, you probably don't want to get one then feel disappointed it didn't accomplish what you were trying to do. The money is much better spent switching out that 7372 for a R600, or adding another one if borderline 5GHz coverage is yet another reason why clients are making a poor vs poorer choice when roaming.
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Max O'Driscoll, AlphaDog

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Mildly off-topic:
Tee, hee..
John said
"SmartRoam is not configurable from the GUI. It almost seems like certain advanced settings that require careful tuning with potential to mess up a network are not shown in the GUI. "

As if there were not enough settings for me to pancake my wifi network with already. I don't think adding a smart roam item on AP or AP groups page would would tip me over the edge from clumsy idiot to malign destroyer of networks.

Always interesting to see what is simplified into a gui and what is hidden back in command line.

As suspected there is no ZD gui setting for smart roam config...pity as it strikes me as one of the things that would alleviate some issues with clients holding on to unsuitable APs.
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John D, AlphaDog

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I think it's more what functionality *has* to be wrapped into a GUI, and what stuff is not critical to network functionality is just available to tune at a command line by instruction of a support tech.

As I said, smart-roam does have its caveats, and I find on my network even level 3 is too high. It produces dead zones on my network where clients want to roam to a slightly out of range AP, which then proceeds to kick them off, and this cycle repeats every few minutes, resulting in a client that's unable to do streaming video or anything else that requires a continuous network connection.

It's useful for kicking off egregiously sticky clients, but quite honestly I have not seen one of those in ages, and the claims made about iOS being sticky, in my experience, have not been true for at least 2 major releases of iOS now.

Jeff wasn't very specific, but his issue dealt with clients picking a N AP over an AC AP. This is not something that SmartRoam can help you out with either if the client has a good reach to either AP.
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Michael Brado, Official Rep

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If sticky client manufacturers work out their radio driver/supplicant issues, our
smart-roam would not be necessary. Being a corner-case usage utility, the
command was designed to be configured by ZD in configure/WLAN mode, and
not exposed at the WebUI.
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Bram Ueffing

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@John Dong: thank you for the clear and detailed instructions, I'm going to experiment with this (using 2 7982's) to make users roam to the nearest AP in a high density setting (about 150 clients max within a single large room).

I have another, related, question: is it possible to stimulate clients to connect to a different AP when a preset number of clients are connected? In my case, I'd like to get clients to connect to the other AP when one of them has around 80 associations.

I know this will work with a ZD, but are there any options to do this standalone?
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Monnat Systems, AlphaDog

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Hi Bram,

You can use Max client feature which allows you at set a limit. Take a look at the screenshot for more info:

Configure --> WLAN --> Edit --> Advanced settings: Max clients

http://prntscr.com/5oob1y

once set limit is reached, that AP will stop accepting new connections for that WLAN

Hope this helps.
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Bram Ueffing

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Thanks, but I'd need to have a zone director for that though?
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John D, AlphaDog

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You don't need a ZD for setting absolute max # of clients. Per the ZF 9.8 CLI manual:

----
max-aid
Use max-aid to limit the number of clients that can associate to the WLAN.
Syntax
get max-aid
set max-aid [value]
Description
get max-aid -- Get the maximum number of allowed associated IDs for the WLAN
set max-aid [value] -- Set the maximum number of associated IDs allowed for the WLAN
Example
rkscli: get max-aid wlan0 Max Assoc ID is 256
OK
rkscli: set max-aid wlan0 100 OK
----

So you can set this per wlan (e.g. per band) on each AP. What the ZoneDirector gets you is dynamic load balancing, which basically sets soft and hard max client limits per AP dynamically based off whether or not there's a nearby alternative AP and how many clients are associated with each AP at the exact point in time a new client attempts to associate.

But if you know, for example, there's only going to be 30 clients in an area where two AP's cover, you can set the max-aid to 20 as a crude simulation of the ZoneDirector load balancing ability.
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Bram Ueffing

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Great, that's perfect! This is indeed the situation that I'm planning for.
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Jeff Goldstein

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Hi - in the zone director screens where to you go to turn this on

"If you have a controller, you will be able to enable 802.11r/k fast transitions."
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John D, AlphaDog

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It's under your wlan's settings (Config -> Wlan -> hit edit on your wlan). You'll find a checkbox for 802.11r (FT Roaming) and one for 802.11k neighbor lists — it's best to enable both or disable both.

Note that turning on 802.11r may cause ancient clients (e.g. more than 3 year old OS'es) to refuse to connect to your network. If you have to support such clients, you may need to clone your wlan so that you have one that's 802.11k/r capable and one that is not.
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John D, AlphaDog

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EDIT, now that I have access to my ZD, I can be more explicit. Just go to Config -> Wlan, hit Edit by your wlan, and then check the two red boxed items:



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Jeff Goldstein

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that's great - thank you