one way bad: dlink dwl-520, netgear me102

Magnus magnus_k at gmx.de
Mon Jan 20 18:19:23 EST 2003


We use a combination of netgear me102 accesspoint and dlink dwl-520 (11
Mbit, using hostap_pci-driver) in the router to connect a lan to a
dsl-router (suse-linux 8.2, kernelversion 2.4).

The problem is that in one direction (from router to lan) the
transmission is very good, but in the other direction (from lan to
router) the transmission is very worse. The result is that emails with
attachment cannot be sent, filesharing only works in one direction and
no files can be uploaded per ftp to the server (it starts transmitting
but after a while, maybe 500 KB, it stopps). Normal internet works,
downloads ok.

Running iwconfig on router prints:
==================================
wlan0     IEEE 802.11-b  ESSID:"wlan"  Nickname:"uchajewanije"
          Mode:Managed  Frequency:2.472GHz  Access Point:
00:30:AB:22:85:3B
          Bit Rate:11Mb/s   Tx-Power:10 dBm   Sensitivity=1/3
          Retry min limit:8   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality:24/92  Signal level:-86 dBm  Noise level:-100 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:320  Invalid misc:7559   Missed beacon:0
==================================

Running ifconfig on router prints:
==================================
...
wlan0     Link encap:Ethernet  HWaddr 00:40:05:AE:CE:B2
          inet addr:192.168.0.11  Bcast:192.168.0.255
Mask:255.255.255.0
          inet6 addr: fe80::240:5ff:feae:ceb2/10 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2047522 errors:0 dropped:6659 overruns:0 frame:0
          TX packets:2159915 errors:638 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:208447513 (198.7 Mb)  TX bytes:1985993069 (1893.9 Mb)
          Interrupt:9 Memory:c28de000-c28df000
==================================

Why are there 6659 received packets dropped, while on every else
interface 0 are dropped. And also transmitted packets on every else
inface 0 errors occured.

Also pinging a host from the router over the wlan-connection produces
strange output:
==================================
uchajewanije:/etc # ping -s 1000 192.168.0.2
PING 192.168.0.2 (192.168.0.2) from 192.168.0.11 : 1000(1028) bytes of
data.
1008 bytes from 192.168.0.2: icmp_seq=1 ttl=128 time=6.20 ms
1008 bytes from 192.168.0.2: icmp_seq=2 ttl=128 time=5.97 ms
wrong data byte #200 should be 0xc8 but was 0xca
#8      8 9 a b c d e f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20 21 22 23 24 25 26 27
#40     28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 39 3a 3b 3c
3d 3e 3f 40 41 42 43 44 45 46 47
...
#968    c8 c9 ca cb cc cd ce cf d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc
dd de df e0 e1 e2 e3 e4 e5 e6 e7
1008 bytes from 192.168.0.2: icmp_seq=3 ttl=128 time=5.63 ms
==================================

The bigger the packetsize is and the longer you send, the more wrong
data byte errors occure.


We think it is most possible that some parameters are wrong or the
hostap-driver is buggy or our connection is semidirectional bad.

Thank you for reply.
Sincerly, Magnus.





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