I was wondering if someone may know how to assist with a problem I have with brand new XR9 cards. I’ve set up a single link from one of my towers to my house using directional yagi antennas at both ends. The shot is only .87 miles long, with about 3-4 lines of trees in the way, not that bad. I’m using an RB433UAH at my house and an RB333 at the tower. The link is pretty decent as far as dB (74dBm) using 2442 (922) - 10MHz Channel Width. The SNR however is only about 18dB and the Tx/Rx CCQ is only at about 50%, which very well could be a part of my issue. The problem I’m having is that the link will stay up as long as I don’t try to use the Internet or pass any significant amount of traffic (mainly uploading). For instance, at the office when I try to Winbox into the MikroTik at my house, the connection immediately drops out from an 18Mbps/18Mpbs link and it just goes away. It immediately returns when I stop the data. I don’t believe it to be an issue with the Routerboards because file transfers directed to them via Ethernet doesn’t affect the link at all. It’s only when data passes through the wireless. Does anybody have any idea what causes this? Bad cards/CCQ too low, etc.??
syndrift:
Welcome to the Mikrotik forums!
There are several things that you might try…Loss of connection is usually a sign of interference. Here are my best suggestions at fixing this link
- Try other channels. Use the Freq usage and scan tools to help you find a clean channel. In our environment 2432 and 2427 are usually the cleanest
Set HW retries on the Advanced Tab to 15 on both sides.
Enable NStreme (on both sides starting with the client). Start with these settings - Experiment to see what the best results are. Enable polling, Set framing policy to “Exact Size”, Set framing size to 512 (The lower this number, the more robust the connect will be but the throughput will be slower…you can try increasing it until you see it start disconnecting…then lower it back down.)
If your SNR is around 18 db…I’m guessing your signals are probably in the high 60’s to low 70’s. On clean channels you should be seeing 5 to 12 mb throughput at those signals.
If the above changes don’t help…you may need to increase your gain (i.e. bigger antennas, tripods to get higher, etc.) to get the results your looking for.\
I know that this sounds odd…but you might also try using a 20mhz channel instead of 10. Your signal appears to be strong enough to support it and I’ve seen situations were it actually helps.
Also note that 900mhz in most environments is going to need more attention than 2.4…meaning you’ll want to login and check on it frequently. Because there are so few channels…the environment will be constantly changing around you. It’s more of a cat and mouse game than with 2.4 or 5ghz.
Hope that helps!
Thanks for the response! Nstreme is already enabled, I actually noticed an improvement when I enabled it. So far I can only connect with 2437 and 2442 (any channel width) and with full 20MHz channels, my CCQ drops all the way down to 8-12%. I do think however that the shot can be tweaked more by using a better antenna and some better aiming at the tower side since it’s a directional shot and is a little more difficult to aim. I will also go and make the other changes you spoke of, and see if it can make any difference.
I take it that its normal for a wireless link to just completely drop if the data loss is too severe…which would make sense, it’s just frustrating! 
Thankss again for the response! I will post back once I implement some of the changes.
Good news! Changing the framer-policy to exact size and modifying the framer-limit to a lower number did actually improve the shot enough to where it no longer drops out when I use the link to pass data. Although the throughput did decrease, it appears to be stable just from the fact that running an upload bandwidth test CPE to AP doesn’t cause my link to drop anymore. This, accompanied with the hardware and aiming tweaks I plan to make should ultimately resolve my issue. I appreciate the advice!
Glad to hear that helped!
Hi …
I use XR9s (1 AP, 2 clients), nlos both clients (hills with dense tress), 5MHz bw instead. ROS is now 5.0, a 411AR as AP, 433UAH one client and an old WRAP as the second client.
But I never had drops due to traffic. Some period due to interference, until now I don’t know if in-band (rfid devices, cordless phones, etc) or out of band (a nearby cell tower).
While playing with the ROS 5.X release candidates and NV2 this drops increased and I didn’t want to went back to V4.17 'cause I want to use pcq burst feature, only avialable at 5.X. Drops increased no matter which format I use: 802.11, Nstream or NV2.
I ordered an AirView 900M EXT to inspect the spectrum and mainly to serve as a selective level meter because to get rid of some possible out of band interference I designed a 7 pole interdigital filter for 902 … 928MHz. I have a noise source that generates white noise from 100KHz till 26GHz, 33dB ENR so I’ll use it as a signal source to adjust the filters.
Since every time I lost one of the clients, changing freq from 2437 to 2442 and vice versa if necessary solves the problem for a couple of hours.
Then I wrote a script to change this freq automaticaly as soon as authenticated-clients at 900MHz interface was less than 2. Thought that this “solution” was enough until I have the filters ready for use.
While inspecting the /interface wireless monitor (using terminal) I saw between several monitored parameters one that call me attention: current-ofdm-errors.
It was ranging from 100 to 300 and I didnt’t know nothing abt it, if it is a relative reading, degrees, etc. I assumed it is very “hardware” related. So any interference will not be masqueraded there. May be masquereded later by equalizers, FEC, etc.
Well, 411AR has its built in 802.11B/G transceiver which I use as AP too. Was running at 2422. XR9 switching between 2437 and 2442. Overlapping channels, isolation problems because XR9 IF is 2.4.
I changed 411AR built in radio to channel 13 (we have it on our country channel plan). SNR, CCQ and signals doesn’t changed a bit. BUT: current-ofdm-errors dropped from 100~300 to … 1~5.
Since then, a single drop each client. That lasts 2 seconds each and that’s it.
Nothing special on the card settings: Nstrem enabled, polling enabled, csma disabled, frame limit 3200, exact size, default power, mode only G, datarates manually configured on AP (6, 18, 24, 36, 48, 54, basic 6) and default on clients, noise reduction enabled on all XR9 (if disabled this current-ofdm-error measurement does not came up), distance dynamic, periodic cal enabled, hw retries 15, Disconnect Timeout = 0.
Regards