Upload/Download (Speedflex) test cause other clients to drop packets

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I have a hotel with mostly r600's and I've been getting reports of dropping connections. In my tests the signal doesn't actually drop, but when one client starts a transfer such as an internet internet speed test or if I do a Speedflex test on the management vlan, I see a very noticeable degradation of another client at least on the same AP. Running a ping just on a client to the firewall inside interface (Different or same vlan), the response times will start climbing and eventually start timing out until the speedflex test finishes on the other client. This is causing all sorts of issues since everyone seems to run a speed test when they have a slowdown and then its downhill from there as every speed test makes it worse until they all give up. Is there anything in particular I should look into to identify what might be causing this? Thanks
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Josh Safranek

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Posted 1 year ago

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Robert Lowe

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Hi Josh, a couple of initial questions:

Do you experience the issue on both the 2.4GHz radio and the 5GHz radio? 
If you replicate the issue and test with client on 2.4GHz does it cause 5GHz clients to drop?
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Michael Brado, Official Rep

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Did you have help planning the AP locations and do a site survey?

Hotels with multiple long retangular floors should locate APs every 2-4 rooms on alternate sides of the hallway,
and alternate the pattern on the floor(s) above/below, for best 3 dimensional RF coverage.

Too many hotels/dorms put APs in hallways, in the same place on floors above/below, making it very difficult
for clients to determine the best AP to communicate through (and may stick on first one).

You should collect an AP support info from the AP that you are testing Speedflex to multiple clients on, to be sure
the clients have good wireless connections (PER < 10%, RSSI - PER >= 25).

Otherwise, network design is the next question.  Are the APs and controller on a separate management VLAN
and all your WLAN traffic switched onto different client VLANs?  Too much broadcast or multicast on networks
can sometimes lead to periods of degraded throughput.
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Josh Safranek

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Thanks for the follow up guys,
Robert, It appears it only happens on the same radio frequency. My two systems I was using were both on 2.4GHz and don't see the issue when I get one to connect to 5GHz or if I have them both on 5Ghz but to get them both on 5GHz, I have to relocate out of the guest room for it to connect at 5GHz which leads me to Michael's questions.
Yes we had a site survey done prior to the Ruckus install and I am now finding that we didn't install as many APs as we probably should have because of another hotel we had with the same R600's and similar placement. We have actually been running for over a year on this newer install and just recently have been informed of the issue but they said this connectivity issue just started a few months ago. From what I'm seeing now, I believe the issue has been ongoing from the beginning. 
I believe the main issue here versus our previous hotel is the building material. The previous was cinder block construction between the hallway (AP's are all 2nd floor hallway of two story hotels) and this newer install is the more dense bricks like you see on the exterior of houses. If I run a speedflex on my phone from even the lower hallway, I can get 500-700Mb between me and the AP, but as soon as I walk through the room door, it plummets to around 10Mb. 
I'm not onsite anymore so I can't easily get AP support info to my client but I'm pretty sure the signal levels are not sufficient especially when client devices are attempting to upload data. The last thing I did before I left today was to put a mesh'd R900 in the 1st floor hallway ceiling (Don't have cabling, but do have power) close to my room and made sure I was connecting through it. It seemed to resolve all my issues. It's left me in a difficult situation because I know I should have another site survey done, but funds are already tight and I'd probably need to choose a site survey or more APs to mesh in the lower hallway ceiling. From what I experienced today with adding that one, I'm pretty sure it will help, but am also told I need to worry about adding too many.
As for the network design, The APs are on a separate management vlan from the guests, all new cabling under the distance limitations, connected gigabit to Juniper EX3300's. I do have a device that I still need to install for the dynamic vlans of clients. I will now be putting the rush on installing it and should correct any broadcast/multicast issues which I also think may be contributing to the degradation. 
If I need to go with using mesh'd R600's on the first floor, am I opening myself up to other issues aside from potentially having too many APs and getting interference from each other? I'm not too concerned about bandwidth reduction between a mesh'd AP at this point. I just need to get something to help the issues as they are at the beginning of the busy season. I understand there are many aspects to the design phase which were overlooked and skimped on with this install. I'm most concerned that I will open up other problems by using mesh'd APs and will have to go back again to the owners for more money for a full survey, which will undoubtedly recommend cabling, switches and placing them in a staggered layout as you suggested.

Thanks! 
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Robert Lowe

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Firstly to the 'issue' you are experiencing; as it only happens on 2.4GHz I would be fairly confident in saying I think you are experiencing an airtime utilisation issue.
This would most likely be a combination of co-channel interference (or adjacent channel interference) on the band mostly due to the fact you have AP's installed in corridors. This will mean airtime utilisation on the channel is already higher than nescassary. Also the fact that you report low signal strength in the bedroom means it's more likely that you will be using lower modulation techniques, which take up more airtime, and also are more likely to get retransmission so which again adds to airtime utilisation. If the utilisation gets exhausted clients can't transmit so it give the appearance of no network.

First questions, are you using channelfly or background scanning for channel selection? What channels are selected in the AP group for the AP's? If you go into the controller (assuming a ZD) and under the monitor tab choose an AP, how many neighbor APs does it report and on what channels? If you are not familiar with the ZD it's in the bottom right of the monitor AP screen.

There's lots more I'm afraid but I'll leave it there for now so to not overload you.

PS: more APs mesh or not should be a last resort. I would say time and money better spent trying to find optimal location and configuration for what you have already.
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Josh Safranek

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Robert, Yes we have background scanning enabled. All the channels are selected. It looks like Channelfly is enabled also.  Pretty much every radio setting is the default since this is the way it was originally installed for us and was working at all our other locations. At this hotel, we have one R600 roughly every 60' on second floor.  This AP monitoring info below was the one I primarily connected to before I put in the mesh AP (Inn AP #12 MESH).  I appreciate your input.

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Robert Lowe

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Hi Josh, OK so neighbour list may need sorting by channel to see all 2.4 but the utilisation stats aren't as high as I would have expected if you had s airtime issue. Although you do have a decent number if phy errors but the drop/retry rate is low.

Hate to say it but I think the best way to progress is for another site survey to be completed. I would suggest the following:

Full passive heat map with professional software.
As your issue is with 2.4GHz then I also recommend a spectrum analysis survey be completed. If you find a VAR who uses Ekahau Pro the two can now be combined into a single survey.
Physical survey of possible alternative locations for the APs. You really need to consider getting them out of the corridor. Along with some AP on a stick surveys of these locations to verify they will give you the coverage you need.

I work specifically with hotels and MDUs in the UK and I can safely say that corridor deployments are always the ones which have issues. You need to get the APs as close to the users as possible.
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Robert Lowe

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Sorry couple of basic questions I forgot to ask:

How are the APs mounted? Wall or Ceiling
How many floors does the hotel have?
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Josh Safranek

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Hotel is only 2 floors and APs are mounted above the 2nd floors false ceiling along center of hallway pointing down.
Thank you! 
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Karl Lavender

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I agree with Robert, the first thing I would suggest in a hotel type environment where you have limited control over the devices introduced, is to disable Channelfly, allow background scanning to manage the channels, only use channels 1,6,11, probably set the background scan time out to 2 minutes or so - it'll probably default to 20 sec which will cause a lot of channel changes in a hotel due to the introduced interference.

If you can get remote access to the controller CLI, set the WLANs to OFDM only.

Considering you are running R600 etc, you should be able to check the 802.11r and 802.11k which will probably help movement and allow you to potentially get better client information from the controller if their device is 802.11k compliant.

I have no idea how the site was deployed and what your surveys look like, but if your 2.4 is covering everything so well with that much overlap, you may be able to drop it down by just 2 or 3dB and test again for coverage - you may find the coverage is still good and there is less overlap on the 2.4, giving you cleaner air and probably higher throughput.
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Josh Safranek

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Thanks for all the input and help. I will try some of the changes you've both recommended and try to arrange for a full site survey with spectrum analysis. 
Robert, do you have any tips on how to accomplish a thorough site survey when there is limited access to rooms because of occupancy? 

Josh
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Robert Lowe

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The only advice o can offer really is what I do in this situation:

Be open and honest with the hotel management, tell them that if they want the issues with the WiFi to get resolved then you require access to as many rooms as possible during your window. Tell them that if you access 40% of rooms then you can only be 40% confident that any changes you reccomend post survey will work.

Ask to be accompanied by a member of hotel staff to allow you access to occupied (as in checked in but out of the room) guests.

Perform as much of the data gathering as possible during the check out/in window and keep in contact with the reception team to get updates on checked out guests.

If you can't access a specific room or rooms try and get the rooms either side so the software can interpellate the signal.

For the sampling of alternate locations, ask the hotel for a block of 6-8 rooms directly above and below each other and a window to do your testing. Mount your AP in the alternate location and walk all rooms to gather as much data about signal propagation as possible. If the hotel as I uniform shape then you can simulate the other areas with software.