18km PtP wireless link issue

RouterOS Wireless Networking
1

Hello,

I have wireless link at 18km distance. I’m using RB435G, R52Hn wireless cards, 0.5m coax cable with RP-SMA connectors (on both ends) and dual polarized Ubiquiti 30dB rocket dish. I have the same configuration on both ends.
I’m getting the following error every hour, and some times every few minutes:

…
17:19:40 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: disconnected, too many poll timeouts
17:19:40 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: disconnected, too many poll timeouts
17:19:43 wireless,debug turija-bozevac: 4C:5E:0C:10:3D:69 attempts to associate
17:19:43 wireless,debug turija-bozevac: 4C:5E:0C:10:3D:69 in local ACL, accept
17:19:43 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: connected, wants bridge
17:19:43 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: connected, wants bridge
17:25:22 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: disconnected, too many poll timeouts
17:25:22 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: disconnected, too many poll timeouts
17:25:24 wireless,debug turija-bozevac: 4C:5E:0C:10:3D:69 attempts to associate
17:25:24 wireless,debug turija-bozevac: 4C:5E:0C:10:3D:69 in local ACL, accept
17:25:24 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: connected, wants bridge
17:25:24 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: connected, wants bridge
17:27:09 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: disconnected, too many poll timeouts
17:27:09 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: disconnected, too many poll timeouts
17:27:11 wireless,debug turija-bozevac: 4C:5E:0C:10:3D:69 attempts to associate
17:27:11 wireless,debug turija-bozevac: 4C:5E:0C:10:3D:69 in local ACL, accept
17:27:11 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: connected, wants bridge
17:27:11 wireless,info 4C:5E:0C:10:3D:69@turija-bozevac: connected, wants bridge
…

Here is the AP configuration:
/interface wireless
set [ find default-name=wlan1 ] band=5ghz-onlyn basic-rates-b=“” channel-width=
20/40mhz-ht-above comment=“Link iz Turije ka Bozevcu (Bozevac predaje)”
country=debug default-authentication=no disabled=no frequency=5765
ht-basic-mcs=mcs-8,mcs-9,mcs-10,mcs-11 ht-rxchains=0,1 ht-supported-mcs=“mcs
-8,mcs-9,mcs-10,mcs-11,mcs-12,mcs-13,mcs-14,mcs-15,mcs-16,mcs-17,mcs-18,mcs-
19,mcs-20,mcs-21,mcs-22,mcs-23” ht-t
mode=ap-bridge name=turija-bozevac p
configured ssid=boz-tur-tlx supporte
1Mbps wireless-protocol=nstremeSignal levels are -54/-59 dBm, CCQ: 62/65 % (sometime higher).

I have tried multiple configuration setups. I have switched also AP/client sides. I have also enabled debug county, so I can try to get noiseless channel as much as possible.
I’m also not running firewall or something like that on them, so CPU is idle.

I will appreciate every advice I can get.

2

Try using NV2.

3

I am not an expert, between the 2 chains there is -5dBm difference, maybe need to align a little bit better, but this is my opinion, this is my recommended scenario for you:

A point: bridge
B point: station-bridge

Firstly: 802.11 N, and then you should try out with NV2 as well.

4

Try this configuration.

Other devices but the same config.

http://www.wirelessinfo.be/index.php/mikrotik/pages/omnitikpp

Look to printscreens a made

5

Anyway, i have got an 1km Sxt link, between the 2 chains there is 5 dBm different sometimes.

Chain0:-65dBm
Chain1:-60 dBm

But depend on the frequency, i think the chains are ok, and the pigtail as well.

There is a local WISP, and this area is very noisy, when i scan on the Sxt at both sides “see” 30-40 AP, impossible to achieve good performance.

6

@trackboy The chains looks excelent
Chain0 = vertikal polarisation
Chan1 = horizontal polarisation or vice versa
This is that signal difference

7

I would recommend to upgrade both ends to RouterOS v6.11 and then try to reset the wireless interface configuration by using such command:
/interface wireless reset-configuration wlan1

Then configure the settings you only need.
Also I would recommend to try out Nv2 wireless protocol.

8

Here is the AP configuration:
…wireless-protocol=nstreme

1.Never RocketDish :slight_smile: I dont like it :slight_smile: personal… 30dB rocket dish gives 5-6 degree, good for 18 km but when there is no noise… If you have noise best fit is antenna with 2-3-4 degree, like 34dB rocket dish
2. After this is what u have reset the config on both side and start again, but with no nstream, NV2 is pretty much ok.
3. Before all, first establish the link on band=5ghz-a, frequency-mode=superchannel, channel-width=20mhz, Site1 - AP-br, Site2 - station - pure config… and use scanslist like 5000,5010,5020…
4. After the link is established, start looking for the best frequency
5. If /ping site2 interval=0.1 size=10000 goes well - U have found the perfect frequency if there is non because of too much noise go with a smaller packet
6. now turn NV2 on both sides

9

Thank you all for advices!

I have tried nv2 protocol, but latency isn’t very good. I personally got better speed with nsteme. I’m getting around 120-130Mbps UDP traffic in one direction, and also pretty decent pings (15-30ms) while bandwidth test is running at that speed. Maybe I haven’t configured nv2 properly.

I have also concerns about fresnel zone. I have done theoretical link calculation for this setup, and it’s on the edge. Is there some way I can check if I have issue with frensel zone?

10

Make schematic plan I m what confused?

Have you troubles with the rocketdish?

11

Here is the results that I got from link calculator:
18km ptp link.png

12

Ok thanks for that but have you troubles with the rocketdish?

Have you setup the ack-timing (distance) in advanced settings?

13

Thank you for your reply.
I don’t think I have troubles with rocket dish, but maybe I’m wrong.

Regarding to ack timeout, I’m not sure how to set it when it’s in nstreme mode.

14

Try to set hw. retries to 15 usually can help in this situation, also for nstreme can try different framer policy and framer limit or switch to nv2 work more stable on N wireless interface.
Also you can try new wireless package but is beta for now I try on 23km p2p for now experience is very good if you have time and possibility to experiment.

Pozdrav…

15

I have already set hw retries to 15. I have tried nstreme with exact size setting it from 2000, 3000 and right now it’s on 4000. For me NV2 isn’t working good, or maybe as I said I didn’t configure it properly. I’m getting much higher pings with it comparing it to nstreme protocol. Also I have notice CCQ is lower on nv2.

When you are saying new wireless package, are you referring to 6.11 version?

Hvala!

16

Yes 6.11 but need to install separate wireless package look on download page http://www.mikrotik.com/download, also this is beta package installing disable regular wireless package but be careful switch back an do disabling this new package and must enable regular package to wireless work again also I have problem switch back to regular all setting for wireless remove backup configuration if you this thing.
For now I have this new package on this one link it is not very important and easy access to device on both side good for testing a also on home 951G working good.
On this 23km link have up time 5 days no disconnect for now using regular 802.11 protocol will see what happen for now is good. Before sometime have disconnection but now very often possible weather condition cause disconnect, will see 5 days for now.

17

Thank you for letting me know. I will stay away from beta release for now, since there is no easy way to access on hill :slight_smile:.

I’m still looking for advice for this problem. If someone has an idea what can be wrong with this setup, please let me know.

18

I saw ht-rxchains=0,1, what is happening with ht-txchains ???, are they set to 0,1 like rxchains

Next time when u go to the hill get a binoculars with u and take a look at the other end… do u see it, cause what I see on the diagram u gave is that you are on the edge and if there are some trees u may have a bigger problemo :slight_smile:

19

Can I ask how are you measuring performance is it from site A router to site B router or the router before point A and router beyond point B, also you have freznel zone issue at 12kms from point A, to solve increase antenna height(s) at either or both point A + B, reduce wireless scan list from default to +/- 20Mhz above below AP frequency, so for example AP=5765 set wireless scan list to 5745-5785, there is no point in scanning from 5180 to 5865 when you are using 5765.

20

I just want to let you all know that we have fixed this issue. We have aligned better antennas by using two crews or both sides at the same time. We have increased signal by few dB. Now we are using NV2, and everything works fine now. Only issue that we got with NV2 is a few ms worst pings, and a little bit lower bandwidth. Overall we are happy with link now.
Thank you all for helping!