Jon, this is an interesting observation. We might have a problem on the rx handling of short preambles. I believe tx should be fine, because it is pretty straight forward. This is something we have to look into.
Kind regards, Uli Am 29.12.2006 um 00:11 schrieb Jon Smirl: > On 12/28/06, Daniel Drake <[EMAIL PROTECTED]> wrote: >> Jon Smirl wrote: >> > First thing I need to figure out is why I can't finish a 250MB copy >> > over pure 802.11g without dropping the connection. I am getting >> > hundreds of these in the logs: >> > kernel: usb 5-1.3: handle_retry_failed_int() retry failed interrupt >> >> This interrupt occurs when the device failed to transmit a unicast >> frame. It retries several times (and gives us an interrupt for each >> retry) and then sends a final interrupt saying that it's given up. >> The >> definition of "failed to transmit" is "did not receive an ACK >> within a >> predefined timeframe". >> >> It has nothing to do with software or protocol retry. Lowering the >> rate >> would be a sensible experiment. > > If the 802.11 MAC fails to transmit the frame or signals an error > because of a missing MAC level ack, then TCP will do the retry at > layer 4. That's part of the sliding window code in the TCP/IP > protocol. Retries at the TCP layer can be pretty slow. > > I tried all rates from 18M to 54M and couldn't get a 250MB copy > without dropping the link. That was with the router set to 802.11g > only. If I turn on 802.11bg the copy works every time. Dropping the > link means that there were so many retries that TCP closed the socket > and caused the layer 7 SMB copy to fail. > > So why am I dropping so many packets with the router at 802.11g and > not with the router at 802.11bg? I'll record a session with Ethereal > and see if it gives me any clues. > > I just noticed my Nokia 770 sitting on my desk in sleep mode. It may > be waking up and causing interference I'll turn it off and do some > more experiments. Nokia 770 is 802.11bg so it's not likely causing > problems. > >> > The nodes in my test are 5ft apart with 100% strength, 99% >> quality at >> > 54M on a clear channel. I would hope that they can exchange packets >> > without dropping them. >> >> Pay little attention to the strength/quality values, they are very >> fictitious. >> >> Daniel >> > > > -- > Jon Smirl > [EMAIL PROTECTED] -- Uli Kunitz ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Zd1211-devs mailing list - http://zd1211.ath.cx/ Unsubscribe: https://lists.sourceforge.net/lists/listinfo/zd1211-devs
