Plain 802.11-an better then NV2!

1 AP rb911G-5HpnD on a 12dBi omnidirectional antenna.
27 clients. Mixture of Mainly SXT-L, one SXT-Lac and one SXT-sq5ac and rb911 and some 711’s and even still 3 411’s.
AP in bridge mode, CPE’s routing with PPPoE on wlan1
Management network by dhcp server on RouterBOARD 750G r3 behind AP with vlan2
vlan2 interface on CPE’s wlan1 with dhcp client.

Tests are done by Mikrotik’s bandwidth test from CPE with 1 connection only, tcp and download.

40Mhz channel width

AP running ros v6.42rc52 and fw updated to 6.42rc52:

adaptive-noise-immunity=ap-and-client-mode band=5ghz-onlyn basic-rates-a/g="" channel-width=20/40mhz-Ce disconnect-timeout=3s distance=dynamic frame-lifetime=0 guard-interval=long ht-basic-mcs=mcs-7,mcs-8,mcs-9 ht-supported-mcs=mcs-7,mcs-8,mcs-9,mcs-12,mcs-13,mcs-14,mcs-15 hw-fragmentation-threshold=disabled hw-protection-mode=none hw-protection-threshold=0 hw-retries=3 interworking-profile=disabled keepalive-frames=enabled l2mtu=1600 mode=ap-bridge nv2-cell-radius=10 nv2-downlink-ratio=75 nv2-mode=dynamic-downlink nv2-noise-floor-offset=default  nv2-qos=default nv2-queue-count=2 nv2-security=enabled on-fail-retry-time=100ms preamble-mode=long rate-selection=advanced rate-set=configured rx-chains=0,1  security-profile=AP-E supported-rates-a/g=12Mbps tdma-period-size=3 tx-chains=0,1 wireless-protocol=nv2 wmm-support=enabled

I left not relevant items out.
AP can be switched between wireless-protocol=nv2 or 802.11

CPE’s are all set accordingly and all run on v6.41.3 and fw 6.41.3. Only SXT-sq5ac is running on 6.42rc52 too with latest fw. (6.41.3 doesn’t support PPPoE yet for ‘arm’ device!) :

adaptive-noise-immunity=client-mode band=5ghz-onlyn basic-rates-a/g=6Mbps bridge-mode=enabled channel-width=20/40mhz-Ce compression=no default-authentication=no disconnect-timeout=3s distance=dynamic frame-lifetime=0 frequency-offset=0 guard-interval=long hw-fragmentation-threshold=disabled hw-protection-mode=none hw-protection-threshold=0 hw-retries=3 interworking-profile=disabled keepalive-frames=enabled l2mtu=1600 mode=station mtu=1500 multicast-buffering=enabled multicast-helper=default nv2-security=enabled on-fail-retry-time=100ms preamble-mode=long security-profile=AP-E tx-chains=0,1 wireless-protocol=any wmm-support=enabled

Most other setting are by AP. RTS/CTS is set to work always in 802.11 mode.

This network runs in an area where basically every frequency has some other Wifi AP working. Hence interference but the chosen channel is as free possible.

On a live network but little usage, I open 4 clients.
From each CPE I open a single stream tcp download from the rb750gr. In this network no queues or priority settings in place.
so the stream runs from the rb750gr over a gigabit cable though a Netonix switch by gigabit to the AP and then by wireless towards the clients.
All clients connect basically in a -38 to -55 range and the worse is -57
Clients for the test all run with low 50’s or better.

Test 1. 802.11 ‘n’;
When one client start, 80 to almost 100mbps download. When second client start 1st looses some but both on sort of 30-40Mbps. Add no. 3 and no. 4 each individual speed goes down somewhat further but still they all fluctuate between 20 and 30Mbps.
Meanwhile the AP shows a throughput running up to a 115mbps average with some peak of 130Mbps.
All 2 minutes test.

Test 2. NV2, variable downlink 75%:
One client starts with some 40-50mbps, peaks up to 70 max. When more clients are add, each get less. In the end they all four run with only some 10-20mbps.
Meanwhile the AP shows a throughput running up to a 70mbps average with some peaks nearing 115mbps. But overall much more unstable as in Test 1

Test 3. NV2, fixed downlink 75%:
Sort of same as Test 2 but everywhere and overall we lost another 5-10% on capacity.

My conclusion: 802.11 ‘n’ beats NV2 even on a multiple CPE high interference network.

To be honest, in preparation of a swap of 3 other networks that now run Mimosa we tried first with SXT’s ac’s in Mimosa ‘interop’ mode which is in fact plain 802.11 with fine tuned RTS/CTS and we were already blown out of our shoes by the immense boost in speed we got on the clients. I partially blamed that on the more powerful Mimosa AP combined by the more powerful SXT-ac’s but after reading some posts by some guys somewhere on the net that do a lot of testing I already got the impression that the 802.11 with RTS/CTS isn’s to bad as what every vendor makes us believe. (They all try to talk us into their proprietary tdma protocol and if succeeded less change a client will walk to the competition again…

My next project will be now to exchange all ‘n’ units in this ‘test’ network by ‘ac’ mode CPE’s which is going to take a month or so.
In the mean time Mikrotik should do its best to work even more on their latest NV2 improvements!

When all my network is ‘ac’ I hope to come close to what we have with Mimosa now, 100, 150Mbps or even 200mbps to the client! When this can be achieved I will be back supporting 100% Mikrotik.
Because after all, a 30 client P2MP ‘ac’ network of Mikrotik is still only costing a fraction of what eCambium, Mimosa are costing. We are still cheaper then ubnt…

Strange nobody has comments on this? This is a BIG surprise!

Even Mikrotik staff should raise an eyebrow to learn their tdma is not as good as plain 802.11 an with RTS/CTS.

If we then read about the improvements in the 802.11 ac standard in regard of frequency re-use and interferencia avoidance technology I am wondering if NV2 can meet up with the standard protocol enhances…

The scary think is, that everybody knows that…
That’s the reason we stop deploying Mikrotik, because Competior is able to deliver more and stabler Bandwidth…

Mikrotik is working on Nv2 but this changes don’t work for us, I postet a lot of screenshots und the changing thread..

runing Omnitik AC since 2 months connected SXTqac on plain 802.11
link uptime 33days (reseted only because of wlan protocol change to 802.11)
my speedtest on 40mhz channel ( 360~400mbps PHY rate)
speedtest80211ac.jpg
nv2/nstreme wouldn’t give me half of it.

Looks like you have absolut clean spectrum

Distance Omnitik - Sxt?
Allowed Eirp?

spectrum is quite noisy (omnitik case) distance is minimal, 100metres, but it’s about protocol,
I struggled with nstreme, sometimes switched to nv2 when mikrotik revealed next super optimalization of nv2 protocol. Did it so many times,
swapped hardware both sides, eventually turned to 802.11 mode.
It really works for me.
ofcourse watching 4k streams is no problem witch such speed.
btw omnitik is powered by wap60g, so I wish I could squeeze some more of ac gear, just because omnitik is supplied with ~1gig (mcs8@60G) of bandwidth :slight_smile:

We are seeing the same thing, we just got hundreds of sxt5 sq ac’s lhg5ac’s in and with our omnitiks they perform terribly on nstreme and nv2. 802.11 exceeds them which is sad. It doesnt matter if its on wireless N mode or AC same results; what I am seeing is very poor rx and tx ccq from AP. Even with the new RC firmware doesnt make a difference. Aweful performance I hope they fix the ptmp with nv2/ nstreme for the ARM boards. Untill than we have to stick with wirless N clients. Unbelieveable mikrotik sends them out with that sort of issues. … btw yes the spectrum is clean. NV2 settings were 2ms dynamic downlink at 80 and cell radius 15km.

Does this mean 802.11 RTS/CTS works properly now? About 2 years ago it was broken on AC devices (NV2 was bad too, Nstreme was not perfect either but best of them all). The symptoms with RTS/CTS were like it was not avoiding collisions - works fine most of the time with high MCS rates, and just sometimes during peak hours everything almost stops (low MCS rates) usually for a few minutes until traffic is reduced (customers TCP connections time out etc.) and then it slowly recovers. The low MCS rates (despite strong signals and, in my case, clean licensed spectrum in 6GHz band) could be explained by the cycle: collision (no ACK) → retransmission at lower MCS → higher probability of another collision (due to longer air time at lower MCS) - enabling or disabling RTS/CTS on all stations made no clear difference. It was a bit more stable (at the cost of speed) when ACK distance was set manually to about twice the real distance - some subtle timing issue?

In AP..
RTS/CTS
CTS to self
?

802.11 CSMA/CA or NV2/TDMA are like round-about and traffic lights in car traffic.
Which one gives better throughput?
It depends how the traffic distribution and intensity is.

With traffic lights (not the real smart implementations) you always have some chance on fixed wait time, not the case with a round about.
With very heavy traffic coming from all sides, you almost don’t get on the round-about, creating large queues, and impaired throughput.

It’s the same story as with ethernet CSMA/CD versus token ring … had major discussions in the 80’s-90’s with IBM adepts.

Same with the 2 wireless implementations. 802.11 and TDMA

  • 802.11 transmits whenever it can. Good total combined throughput highly depends on large transmit blocks (aggregations) as the intertransmit gaps are fixed and are just loss of airtime.
  • nv2 has centrally managed fixed transmission slots. Intertransmission slots are smaller, so smaller transmission blocks are feasable, with no major throughput losses.


    Which is better? It depends doesn’t it.
    802.11 with large A-MSDU and certainly large A-MPDU will make effective use of airtime.
    AFAIK NV2 has no such thing as A-MSDU and A-MPDU.
    The well known lower performance of the WLAN driver can be explained by it’s small A-MSDU (MPDU) and A-MPDU. These size values are visible in the beacon.

https://dot11ap.wordpress.com/a-mpdu-vs-a-msdu/
https://inet.omnetpp.org/docs/showcases/wireless/aggregation/doc/index.html

You do know that was a response to a 6-year old thread ??

Later on yes, just responded based on #9, so it came in my “active topics” list, and I was tuning (MT<->GL.inet) connection.
Only saw that initial date later.
Problem is still very actual. Lots of OpenWRT problems (GL.inet, Cudy) even with newest versions like 23.03 … giving " lmac[0] Error, msdu index reach maximum limit, 31" problems with MT uplink.
OpenWRT forum asks to reduce the AMSDU limit parameter in MT AP. Must be a joke. (That 8192 value with Winbox is not used in ROS, AFAIK from the MT beacons)

I am very grateful for your response, always so thorough. My apologies for reviving an old conversation.

I found myself in need and this was the first thread I came across. I was having issues with my NV2 network and ended up switching everything to 802.11 with RTS/CTS enabled on the clients, setting the hardware protection threshold to 512. On the AP, I left those settings as “none.”

Now, my client is achieving stable in-game pings of 32ms compared to the previous 80ms. I’ll now look into optimizing AMSDU and AMPDU values to fine-tune my network further.

Thank you again for your help!

Welcome back :slight_smile:

RTS/CTS on the AP was off, but that shouldn’t really matter much, since all stations can hear the AP, it’s just that stations often don’t hear each other (hidden node) that’s why they need RTS/CTS - at least, that’s my understanding. I’m not sure in what situation “CTS to self” on the AP would help. NV2 seems to have improved in the meantime, though Cambium ePMP1000 in 6GHz seems to work better. Too bad MT seems to have stopped development of 60GHz products. If there was something line nRAY XL with support for all 6 channels (longer range), 31 stations per AP, and 5GHz backup - I wouldn’t have to start using yet another proprietary super-expensive and vendor-locked-in radio system (UBNT Wave) which still does some things poorly (can’t connect to existing 5GHz AP for backup to save some already crowded spectrum, no MAC ACL to force stations to connect to the correct sector, no RSTP).