Today I finished some extensive testing on a 4 km backhaul between a Netmetal and 911G-5HPacD
I started with v.6.40.5, tested v.6.40.8 and ended with latest 'current' v.6.41.1
I tried both 'n' protocol as 'ac' for all three working modes. nstreme, 802.11 and NV2.
First in v.6.40.5 I tried to find the best setting for each of the working modes by altering some of the fine tune settings (preamble, guard interval, Hw retries)
All tests done from behind the link connected routers (SXT-ac and Sextand) towards a rb750G r3 upstream.
All tests done with a single stream and only the download (from rb750 towards the SXT/Sextant)
Each test ran at least for 2 full minutes and done over a 'live' link that also has some customers traffic.
The link runs in a region with plenty of other 5Ghz usage so nowhere a real 'quiet spot' is found in the spectrum. The one we used we found after days of trying for the best...
2 major conclusions and some minor to be made after some 30 tests (4 hours! of work) are:
1. Upgrading (both link units) from 6.40.5 via 6.40.8 towards 6.41.1 does not bring spectacular improvements. Latency in general goes down a bit, but speed not. In fact the highest consistent throughput is measured in nstreme v.6.40.5!
2. Shocking is that in all tests nstreme outperforms NV2 by 200%! And 802.11 is a good follow-up to nstreme but slightly slower. (Some 5-10%). The only thing NV2 is good in is latency. That is consistently around 3-5 ms where nstreme is around 25 - 35 and 802.11 is around 30-45 ms.
3. Difference between 'n' and 'ac' is marginal. 'ac' is slightly better in throughput but more variable then in 'n'. The ping though is slightly more stable where in 'n' it is more variable.
4. The 'nstreme' protocol can take up to a minute to connect and looks like it needs a 'learning curve' before it becomes stable. NV2 and 802.11 make almost immediate connection (station has frequency set in the scan list). NV2 builds the highest modulation sightly faster then 802.11.
5. 'nstreme' seems to have more issues in reaching, and keeping, the highest modulation rate, but overall the throughput, even when modulation drops for a little while, is still higher then NV2.
I have done this test after several others claimed NV2 wasn't as good as it could be. Also after I myself on several links saw the same effect that 802.11 or nstreme is better.
This is still a test that doesn't means it is representing for all networks, although I think my network is pretty typical.
Imho Mikrotik needs to send their NV2 (for backhauls, this is a backhaul link. It might well be on P2MP the result is different. Although also there I found 802.11 outperforming NV2 in some of my AP's) technology back to the draw board and do a hell lot more of testing.
I made a spreadsheet with the findings of the test. In fact much more variables could be tested too. But the matrix over 3 different software versions, 3 different protocols and 3 different IEEE standards ('n' or 'ac') together with the several variables for each of the protocols that can be set has force me to set some variables fixed for all tests or only test them in some occasions.
If we think we have at least 5 (or more) variables per protocol (3), times 2 standards ('n' and 'ac'), times 3 ROS versions then we already talk about 5 x 3 x 2 x 3 = 90 different setups........
It's just too much to test these all........ (And every link is different again!)
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Rudy R. Puister
WISP operator based on MT routerboard & ROS.