Alix3d2 + Mikrotik R52nM Wifi Access point network performance

[jkusniar]

Hello,

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
athn0: flags=28843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,NOINET6> mtu 1500
        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 192.168.188.1 netmask 0xffffff00 broadcast 192.168.188.255

# cat /etc/hostname.athn0
up media autoselect mediaopt hostap mode 11g chan 11 nwid kusniarovci \
wpakey XXXXXXXX
inet 192.168.188.1 255.255.255.0

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 192.168.188.1 -i 1 -t 60
ap# iperf -s                              
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  4] local 192.168.188.1 port 5001 connected with 192.168.188.32 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

[jkusniar]

Forgot to mention, that disabling pf during iperf tests didn't have any impact on performance.

[J65nko]

IMHO Wireless sucks. Only when a wireless adapter has multiple antenna's it sucks less

The only wireless stuff I use are two standalone Netgear access points of which one is configured as a bridge. The AP is connected to my OpenBSD firewall box (450 Mhz PIII) located in the living room. My computer room is at the other end of the house and separated by a long corridor from the living room. My desktop and servers are connected to a switch that is plugged into the wireless bridge in the corridor.

The AP and bridge have multiple antenna's and the signal strength is around 90%. This results in a connection speed that is workable.

Maybe you could borrow a similar standalone AP and see whether that makes a difference.

My daughter and her boyfriend bought me these two Netgear WNHDE111 units as a birthday present when when we moved into our current house. They have saved from digging, drilling and laying a cable in the garden.

[jkusniar]

Agreed.

Everything, I consider important (my desktop, NAS), runs on gigabit ethernet. The thing is, that there are devices (wife's phone, Kindle ebook reader, wife's netbook), that can't be connected through ethernet. So there is a need for wireless. And since it's there, I'm sometimes lazy to look for a free cable laying somewhere around and connect my work laptop through wireless.

Casual webbrowsing is ok on current setup. But what annoys me, are those slow copy operations of large files, I do from time to time.

I decided to use custom device with open bios and opensource OS, because security is important to me. Anyway, I may borrow some TPlink/netgear, just to compare.