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CCDKP
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Joined: Fri Jan 28, 2011 11:24 pm
Location: Midwest, United States

SXT NV2 Extension Channel Problems

Thu May 05, 2011 11:31 pm

I recently picked up a pair of SXT's to try out. This is my first venture into non-802.11 wireless, and i'm still pretty new to 802.11n in general, so please bear with me.

I originally started with the tutorial from wispforum.com (http://www.wispforum.net/entry.php?5-Ho ... ode-Part-I), and everything was going great until I attempted to change the HT Extension Channel setting. With no HT Extension Channel set, I get a very stable link that easily handles 50Mbit full-duplex. Once I enable an HT Extension Channel, ping jumps all over the place and the moment I start pushing non-trivial data (+1Mbit), the link disconnects with either a "medium-access timeout" or "control frame timeout" error.

I have already tried multiple channels, switching between Above and Below. There is no external 5.8GHz interference (checked with a spectrum analyzer). Disabling extra AMPDU properties had no effect.

The setup:
Image
The two radios are SXT-5HnD running 5.2 firmware. They are mounted on tripods, roughly 50m apart, with a clear line of site, in an unused portion of our office. The TX power turned down to 1 dBm on both. All bandwidth and link quality testing is performed by a pair of 750G's on either side of the link (.2 and .4 above)

Link status before and after applying Extension Channel:
ImageImage

Wireless Configurations:
AP:

/interface wireless
set 0 adaptive-noise-immunity=none allow-sharedkey=no antenna-gain=16 area="" \
    arp=enabled band=5ghz-onlyn basic-rates-a/g=6Mbps bridge-mode=enabled \
    channel-width=20mhz compression=no country=no_country_set \
    default-ap-tx-limit=0 default-authentication=yes default-client-tx-limit=0 \
    default-forwarding=yes dfs-mode=none disable-running-check=no disabled=no \
    disconnect-timeout=3s distance=indoors frame-lifetime=0 frequency=5745 \
    frequency-mode=manual-txpower frequency-offset=0 hide-ssid=no \
    ht-ampdu-priorities=0,1,2,3,4,5,6,7 ht-amsdu-limit=8192 ht-amsdu-threshold=\
    8192 ht-basic-mcs=mcs-0,mcs-1,mcs-2,mcs-3,mcs-4,mcs-5,mcs-6,mcs-7 \
    ht-extension-channel=above-control ht-guard-interval=long ht-rxchains=0,1 \
    ht-supported-mcs="mcs-0,mcs-1,mcs-2,mcs-3,mcs-4,mcs-5,mcs-6,mcs-7,mcs-8,mcs-9\
    ,mcs-10,mcs-11,mcs-12,mcs-13,mcs-14,mcs-15" ht-txchains=0,1 \
    hw-fragmentation-threshold=disabled hw-protection-mode=none \
    hw-protection-threshold=0 hw-retries=7 l2mtu=2290 mac-address=\
    00:0C:42:84:5D:79 max-station-count=2007 mode=bridge mtu=1500 name=wlan1 \
    noise-floor-threshold=default nv2-cell-radius=30 nv2-noise-floor-offset=\
    default nv2-preshared-key="" nv2-qos=default nv2-queue-count=2 nv2-security=\
    disabled on-fail-retry-time=100ms periodic-calibration=default \
    periodic-calibration-interval=60 preamble-mode=both proprietary-extensions=\
    post-2.9.25 radio-name=SXT-test-AP rate-set=default scan-list=default \
    security-profile=default ssid=SXT-test station-bridge-clone-mac=\
    00:00:00:00:00:00 supported-rates-a/g=\
    6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps,48Mbps,54Mbps tdma-period-size=2 \
    tx-power=2 tx-power-mode=all-rates-fixed update-stats-interval=disabled \
    wds-cost-range=50-150 wds-default-bridge=none wds-default-cost=100 \
    wds-ignore-ssid=no wds-mode=disabled wireless-protocol=nv2 wmm-support=\
    disabled

Station:
/interface wireless
set 0 adaptive-noise-immunity=none allow-sharedkey=no antenna-gain=16 area="" \
    arp=enabled band=5ghz-onlyn basic-rates-a/g=6Mbps bridge-mode=enabled \
    channel-width=20mhz compression=no country=no_country_set \
    default-ap-tx-limit=0 default-authentication=yes default-client-tx-limit=0 \
    default-forwarding=yes dfs-mode=none disable-running-check=no disabled=no \
    disconnect-timeout=3s distance=indoors frame-lifetime=0 frequency=5805 \
    frequency-mode=manual-txpower frequency-offset=0 hide-ssid=no \
    ht-ampdu-priorities=0,1,2,3,4,5,6,7 ht-amsdu-limit=8192 \
    ht-amsdu-threshold=8192 ht-basic-mcs=\
    mcs-0,mcs-1,mcs-2,mcs-3,mcs-4,mcs-5,mcs-6,mcs-7 ht-extension-channel=\
    above-control ht-guard-interval=long ht-rxchains=0,1 ht-supported-mcs="mcs-\
    0,mcs-1,mcs-2,mcs-3,mcs-4,mcs-5,mcs-6,mcs-7,mcs-8,mcs-9,mcs-10,mcs-11,mcs-1\
    2,mcs-13,mcs-14,mcs-15" ht-txchains=0,1 hw-fragmentation-threshold=\
    disabled hw-protection-mode=none hw-protection-threshold=0 hw-retries=7 \
    l2mtu=2290 mac-address=00:0C:42:84:5D:5D max-station-count=2007 mode=\
    station-bridge mtu=1500 name=wlan1 noise-floor-threshold=default \
    nv2-cell-radius=30 nv2-noise-floor-offset=default nv2-preshared-key="" \
    nv2-qos=default nv2-queue-count=2 nv2-security=disabled \
    on-fail-retry-time=100ms periodic-calibration=default \
    periodic-calibration-interval=60 preamble-mode=both \
    proprietary-extensions=post-2.9.25 radio-name=SXT-test-Station rate-set=\
    default scan-list=default security-profile=default ssid=SXT-test \
    station-bridge-clone-mac=00:00:00:00:00:00 supported-rates-a/g=\
    6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps,48Mbps,54Mbps tdma-period-size=2 \
    tx-power=2 tx-power-mode=all-rates-fixed update-stats-interval=disabled \
    wds-cost-range=50-150 wds-default-bridge=none wds-default-cost=100 \
    wds-ignore-ssid=no wds-mode=disabled wireless-protocol=any wmm-support=\
    disabled
I'm hoping this is just a simple setting I am missing somewhere. Please let me know if you have any suggestions of where to look for this problem, or if there is any additional information I can provide. Also, if there are any Best Practices I should be following for these types of links, I would appreciate learning about them.

Thanks,
@CC_DKP
 
lazerusrm
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Posts: 162
Joined: Sat Jan 29, 2011 7:56 am

Re: SXT NV2 Extension Channel Problems

Sat May 07, 2011 4:50 am

[Hunch]

Try This:

Enable Extension channel on both devices,

Then disable chain 1 TX/RX on both devices. Test.

Then Enable Chain 1 TX/RX on both devices, and DISABLE Chain 0 TX ONLY on both devices. Test.

[/Hunch]

-Brad
 
CCDKP
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Topic Author
Posts: 170
Joined: Fri Jan 28, 2011 11:24 pm
Location: Midwest, United States

Re: SXT NV2 Extension Channel Problems

Tue May 10, 2011 4:39 pm

[Hunch]

Try This:

Enable Extension channel on both devices,

Then disable chain 1 TX/RX on both devices. Test.

Then Enable Chain 1 TX/RX on both devices, and DISABLE Chain 0 TX ONLY on both devices. Test.

[/Hunch]

-Brad
This weekend I was finally able to get out and run some tests at 350m. The added distance cleared up some minor issues I had with inconsistency at 20MHz width, but no change with the extension channels enabled.

On your advice, I enabled the extension channel and disabled Chain 1, and was surprised to find a stable link at 130Mbps. With just Chain 0 TX disabled, I saw similar speeds, although with slightly more latency (5-10ms as opposed to a very stable 2-6ms before, still well within reason).

Was this the behavior you were expecting to see?

I apologize, but I wasn't able to grab any screenshots of the link statistics. If need be, I can recreate my setup here in the lab and get some proper stats pulled up.

--@CC_DKP
CC_DKP: MTCNA, MTCRE, MTCWE, MTCTCE, part-time packet wrangler
 
CCDKP
Member Candidate
Member Candidate
Topic Author
Posts: 170
Joined: Fri Jan 28, 2011 11:24 pm
Location: Midwest, United States

Re: SXT NV2 Extension Channel Problems

Tue Jun 07, 2011 5:50 pm

It looks like upgrading the radios to 5.4 seems to have fixed my issues. I am easily holding 100Mbit full duplex now, with NV2, both chains enabled, and extension channels turned on.

--@CC_DKP
CC_DKP: MTCNA, MTCRE, MTCWE, MTCTCE, part-time packet wrangler

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