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Old 12th January 2015
jkusniar jkusniar is offline
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Join Date: Jan 2015
Posts: 3
Default Alix3d2 + Mikrotik R52nM Wifi Access point network performance


I've assembled small AP using this hardware:
  • alix 3d2 computer board with 500 MHz AMD Geode LX800 and 256 MB RAM
  • Mikrotik R52nM mini PCI wireless adapter (athn)
    athn0 at pci0 dev 12 function 0 "Atheros AR9280" rev 0x01: irq 9
    athn0: AR9280 rev 2 (2T2R), ROM rev 21, address 4c:5e:0c:11:c3:5f

After smooth OS installation (5.6 stable) to CF card and simple AP setup using only FAQ and manpages I got it up and running:

# ifconfig athn0
        lladdr 4c:5e:0c:11:c3:5f
        priority: 4
        groups: wlan
        media: IEEE802.11 autoselect mode 11g hostap
        status: active
        ieee80211: nwid kusniarovci chan 11 bssid 4c:5e:0c:11:c3:5f wpakey XXXXXXXXXXX wpaprotos wpa1,wpa2 wpaakms psk wpaciphers tkip,ccmp wpagroupcipher tkip
        inet netmask 0xffffff00 broadcast

# cat /etc/hostname.athn0
up media autoselect mediaopt hostap mode 11g chan 11 nwid kusniarovci \
Everything's default, just pf (nat), dhcpd... running nicely except for wireless throughput. Noticable when copying large files over local network. I tried to measue performace using iperf from linux laptop client to the AP:

linux_client$ iperf -c -i 1 -t 60
ap# iperf -s                              
Server listening on TCP port 5001
TCP window size: 16.0 KByte (default)
[  4] local port 5001 connected with port 48367
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-60.2 sec   111 MBytes  15.5 Mbits/sec
Linux client (T430 with intel centrino wireless adapter) reports wifi is running in 54Mbit mode:

wlp3s0    IEEE 802.11abgn  ESSID:"kusniarovci"  
          Mode:Managed  Frequency:2.462 GHz  Access Point: 4C:5E:0C:11:C3:5F   
          Bit Rate=54 Mb/s   Tx-Power=15 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=70/70  Signal level=-14 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:168   Missed beacon:0
Computers are next to each other.
  • Are measurements using iperf correct?
  • What are possible tuning "knobs" to get better throughput? (I found nice post on network performance using some sysctl tweaks, but didn't experiment yet)
  • Have I reached hardware limits? Hope not, got simillar performance using raspberry Pi+debian+noname USB wifi dongle
Thanks for any pointers
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