LHG5 multi link, loosing speed somewhere.

RouterOS Wireless Networking
1

I’ve got 4 LHG5s setup as a multi link system as follows:
Ethernet->Lgh5#1<-nv2->Lhg5#2<-Ethernet->Lhg5#3<-nv2->lhg5#4->Ethernet.

Links are both 20Km. I get -65 to -67 on both links.
No noisy spectrum at all. It’s in a rural area with perfect los and no fresnel problems.

Running bridge between 1 and 2.
2 and 3 is connected by a switch close to each other.
And number 3 act as AP for number 4.
All wlan are bridged and on the AP I run WDS dynamic to bridge.
Connection tracking disabled
No firewalls, no dhcp servers or clients, no nat.
This should be a transparent link.

If I run bandwidth test between 1 and 2 I get steady 80mbit tcp with 20 connections.
Between 2 and 3 I get Ethernet 100Mbit approx as I should.
And between 3 and 4 I get at least 100Mbit.

But from 1 to 4 I can only get 27Mbit!?

I have tried changing frequency on both the bridge and AP. Same problem.
Switched from NV2 to nstream on one side. No effect whatsoever on throughput.

Is this a link related problem or could this be something else?

This is by first mikrotik PtP, please guide me in the right direction.

2

No need for WDS in your scenario. Try setting AP-bridge on APs, and station-bridge on stations.

Which frequencies and channel width are the PTPs using?

Which RouterOS AND Firmware (System > Routerboard) versions? Which Wireless package? (System > Packages, Wireless-???)

3

Try nstreme. Also 2 and 3 must not be close to each other. At least 5m separation or interference will ocrr,like now.

4

Im using 5180 on 3->4 and 5200 on 1->2.
I have tried to use others on the one thats on 5200 with no significant difference.
I want to use WDS on the 3-4 link because if this works out I will add one more client to number 3 in the tower.

Firmware is 3.30 and 3.29 and wireless is 6.36.3 on all.

LHG number 2 and 3 are really close to each other. And the angle difference is not more than 30 degrees.

But if i separate them with two channels as far as possible, I thought that it would not be a problem with interference.
If i set the frequency higher that 5295 on number 2 (The bridge) I cannot connect the client!

I will go and remount one of them (2 or 3) at a lower level, 5 meters lower if possible.
Only problem is that the tower is 40Km away by car, will do this asap.

5

5180 and 5200 are overlaping. You need bigger separation.

6

Changed to 5280 om bridge, no difference..

7

80mhz for plastic radios is to low. Until you put some distance between and some 400Mhz the link will not work.

8

Thanks Inox!
As I said, I could not change frequency above 5300-ish.
The default scanlist does not include anything above this. Added up to ocer 5800 and changed freq to 5770.
Now this works super! I get 90MBit all the way with bandwith test!

Thanks all for the help!

9

You don’t need WDS to joing more than one station, the advice of using Ap-bridge and station-bridge remains.

Click the System > Routerboard upgrade button to upgrade LHG’s firmware.

10

I have moved the antennas on the middle point apart and separated frequencies.
All have the latest firmware and radio versions.

With the internal bandwidth test i get around 80/90MBit.. Ok, this looks good.

But my client can only use approx 40MBit! Speedtest.net same result for a week now.
Tried to change the MTU on the links to 1600, no difference.

And what would changing from WDS to Station Bridge in reality do? I cannot understand why WDS should be a problem.

11

On a point-to-point link, WDS is no problem and it has the advantage that it makes the link more transparent.
(MAC addresses are unchanged across the link)
I would keep it selected.

Note that some clients cannot handle particular defects on a link in the same way. E.g. packet loss, packet
re-ordering, etc. Your own measurement has already determined the maximum rate of the link, but other
uses of the link (e.g. a single TCP connection) may result in a lower value. There is not much that can be
done about that when you cannot tweak the settings of the clients or replace them completely with better
operating systems, for example.

12

Changed to bridge. I have contacted the client to do some more testing.

13

I have a simillar problems on tdd links. It acts just like you said.

It can be antenna interference
First of all make sure that those antennas in the middle point are as far from each other as possible.

Or it can be half duplex problem
You can also try better switch or even router.

If you have antenna mounted close to each other it is obvious, if not thats gonna be a problem.