[FSO/SHR] Strange connection behavior with wifi

ykstortnilats ykstortnilats at yahoo.com.tw
Tue May 19 08:54:00 CEST 2009

I've never noticed this behavior before, everything looks fine until I try to
use linphone for VoIP with wifi connection. The voice quality is really bad
with a lot of latency. I've used linphone with USB network connection and it
works just fine. Then I ping the gateway and find out the following result:
PING ( 56 data bytes

64 bytes from seq=0 ttl=64 time=145.278 ms

64 bytes from seq=1 ttl=64 time=66.024 ms
64 bytes from seq=2 ttl=64 time=80.936 ms
64 bytes from seq=3 ttl=64 time=95.852 ms
64 bytes from seq=4 ttl=64 time=121.809 ms

64 bytes from seq=5 ttl=64 time=42.274 ms
64 bytes from seq=6 ttl=64 time=57.221 ms
64 bytes from seq=7 ttl=64 time=77.001 ms
64 bytes from seq=8 ttl=64 time=96.020 ms
64 bytes from seq=9 ttl=64 time=116.116 ms

64 bytes from seq=10 ttl=64 time=30.772 ms
64 bytes from seq=11 ttl=64 time=52.624 ms
64 bytes from seq=12 ttl=64 time=72.326 ms
64 bytes from seq=13 ttl=64 time=86.816 ms
64 bytes from seq=14 ttl=64 time=99.788 ms
64 bytes from seq=15 ttl=64 time=126.074 ms

64 bytes from seq=16 ttl=64 time=46.254 ms
64 bytes from seq=17 ttl=64 time=56.979 ms
64 bytes from seq=18 ttl=64 time=80.869 ms
64 bytes from seq=19 ttl=64 time=101.196 ms
64 bytes from seq=20 ttl=64 time=116.231 ms

64 bytes from seq=21 ttl=64 time=30.986 ms
64 bytes from seq=22 ttl=64 time=50.692 ms
64 bytes from seq=23 ttl=64 time=77.690 ms
64 bytes from seq=24 ttl=64 time=98.521 ms

I don't know why the time keeps adding up to about 120ms and then drop to
Pinging with different packet size up to 1024 bytes gives pretty much the
same result.
With TCP connections it can be acceptable (I opened up an photo album in
flickr with Dillo and it's pretty fast), but when using audio streaming with
UDP I think this latency makes the voice lags behind.

iwconfig result:
iwconfig eth0
eth0      AR6000 802.11g  ESSID:"NCTU"
          Mode:Managed  Frequency:2.462 GHz  Access Point: 00:11:95:CA:DA:6B
          Bit Rate=54 Mb/s   Tx-Power=15 dBm   Sensitivity=0/3
          Encryption key:off
          Power Management:off
          Link Quality:185/94  Signal level:-166 dBm  Noise level:-96 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:3  Invalid misc:0   Missed beacon:0

The link quality is good. I've also tried to connect FR to my notebook in
ad-hoc mode and the result is similar.

Haven't tried other distributions. I'm using shr-unstable image of May

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