atheros (ath) - duplicate packets with long distance link

Johann Hugo jhugo at icomtek.csir.co.za
Mon Nov 24 05:55:26 PST 2003


Hi

I am getting a lot of duplicate packets on my long distance wireless link, but 
on my identical link in the Lab everything works fine. (DWL-AG520 adapter).

The one adapter is configured in hostap mode, and the other one as a
client, both in 11b mode. ( current 5.2-BETA - 24 Nov )

I know there are a lot of CRC errors on the long distance wireless link, but 
if I swap the hostap device with a 802.11b Lucent AP (over the same distance) 
then I don't get any duplicate packets.

atheros# ./athstats
1 beacon miss interrupts
52 tx management frames
106 tx frames discarded prior to association
4 tx failed 'cuz too many retries
88 long on-chip tx retries
45 tx frames with no ack marked
62 tx frames with short preamble
58979 rx failed 'cuz of bad CRC
11 rx failed 'cuz decryption
1511778 rx failed 'cuz of PHY err
    1495162 OFDM timing
    16614 CCK timing
    2 CCK restart
8 periodic calibrations
40 rate control checks
1 rate control dropped xmit rate

AP = DWL-AG520 - HostAP
atheros# ping -s 1450 192.168.10.10
PING 192.168.10.10 (192.168.10.10): 1450 data bytes
1458 bytes from 192.168.10.10: icmp_seq=0 ttl=64 time=27.432 ms
1458 bytes from 192.168.10.10: icmp_seq=0 ttl=64 time=101.903 ms (DUP!)
1458 bytes from 192.168.10.10: icmp_seq=0 ttl=64 time=178.306 ms (DUP!)
1458 bytes from 192.168.10.10: icmp_seq=1 ttl=64 time=15.965 ms
1458 bytes from 192.168.10.10: icmp_seq=1 ttl=64 time=96.968 ms (DUP!)
1458 bytes from 192.168.10.10: icmp_seq=1 ttl=64 time=216.500 ms (DUP!)
1458 bytes from 192.168.10.10: icmp_seq=2 ttl=64 time=27.865 ms
1458 bytes from 192.168.10.10: icmp_seq=2 ttl=64 time=107.189 ms (DUP!)
1458 bytes from 192.168.10.10: icmp_seq=3 ttl=64 time=19.401 ms
1458 bytes from 192.168.10.10: icmp_seq=3 ttl=64 time=138.412 ms (DUP!)
1458 bytes from 192.168.10.10: icmp_seq=3 ttl=64 time=213.613 ms (DUP!)
1458 bytes from 192.168.10.10: icmp_seq=4 ttl=64 time=57.855 ms
1458 bytes from 192.168.10.10: icmp_seq=4 ttl=64 time=134.540 ms (DUP!)

AP = Lucent AP-1000
PING 146.64.86.3 (146.64.86.3): 56 data bytes
64 bytes from 146.64.86.3: icmp_seq=0 ttl=64 time=81.586 ms
64 bytes from 146.64.86.3: icmp_seq=1 ttl=64 time=4.358 ms
64 bytes from 146.64.86.3: icmp_seq=2 ttl=64 time=2.837 ms
64 bytes from 146.64.86.3: icmp_seq=3 ttl=64 time=3.878 ms
64 bytes from 146.64.86.3: icmp_seq=4 ttl=64 time=3.889 ms
64 bytes from 146.64.86.3: icmp_seq=5 ttl=64 time=5.677 ms
64 bytes from 146.64.86.3: icmp_seq=6 ttl=64 time=3.915 ms
64 bytes from 146.64.86.3: icmp_seq=7 ttl=64 time=3.945 ms
64 bytes from 146.64.86.3: icmp_seq=8 ttl=64 time=5.720 ms

Regards
Johann


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