Throughput of one session MIMO bridge on MT

RouterOS Wireless Networking
1

Hi,

i have problem with throughput of downloading in one session.
Link is connected on -45/-43, CCQ 100%, visibility 100%, distance - over a dozen meters (for test reasons), noise floor -112, fresnel 100%, link connected with 300 Mbps Rates, platform RB711G-5HnD, antennas Jirous Gentlebox JC-320, ROS 5.19, FW 2.41, channel width 40 MHz, Chain 0 i 1 enabled, mode of connection is bridge / station bridge (but using VPLS i can’t see any visible differences).

When i’m using nstreme connection everything are works almost right - downloading with 1 session goes with 11 MB/s (acceptable result), ping with that load are on the good level (about 4 ms). Why almost? Because connection is interrupted every few seconds. Informations in log are “too many poll timeouts”. In this board i read to increase HW Retries. Ok, fine, i increased to 14 (maximum value). Effect? Connection is not interrupted every few seconds but every few minutes (with the same load, when i’m increase load to maximum the link is disconnecting after few seconds).
Unfortunately this state of matter is unacceptable. What is interesting on the bridges in my network, where are worst antennas, worst signals and N with 1 chain nstreme is superstable.

OK, there are two other ways - like 802.11 - here i can’t say so much because when i saw that transfer do not exceed 4 Mbps i stops test immediately.

Goes away it is only NV2. Technology which work stable in my network for a long time. The biggest defect of NV2 is ping with small throughput - when packet is going by few bridge’s which are NV2, ping of this packet is worst than DSL connection with interleaved mode :wink:. So i want to test NV2 at the end. Effect? Using default settings i received a speed of downloading which is 5 MB/s (TDMA Period Size 2 ms, Cell Radius 20 km). I tried looking for different solutions to reduce these two values to 1 and 10. In the effect speed increased significantly - from 5 MB/s to 7,8 MB/s. It’s quite good result, but having in mind number of bridges in network on the last base station can be problem to achieve 2 MB/s. Therefore, striving for the highest value that is possible to gain with NV2. At the moment, i will introduce this solution but I do not want to make that situation as the target. After uploading the 5.20 i haven’t got visible differences.

So here is my question - what can i do / change in settings of connection to increse speed to nstreme level using NV2 or what can i do to make rock stable connection using Nstreme?

Regards,
Colir

2
  • IMHO hw-retries doesn’t affect Nstreme.
  • Nstreme doesn’t like 802.11N, especially multichain one.
  • I would try to use lower TX-power. The cards can have troubles to send data with full power. Or if the test is indoor one you can eliminate some unwanted signal (reflected wawes)
  • yes NV2 can have long ping with when there is not enough traffic. If you have such low traffic you don’t need 300mbps link (Nstreme with 802.11A would be better ?)
  • if you want to have higher througput in NV2 you have to increase TDMA period size. I didn’t tested in PtP environment so I am not sure what happens to ping time …
3

Hi,
thanks for your reply.

  • IMHO hw-retries doesn’t affect Nstreme.

Why? So why i get an effect after increase hw-retries?

  • Nstreme doesn’t like 802.11N, especially multichain one.

I don’t know why nstreme doesn’t like 802.11N?

  • I would try to use lower TX-power. The cards can have troubles to send data with full power. Or if the test is indoor one you can eliminate some unwanted signal (reflected wawes).

I made that test in the garden, tx-power was 0. Distance of that link was 15 meters.

  • yes NV2 can have long ping with when there is not enough traffic. If you have such low traffic you don’t need 300mbps link (Nstreme with 802.11A would be better ?)

I really know about it. I have about 150 mikrotik devices in my network and i have a little bit of experience.

  • if you want to have higher througput in NV2 you have to increase TDMA period size. I didn’t tested in PtP environment so I am not sure what happens to ping time …

I know about it but i forgot to change that settings when i was doing the test.

4

Ah sorry - I rechecked the hw-retries and since 4.x the nstreme is using the hw-retries.

  • Nstreme doesn’t like 802.11N, especially multichain one.

I don’t know why nstreme doesn’t like 802.11N?

It is my experience that when I enable 802.11N the nstreme PtP link starts to have problems. And on Internet you can find other people with the same problem too. Althought there are success stories too. In my case the nstreme with N enabled can look better for a while (increased throughput) but in longer term the problems (disconnects periods with problematic throughput) are too big.