OpenWrt Forum Archive

Topic: Extreme latencies: WRT54GL (sta) -> WRT54G (ap)

The content of this topic has been archived on 27 Apr 2018. There are no obvious gaps in this topic, but there may still be some posts missing at the end.

Dear,

I'm having some trouble getting two WRT54Gs to communicate WITH acceptable latencies. In fact, setting up the connection itself was a really smooth and went a LOT quicker than I had initially expected (within half an hour from unpacking the box to client mode). Nice job done to those who deserve this!

However these seems to be one lingering issue that should be solved before the solution becomes workable: The latencies (using simple ping) vary wildly between 50 to 600 ms, with over 200 ms average. Interactive traffic becomes (quite) unworkable this way. My setup is described below, including config files.

I have the impression that the "wlan led" on the AP is more busy than on the client. I don't dare to draw conclusions as its different hardware after all.  Could it be that the client is scanning a bit too much or is it just the encryption being done? Or anything else?

Does anyone have pointers or advice how to troubleshoot this problem?

- Joris

==== Access point
Linksys WRT54G v2.2 (216 MHz). Kamikaze 7.07.
Single SSID: "Joris2k", using psk (WPA, not WPA2).
Has been working for ages, no issues whatsoever over the years.

==== Laptop
IBM T60 Laptop with Intel wireless. Latencies are <1ms, but some spikes well below 100ms.
Dell with Intel wireless. Latencies are same as IBM T60.

==== AP Client
Linksys WRT54GL v1.1 (199 MHz). Kamikaze 7.09.
New box, communication works fine.

== Client config:
config wifi-device  wl0
        option type     broadcom
        option channel  3

        # REMOVE THIS LINE TO ENABLE WIFI:
#       option disabled 0

config wifi-iface
        option device   wl0
        option network  lan
        option mode     sta
        option ssid     Joris2k
        option hidden   0
        option encryption       psk
        option key      <Something>

== iwconfig
wl0       IEEE 802.11-DS  ESSID:"Joris2k"
          Mode:Repeater  Frequency:2.422 GHz  Access Point: 00:13:10:92:CE:8E
          Tx-Power:19 dBm
          RTS thr:2347 B   Fragment thr:2346 B
          Encryption key:off
          Link Signal level:-31 dBm  Noise level:-97 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:1  Invalid misc:0   Missed beacon:0

== ps
  PID  Uid     VmSize Stat Command
    1 root        400 S   init
    2 root            SW  [keventd]
    3 root            SWN [ksoftirqd_CPU0]
    4 root            SW  [kswapd]
    5 root            SW  [bdflush]
    6 root            SW  [kupdated]
    8 root            SW  [mtdblockd]
   53 root            SWN [jffs2_gcd_mtd4]
   68 root        412 S   logger -s -p 6 -t
   70 root        404 S   init
   92 root        396 S   syslogd -C16
  101 root        376 S   klogd
  283 root        376 S   crond -c /etc/crontabs
  287 root        416 S   /usr/sbin/dropbear -p 22
  294 root        392 S   httpd -p 80 -h /www -r OpenWrt
  298 root        596 S   /usr/sbin/dropbear -p 22
  299 root        580 S   -ash
  309 root        608 S   /usr/sbin/dropbear -p 22
  310 root        588 S   -ash
  395 root        412 R   ps

Somewhere during the night something has happened to the box (noticed SSH connection was gone). At least now the connection latencies are normal and even more stable than from my laptop. Strange situation...

The discussion might have continued from here.