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Old 21st October 2013
mickywicky mickywicky is offline
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Question wifi performance (rum)

Hello everyone,

I'm currently using a Belkin USB network adapter on my old OpenBSD server laptop, on a USB 2.0 port:

rum0 at uhub3 port 2 "Belkin Belkin 54g USB Network Adapter" rev 2.00/0.01 addr 3
rum0: MAC/BBP RT2573 (rev 0x2573a), RF RT2528, address XX:XX:XX:XX:XX:XX

it is very stable; the issue is performance... I get ridiculously low transfer speeds, peaking at 150 KB/sec on NFS, Samba or SSH transfers (a quick test with netcat confirms it's the network link).
The same client and server, if using a wired fxp interface over powerlines, yield 4 MB/sec (but that connection drops out when other devices are activated - different story).

OpenBSD and the wireless AP are 5 meters away and have line of sight between them.
Latency between the two is good and consistent (2-4 ms, 0.0% packet loss)
ifconfig rum0:

rum0: flags=28843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST ,NOINET6> mtu 1500
lladdr XX:XX:XX:XX:XX:XX
priority: 4
groups: wlan egress
media: IEEE802.11 autoselect mode 11g (DS1 mode 11g)
status: active
ieee80211: nwid XXXXXX chan 6 bssid XX:XX:XX:XX:XX:XX 119dB wpakey <wpakey> wpaprotos wpa1,wpa2 wpaakms psk wpaciphers tkip,ccmp wpagroupcipher tkip 100dBm
inet 192.168.1.1 netmask 0xffffff00 broadcast 192.168.1.255

Clearly they can hear each other just fine (110+ dB)

The only thing I find odd is: 'DS1 mode 11g' - why would 'media autoselect' settle for the (I'm guessing) slowest setting?
'ifconfig rum0 media' lists a large number of options, from DS1 to OFDM54 (I can paste it here if you want)

I could try and force it to e.g. OFDM54 but I'm wary of losing connectivity as I'm remote to the machine, so I figured I'd ask for opinions or pointers before I try that.
Thank you for reading this post. Any ideas?
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Old 21st October 2013
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jggimi jggimi is offline
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When it comes to dbm status values reported by ifconfig(8), I can never remember if high=good or high=bad. However, the hardware is reporting that it trains at 1Mbps most likely because it cannot communicate with the access point at higher speeds.

Force higher speeds via mediaopt only when you have another way to reach the platform should your change cause a communication break. That means, another network interface, another person, or you at the remote site.
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Old 21st October 2013
mickywicky mickywicky is offline
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High = good, I'm pretty sure about that (typical readings in that building are 70-80 dBm, in other rooms further away from the AP).
So I used an at job 5 minutes in the future to reset the interface if things went wrong, and another to restart the server if that failed, 5 minutes later.
I applied the change remotely to force OFDM54 mode, and it came back after a few seconds.
I cannot actually test right now, but the latency over 1000 is consistently lower than in DS1 mode. Fingers crossed, I'll check it later today and report back.

For reference: ifconfig rum0 media OFDM54 mode 11g

Thanks!
MW
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Old 21st October 2013
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Quote:
So I used an at job 5 minutes in the future...
Wow.... That's absolutely brilliant!

I've never thought of doing that for a test of this type...



...I'm feeling like I've wasted a lot of time over the last several decades, forgetting all about at(1).
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Old 21st October 2013
mickywicky mickywicky is offline
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Glad I could help with the at trick!

So I ran a bandwidth test (netcat) having forced OFDM54... throughput was roughly 4x higher, from 160KB/sec to 600 KB/sec. Good progress!
Then I thought about transmit power... this "server" uses a cardbus extension for USB 2.0, and the card has a power socket. I have nothing I could plug in there, but...

Default settings -> 160 KB/sec
OFDM54 11g -> 600 KB/sec
ifconfig rum0 txpower 15 -> 1.1 MB/sec !!
ifconfig rum0 txpower 5 -> 1.1 MB/sec
ifconfig rum0 txpower 100 -> 1.1 MB/sec

Go figure...

At least I've now got 6x the original throughput, but it's still only 20% of what it can theoretically do and 25% of the 100 MBps wired interface going over power lines.
I'll see if I can find something else, but any other ideas are welcome.
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Old 23rd October 2013
J65nko J65nko is offline
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I have two of these: http://support.netgear.com/product/WNHDE111
One is configured as wireless access point, the other as wireless bridge.

When I scp a file from my OpenBSD firewall (behind the AP) to my PC (Debian stable connected tot he wireless bridge) I get slighty more than 5.0 MB/s:

Code:
753MB   5.1MB/s   02:28
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Old 23rd October 2013
mickywicky mickywicky is offline
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Very interesting... I'd forgotten that these things existed.
I found another USB wifi adapter that uses the uath driver (under a pile of toys...), so I'll benchmark this tonight.
If all else fails, wireless bridges can be quite cheap.

Thanks for the tip!
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Old 23rd October 2013
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J65nko: How far apart are your two wireless devices?
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Old 23rd October 2013
J65nko J65nko is offline
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I just measured the distance: 9.50 meter.

My house has a strange shape. The following ASCII art is an attempt to illustrate it. AP is the access point, and B is the bridge

Code:
|  AP               |
|                   |
|                   |
|                   |
|                   |
|                   |
|                   |
|                   |
|                   |
|                   |
|------ door  ------|
\                    \
 \                    \
  \                    \
   \                    \
    \                    \
     \                    \
      \                    \
       \                    \
        \                    \
         \                    \
          \                    \
           \                    \
            \                    \
             \                    \
              \                    \
               \                  B \
It took me quite a while to figure out the right position. I had to configure both devices in the living room at a distance of about 3 meter. Then I moved the bridge to its final position. While watching the signal strength I played with small variations in direction till I found the one with about 90 - 95% signal strength.
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Old 23rd October 2013
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Thanks for that. mickywicky had mentioned 5m in his case, so I thought a similar comparison would be helpful.

My only other thought is that since you're using 2 identical devices, perhaps inter-manufacturer interoperability is less likely to be an issue.
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Old 24th October 2013
J65nko J65nko is offline
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Besides being from the same manufacturer, these devices also have multiple antennas. And it also helps I am the only user of this wireless link
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Old 25th October 2013
mickywicky mickywicky is offline
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No luck with uath() - got the firmware, the device is recognised but uath0 never appears in the list of interfaces:

uath0 at uhub3 port 1 "Atheros Communications Inc WG111T" rev 2.00/0.01 addr 2
uath0 detached

But never mind for now. 1.1 MB/sec is slow but sufficient, and the link is stable.
Eventually I'll move the OpenBSD box close to the router and go wired again.
Clearly J65nko has higher-end h/w than I do
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