If the datarate is 6Mbps, and Iperf is trying to send 6Mbps, it is impossible to have no loss, because datarate != throughput. You have ACKs, and maybe some backoff and difs and sifs, etc. So you are going to drop packets, because with the channel configured this way it is not possible to send at 6Mbps (iperf). And dont forget the overhead of the packets, of course.
If you use 12Mbps (datarate) or more, i guess you wont have problems. 2009/9/22 Nick Kossifidis <mickfl...@gmail.com>: > 2009/9/22 Qasim Javed <qas...@gmail.com>: >> Hi, >> >> I have a gentoo system and the latest Ath5k drivers from compat-wireless. I >> downloaded them about a week back. I understand that the tarball is updated >> daily. >> >> I have three Ubiquiti SRC cards (AR5212). I have configured one of them as >> an AP in 802.11a mode using channel 149. The other two are stations >> connected to the AP. I fixed the rate to 6Mbps. >> >> I have an iperf server running on the AP which accepts UDP traffic. One of >> the stations sends UDP packets at a rate of 6Mbps to the AP. Because there >> are no surrounding APs in 802.11a mode, the band is very quiet. However, I >> am surprised that I get 2.6% packet loss when I run the above mentioned >> experiment. The distance of both stations is no more than 10 meters from the >> AP. Also, the txpower for both STAs is 30dbm. >> >> One STA sends UDP packets to the AP at 6Mbps for 30 seconds and the report >> that iperf generates is as follows: >> >> [ ID] Interval Transfer Bandwidth Jitter >> Lost/Total Datagrams >> [ 3] 0.0-30.1 sec 18.3 MBytes 5.11 Mbits/sec 0.301 ms 352/13434 (2.6%) >> >> Considering that there is no activity on this channel except the beacons of >> AP and probe requests/responses from the other STA, how can 352 packets get >> lost? >> >> To make things worse, I tried the above experiment with minimal bandwidth. >> Very oddly, the results are as follows: >> >> [ ID] Interval Transfer Bandwidth Jitter >> Lost/Total Datagrams >> [ 3] 0.0-31.0 sec 44.5 KBytes 11.8 Kbits/sec 0.060 ms 1/ 32 (3.1%) >> >> Why would even a packet get lost at this very slow data rate? I have >> repeated the above several times, and it always results in about the same >> numbers. >> >> Earlier, I had also noticed that if I ping one STA from the other STA, about >> every 10 seconds, the ping response time jumps from 0.8 milliseconds to 25 >> milliseconds. >> >> I would be really grateful if I can get some feedback fro myou guys on this >> so that we can fix whatever is messing things up here. >> >> Thanks, >> -Qasim > > Try reducing tx power and see how it goes... > > > > -- > GPG ID: 0xD21DB2DB > As you read this post global entropy rises. Have Fun ;-) > Nick > _______________________________________________ > ath5k-devel mailing list > ath5k-devel@lists.ath5k.org > https://lists.ath5k.org/mailman/listinfo/ath5k-devel > -- Henrique Marks henriquema...@gmail.com hma...@parks.com.br http://henriquemarks.blogspot.com http://henriquemarks.googlepages.com tel: 30237882 cel: 9838-6869 twitter: henriquemarks _______________________________________________ ath5k-devel mailing list ath5k-devel@lists.ath5k.org https://lists.ath5k.org/mailman/listinfo/ath5k-devel
