5Ghz P2P problem - disconnections when signal is good

RouterOS Wireless Networking
1

I’ve got a pretty strange issue here with a point to point link. Total link distance is about 20km, with good Fresnel (about a 0.8F1 if I recall what RMD said).

On the A end I’ve got an RB532 with an SR5 and XR5. The XR5 is this link, the SR5 is another point-to-point link that is working fine. The unit is powered by a 48v 500mA PS with appx 75ft cat5 cable. Antenna cable is RG8/U about 6ft long, antenna is Pac wireless GD58-29

On the Z end I’ve got an RB133 with XR5 for this link, R52H in 2.4Ghz-B mode for p2mp, and an R52 running another 5.3Ghz point to point link which is operating fine. Power supply is 18v 900mA. Antenna cable is RG8/U about 12ft, antenna is pac wireless GD5W-28.

When first configured signal strength on this link was -68 with a noise floor of -104, and it worked fine for about three days. Original configuration was for 5Ghz standard channel size, frequency 5785Mhz, nstream off, WPA/2 enabled.

After about three days, the link started flapping, and has kept doing so for about a week. I’ve tried every channel (even those with other equipment on them) including the “low band” 5.1-5.3Ghz and moving to 10Mhz channel spacing. I’ve also tried enabling nstream (wouldn’t stay associated for more than 4-5 seconds), and disabling WPA (no effect).

In all cases that it would even associate for 5.1-5.3Ghz band signal was about -78 (out of tune for one end), on all hi-band (5.7GHz+) channels that would associate signal is -70 to -75 with SNR between 20 and 30dB. CCQ didn’t strike me as good, but when it’s up I can do 8Mbps TCP bi-directional through the link (aggregate). On 10Mhz channels, I had much more difficulty getting an association. Very few channels work, and it won’t stay up for even a few seconds.

Despite all of that, the link keeps flapping even though the signal is perfectly workable (several other links with the same A location have less signal and have been working flawlessly for months to years).

Any thoughts or suggestions? I’m not sure what’s wrong with this situation. The SNR is great (20-30dB), when the link is up signal is excellent and throughput is quite acceptable. Generally it will stay up through daylight hours, then flap at night - though as I write this the link is down at 12:30pm CST.

Wireless link going down
2

I can’t offer any suggestions but I’ll add I have a new link with RB411s and XR5s p2p and I have similar issues. Works about -55-60 perfectly 30mb throughput and after a day or so craps out disassociates. I play with it comes back for a good while and goes downhill again.

Not sure this has any relation to what you have but on my side I suspect bad antenna and will be swapping all of it out tomorrow. Only one side I keep having trouble with.

I have other links with same gear that works better than I ever expected. 4 miles with same gear as above and 5ghz turbo I see up to 58MB throughput and rock stable. Woohoo

Scott

3

We messed with it again today, with one of my techs on the far end so we could try lots of different settings. We went through a lot of different iterations, and finally landed on a 20Mhz channel, nstream enabled, polling enabled, framer disabled, CSMA disabled and switched the AP / client relationship around from one end to the other. Signal wasn’t any better, but with CSMA disabled the CCQ went up to 98-100% and throughput was good (~8Mbps aggregate)

Unfortunately, about 5 hours later, it started flapping like a bird with a broken wing again.

This time, I’m looking at it from the client side, so there’s not much I can try to change. However, I can say that in the log it DOES show that on every scan it DOES see the SSID that it should be connecting to:

21:12:44 wireless,debug Neodesha: must select network 
21:12:44 wireless,debug 00:0C:42:18:0A:FF: on 5180 AP: yes SSID OmalleyImplement caps 0x431 rates 0xff00 basic 0x100 MT: yes 
21:12:44 wireless,debug 00:15:6D:54:87:B5: on 5825 AP: yes SSID 8Up-cv caps 0x411 rates 0xff00 basic 0x100 MT: yes 
21:12:44 wireless,debug 00:15:6D:63:9D:2A: on 5805 AP: yes SSID 8Up-neo caps 0x421 rates 0xff00 basic 0x100 MT: yes 
21:12:44 wireless,debug Neodesha: 00:15:6D:63:9D:2A failed to join recently 
21:12:44 wireless,debug Neodesha: no network that satisfies connect-list,  by default choose with strongest signal 
21:12:44 wireless,debug Neodesha: failed to select network 
21:12:44 wireless,debug Neodesha: delaying scanning

It should connect to 8Up-neo. When it does connect, the signal is -71, ccq is 98% or so, and the SNR is about 30dB. It should be working perfectly, with numbers like that.

I’m seriously starting to think that it’s the XR5 cards, I saw another thread with exactly the same problem on this forum, and now what you’ve said.

We’re replacing them tomorrow and we’ll see what happens.

I’ve also sent a supout.rif to support, to see if they can see anything in there.

4

Sounds like interference. Especially since the CCQ improved after disabling CSMA. Be on the look out for other 5ghz OFDM sources.

5

In my case I tried every single freq there was on 5ghz even with superchannel. No matter what I chose it worked great for a while then crapped out 6-24hrs every time. Then I could go scan or mess with something and it would come back up. This one has just been weird.

Scott

6

I am having a similar problem to you. Link flapping every few days. When I perform a scan it comes back with the ssid if the remote end with a good signal but will NOT associate.The last thing that I have done which has kept the link up for 4 days is to reduce the data rate to 9Mb. Try it and let me know how you get on. Running 3.7 on both sides. Link distance 24k, tried numerous channel’s/Superchannel.

Brendan

7

Hi!

Check the AC adapter if the voltage drops , im using only (now) 48 Volt 7 Amps or 24 volt 12 amps, and i newer have problems with drop outs. you can check if you lower the output from the radio cards ,then it probably not disconect.

//Rickard

8

I never have problems with all my other links too - just this one. Swapped out one side today - antenna - cable radio card etc… will see.

Scott

9

I appreciate everyone chiming in, it’s always nice to see a community doing it’s thing :slight_smile:

In my case I tried every single freq there was on 5ghz even with superchannel. No matter what I chose it worked great for a while then crapped out 6-24hrs every time. Then I could go scan or mess with something and it would come back up. This one has just been weird.

I also tried every channel, on 5Mhz, 10Mhz, 20Mhz, and 40Mhz channel widths.

I am having a similar problem to you. Link flapping every few days. When I perform a scan it comes back with the ssid if the remote end with a good signal but will NOT associate.The last thing that I have done which has kept the link up for 4 days is to reduce the data rate to 9Mb. Try it and let me know how you get on. Running 3.7 on both sides. Link distance 24k, tried numerous channel’s/Superchannel.

I had also tried locking rates down - it didn’t help much, if any, in my case.

Check the AC adapter if the voltage drops , im using only (now) 48 Volt 7 Amps or 24 volt 12 amps, and i newer have problems with drop outs. you can check if you lower the output from the radio cards ,then it probably not disconect.

Originally I was using 48v 350mA on the A side and 18v 900mA on the Z side. In the process of troubleshooting we replaced the 48v 350mA power supply with a 48v 500mA power supply, and it did not have any impact whatsoever. Lowering the output power of the XR2 did not have any impact on the symptoms.

I never have problems with all my other links too - just this one. Swapped out one side today - antenna - cable radio card etc… will see.

Well, this is sortof what I ended up doing. I switched the XR5 on the A end (the unit which had another SR5 in it) with an SR5 and now the link has been up for 27 hours and change - the longest it’s been up in the last 5 days.

Signal is -74/-77 SNR 26 CCQ 80% Nstream enabled CSMA enabled

At this point, I’m concluding that It’s a “bad” XR5 - with the number of other similar reports with XR5 cards I’m wondering if UBNT had a bad batch??

10

We solved our problem using 5Mhz channel width, but our troughput is now about 3Mbps… It is enogh for us, but I wish to have some more bandwidth… Any ideas ?

This is my http://forum.mikrotik.com/t/wireless-link-going-down/21003/1

11

500mA is not enough to power a 532, XR5 and SR5 reliably. And by replacing the XR5 with an SR5 you have reduced the power draw. This does not prove that the XR5 was faulty.

12

The SR5 uses MORE power than the XR5

13

So we’ve still been dealing with the same problem on this link for almost a year now. Basically we settled in to a pattern of it would run for a few days, start flapping (even though signal and SNR are great), we’d switch from “high band” 5.7Ghz to “low band” 5.3Ghz and it’s work for a few days, start flapping, and we’d switch back.

Yesterday, we switched over to an RB411 with a brand new XR5. exact same behavior.

I’m at a bit of a loss… I’ve tried every channel, every setting, and nothing seems to help. I just don’t understand how with a signal of -65, SNR of 34dB, and 80% CCQ, an interface can disconnect with “Extensive Data Loss”?!

14

Hi,

have the same problem with cm9 cards. The signal is stable at -76 and CCQ 87%.

10:56:26 wireless,info 00:0B:6B:81:D3:57@RF: lost connection, no beacon
s received 
10:56:28 wireless,debug RF : must select network 
10:56:28 wireless,debug empty 
10:56:28 wireless,debug RF : no network that satisfies connect-list,  by
 default choose with strongest signal 
10:56:28 wireless,debug RF : failed to select network 
10:56:28 wireless,debug RF : delaying scanning 
10:56:31 wireless,debug RF : must select network 
10:56:31 wireless,debug empty

the link work 1 - 15 hour stable and then disconnects.

15

´Fix frecuency use, on scan list.
Not use SR5 with XR5

16

hi,

i found a solution for me, adaptive noise immunity fix the disconnects and the CCQ is 20% higher than before… try it

greets JinX