jcremin
join:2009-12-22
Siren, WI
kudos:2 | UBNT Disconnect IssueI have never been a fan of UBNT as an AP because they are so dammed difficult to troubleshoot compared to Mikrotik. However, I do have one AP that I've been having issues with a few clients randomly disconnecting from for not apparent reason. I turned on the client log file and found the following when it just happened a few minutes ago. Can anyone translate for me what might cause the below issue?
Nov 19 16:36:31 wpa-supplicant: CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys
Nov 19 16:36:31 wireless: ath0 New Access Point/Cell address:Not-Associated
Nov 19 16:36:31 wireless: ath0 New Access Point/Cell address:00:27:22:2A:EA:A3
Nov 19 16:36:31 wpa-supplicant: Associated with 00:27:22:2a:ea:a3
Nov 19 16:36:31 wpa-supplicant: WPA: Key negotiation completed with 00:27:22:2a:ea:a3 [PTK=CCMP GTK=CCMP]
Nov 19 16:36:31 wpa-supplicant: CTRL-EVENT-CONNECTED - Connection to 00:27:22:2a:ea:a3 completed (reauth) [id=0 id_str=]
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 CMack
join:2004-07-30
canada | can you post the connected client list? |
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Also what firmware are you on? They had a nasty re-keying issue with 5.2.1. |
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jcremin
join:2009-12-22
Siren, WI
kudos:2 | reply to jcremin
said by Newbie:Also what firmware are you on? They had a nasty re-keying issue with 5.2.1.
said by CMack:can you post the connected client list?
See attached screenshot. That should answer both questions.
The only potential issue I have is the noise floor. However, I have tried every channel, one by one, and while many of them have much better noise floors, the signals and/or performance is MUCH worse. I've been unhappy with this AP since the day I installed the RocketM2. I wonder if I should just rip it down and put a RB411AH back up there and try one of the MIMO 802.11n cards to see if that works better.
The only thing I really have to compare it with was a RB411AH with an XR2 running in 802.11b mode, which almost never dropped a single ping, but I wanted more than the 5mbps that it could supply. Right now with the Rocket M2 in a 10 mhz channel and with the few clients that are on this antenna, I'm getting about 10 megs on average. Once in a while it might peak at 14 or 15 megs, but that's pretty rare. |
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Looks like it just disconnected from noise, the SNR isn't enough to have a reliable link, -77 noisefloor only gives 27db on a -50 link, I believe the RM2 has to have 30db for the highest speed. -50 is also a bit loud for a link but shouldn't be a problem as long as it doesn't get louder. Have you been able to identify where the noise is coming from? What antenna are you using with the RM2? What does the airview show for frequency usage? You might be able to find a cleaner piece of frequency by using an offset. With a link RX at 3.25mbps it is eating up a lot of airtime vs a 65. |
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Saw those same entries in a log file with a P2P link that kept disconnecting. Drove me crazy until I tried WEP instead of WPA. Problem went away, not sure why. |
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I dont believe i've seen a noisefloor like that with 10mhz CW... That is pretty tough.
The only thing I can think of that could improve the situation is possibly a shield kit if you do not have one. |
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said by jim_p_price7:Saw those same entries in a log file with a P2P link that kept disconnecting. Drove me crazy until I tried WEP instead of WPA. Problem went away, not sure why.
Bingo.
I have seen this same issue in noisy situations.
For me, with WEP, everything was fine. With WPA2, I had random disconnects.
(once a day).
In my case, I had traffic shaping turned on the client.
When I turned it off, it solved the problem. Here is a thread on it:
»forum.ubnt.com/showthread.php?t=63545
So I think what happens is that with WPA and WPA2, there are timeouts
during the connection process. If a response isn't received in X milliseconds,
then the client disconnects.
With a high noise situation, these timeouts may happen with higher probabilty
(since there are more re-transmits happening). Likewise when you turn on
traffic shapping (since it slows down sending of packets).
At least that is my theory. I could be wrong, it wouldn't be the first time. 
I consider this a bug. Not sure what Ubiquiti thinks.
John |
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 InssomniakThe GlitchPremium
join:2005-04-06
Cayuga, ON
kudos:1 | reply to jcremin
Im gonna guess its noise, you are seeing its effects more, because you moved from the very robust 11b modulations to g/n modulations. Have you tried enabling airmax? Used channel shifting? I had one 10mhz AP that didnt work on any standard channel well, I shifted it down to 2464mhz and its perfect now.
If you go back to mikrotik, the 2 chain .11n stuff works well with ubiquiti, use 5.5.2, get rid off all the B rates, even the 6,9, rates in G mode go too. If your clients are all N clients, just enable N mode! Even better.
I found in noisy environments using channel shifting on mikrotik works well to slip in between noise just like you can with the RocketM
It took me a while, but I took a Mikrotik AP 411AH with a MIMO N card and 39 customers in terrible shape with mixed G/N clients and managed to get it working very well in the right channel/firmware/settings (RTS). Got calls from customers saying their voip has never worked better!
Sometimes you just have to spend a few hours with an AP
--
OptionsDSL Wireless Internet
»www.optionsdsl.ca |
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Is there a reason why you aren't using Airmax? |
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Reviews:
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said by johnk:said by jim_p_price7:Saw those same entries in a log file with a P2P link that kept disconnecting. Drove me crazy until I tried WEP instead of WPA. Problem went away, not sure why.
Bingo. I have seen this same issue in noisy situations. For me, with WEP, everything was fine. With WPA2, I had random disconnects. (once a day). In my case, I had traffic shaping turned on the client. When I turned it off, it solved the problem. Here is a thread on it: » forum.ubnt.com/showthread.php?t=63545So I think what happens is that with WPA and WPA2, there are timeouts during the connection process. If a response isn't received in X milliseconds, then the client disconnects. With a high noise situation, these timeouts may happen with higher probabilty (since there are more re-transmits happening). Likewise when you turn on traffic shapping (since it slows down sending of packets). At least that is my theory. I could be wrong, it wouldn't be the first time. I consider this a bug. Not sure what Ubiquiti thinks. John Correct - I too had traffic shaping on the affected link. |
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jcremin
join:2009-12-22
Siren, WI
kudos:2 | reply to scobywhru
said by scobywhru:Looks like it just disconnected from noise, the SNR isn't enough to have a reliable link, -77 noisefloor only gives 27db on a -50 link, I believe the RM2 has to have 30db for the highest speed. -50 is also a bit loud for a link but shouldn't be a problem as long as it doesn't get louder. Have you been able to identify where the noise is coming from? What antenna are you using with the RM2? What does the airview show for frequency usage? You might be able to find a cleaner piece of frequency by using an offset. With a link RX at 3.25mbps it is eating up a lot of airtime vs a 65. Most of my clients on almost all of my Mikrotik AP's have FAR less than 27db SNR, and none of them seem to have this problem other than some that are -80's signal, which is to be expected. It doesn't make sense to me why this tower (which has about the best overall signals of any AP on my network) would act up but not the ones that have twice as many clients, many with signals in the -70's and -80's.
I haven't yet tried doing an offset, partially because my own office runs on the connection and it is tough to mess with it during the day, when we've got VoIP phones and such, and partially because every change seems to take an eternity compared to doing it on an MT system.
If it is truly noise, I can't tell where it is coming from. The noise floor never changes more than a dB, and neither side seems to change at all whenever I have the disconnect issue. The part that seems most suspicious to me is the fact that when I change frequencies, signals get worse as noise floors get better. Makes me think that there's something wrong with the Rocket or the antenna. It's the same kind of thing I see on a 900mhz with a bandpass filter. Obviously the frequencies outside of the filter range have bad signals because the filter is doing it's job, but the noise floors are also better for the same reason. |
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jcremin
join:2009-12-22
Siren, WI
kudos:2 | reply to Newbie
said by jim_p_price7:Saw those same entries in a log file with a P2P link that kept disconnecting. Drove me crazy until I tried WEP instead of WPA. Problem went away, not sure why.
Strange. Not sure why that would affect it.
said by Newbie:I dont believe i've seen a noisefloor like that with 10mhz CW... That is pretty tough. Same here. It's the only 2.4 AP on my entire network that has a noise floor reading that bad, and is WAY worse than the Mikrotik I had in place beforehand. And I'm not in a big city. I'm in a small village with a population of around 900 people. I have AP's that can see a LOT more and don't have nearly the troubles this one does. |
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jcremin
join:2009-12-22
Siren, WI
kudos:2 | reply to jim_p_price7
said by jim_p_price7:I too had traffic shaping on the affected link. The only traffic shaping I'm using is simple queues on a PPPoE concentrator, so nothing on the AP or CPE. |
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jcremin
join:2009-12-22
Siren, WI
kudos:2 | reply to wirelessdog
said by Inssomniak:Im gonna guess its noise, you are seeing its effects more, because you moved from the very robust 11b modulations to g/n modulations. Have you tried enabling airmax? Used channel shifting? I had one 10mhz AP that didnt work on any standard channel well, I shifted it down to 2464mhz and its perfect now.
If you go back to mikrotik, the 2 chain .11n stuff works well with ubiquiti, use 5.5.2, get rid off all the B rates, even the 6,9, rates in G mode go too. If your clients are all N clients, just enable N mode! Even better.
I found in noisy environments using channel shifting on mikrotik works well to slip in between noise just like you can with the RocketM
It took me a while, but I took a Mikrotik AP 411AH with a MIMO N card and 39 customers in terrible shape with mixed G/N clients and managed to get it working very well in the right channel/firmware/settings (RTS). Got calls from customers saying their voip has never worked better!
Sometimes you just have to spend a few hours with an AP Yeah, the "robustness" is the reason I used to use B-mode across my whole network. Since swapping this AP out for the Rocket, I have also migrated all the rest of my 2.4ghz AP's to a 10mhz 11g channels. I haven't seen the same thing on any of the rest of them, so unless there's a big difference between 11g and 11n where n is yet another step towards being susceptible to interference.
I'm pretty seriously considering swapping it back out to Mikrotik. I've never liked UBNT as an AP and I figured I would give it a try. Nothing but headaches to try to troubleshoot things. I'll spend a bit more time experimenting with this AP to exhaust all my options, but I'm assuming that in the end, I'll probably end up back with MT as the AP.
said by wirelessdog:Is there a reason why you aren't using Airmax? I did have it enabled awhile ago. Shut it off to see if it made a difference. Same speed, same latency, same disconnects. Didn't seem to help or hurt me much in this situation. |
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@Jcremin - Just for kicks, try a switch to WEP. I can't explain it, but that worked miracles for me and I don't know why. |
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jcremin
join:2009-12-22
Siren, WI
kudos:2 | said by jim_p_price7:@Jcremin - Just for kicks, try a switch to WEP. I can't explain it, but that worked miracles for me and I don't know why. If I get a chance, I'll give it a shot tomorrow and report back. Except for my office, the rest of the accounts are residential and I'm at the time of day they are most likely to start hopping online, so I don't want to disrupt things right now.
And this issue isn't super urgent. It has been happening for awhile now and I tinker with it here and there. It does affect our office, though, and I hate getting a dropped call when the VoIP cuts out for a few seconds. |
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Are you using all M series clients? |
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jcremin
join:2009-12-22
Siren, WI
kudos:2 | said by wirelessdog:Are you using all M series clients?
Yes, every single client is either an NSM2 or an NB2. |
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RTS on or off? |
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