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Date:      Mon, 24 Nov 2003 12:07:28 -0500
From:      Barney Wolff <barney@databus.com>
To:        Johann Hugo <jhugo@icomtek.csir.co.za>
Cc:        current@freebsd.org
Subject:   Re: atheros (ath) - duplicate packets with long distance link
Message-ID:  <20031124170728.GA36748@pit.databus.com>
In-Reply-To: <200311241555.13381.jhugo@icomtek.csir.co.za>
References:  <bk7c8o$rdo$1@sea.gmane.org> <344312645.1063725379@melange.errno.com> <200311112352.02252.jhugo@icomtek.csir.co.za> <200311241555.13381.jhugo@icomtek.csir.co.za>

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Off-the-wall suggestion:  run tcpdump -e and check whether both responses
are coming from the same host.  Unless you're running WEP, you many have
an unexpected guest.  (WEP is no guarantee, but it's better than nothing.)

On Mon, Nov 24, 2003 at 03:55:13PM +0200, Johann Hugo wrote:
> 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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-- 
Barney Wolff         http://www.databus.com/bwresume.pdf
I'm available by contract or FT, in the NYC metro area or via the 'Net.



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