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[Acx100-devel] [ acx100-Bugs-922326 ] Scanning may miss stations (channel time too short?)
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From: SourceForge.net <no...@so...> - 2004-03-27 15:55:03
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Bugs item #922326, was opened at 2004-03-24 09:57 Message generated for change (Comment added) made by doctormo You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=543745&aid=922326&group_id=75380 Category: None Group: None Status: Open Resolution: None Priority: 7 Submitted By: The Phantom (thephantom1492) Assigned to: Nobody/Anonymous (nobody) Summary: Scanning may miss stations (channel time too short?) Initial Comment: I have a minor but serious problem... My second neighbour also have a wireless network and I'm still in range... The problem is: the driver seems to start a AP scan, and find HIS first! Since reinit isn't working, the card sync to HIS AP and won't let me to switch to mine... My solution is: put a few cds to block the signal of my friend AP so it pick mine instead... Here is all the bugs I got - 0.2.0pre7 and CVS dosen't work on 2.4.25 (unresolved symbols), non-pre worked fine, but worked fine on 2.6.4 - eject the card ooups the kernel - can't change anything: once initialised don't touch or bye bye connection - slower than in xp (under 50% of xp speed) ---------------------------------------------------------------------- Comment By: Martin Owens (doctormo) Date: 2004-03-27 15:55 Message: Logged In: YES user_id=619936 One man show eh, call me. ---------------------------------------------------------------------- Comment By: The Phantom (thephantom1492) Date: 2004-03-26 05:31 Message: Logged In: YES user_id=1005247 beacon at 100ms seems to have solved the trouble... so I see that the scan code is ok for defaults settings, but isn't for anything else... so what I see is: the scan code could be revised to extend the scan length, but isn't a priority... let's put it on a todo list... notice the beacon can be anywhere between 1ms and 1000ms... your code seems to work fine for 100ms, but at 200 it already have trouble... XP scan take about 1 sec, so I guess your should be the same... ---------------------------------------------------------------------- Comment By: The Phantom (thephantom1492) Date: 2004-03-26 04:51 Message: Logged In: YES user_id=1005247 beacon interval: 200ms I'll try other values ---------------------------------------------------------------------- Comment By: Andreas Mohr (andim2) Date: 2004-03-26 00:49 Message: Logged In: YES user_id=132674 That's what I suspected which might be a problem if having two APs on one channel is actually supposed to work (and since it doesn't work either when you use differing channels, it's clearly a driver config issue if it doesn't work). Question: what config is your beacon interval setup on your AP? and could you try to figure out the beacon interval of the neighbour's AP? (count beacon logs per log second). Probably your AP has very low beacon activity, so we are too fast and miss the next beacon when switching to the next channel... I'll have a look at our scan timing values, they seem to be problematic. I'll also add an iwpriv to adjust them. ---------------------------------------------------------------------- Comment By: The Phantom (thephantom1492) Date: 2004-03-26 00:16 Message: Logged In: YES user_id=1005247 other testing... I'm actually in the kitchen, where the other AP isn't accessible test is: /etc/init.d/net.wlan0 stop; rmmod acx_pci; modpribe acx_pci; /etc/init.d/net.wlan0 start I did that several time in a row... the net.wlan0 is the gentoo net script that I added the iwconfig line there the result is: work one time on 2-3... when it work, it work when it don<t work, it can't detect the AP o.O so I guess the scan code is buggy... maybe it dosen't take enought time to scan? ---------------------------------------------------------------------- Comment By: The Phantom (thephantom1492) Date: 2004-03-25 23:54 Message: Logged In: YES user_id=1005247 even if I set my AP to a different channel the same thing happend... in fact, I tried channel 11 and channel 1, same result... I'm back on channel 6 because the AP came back to it somehow... (I guess I hit the channel list by accident)... anyway, when I opened this bug I was on channel 11... on XP it work flawlessy, I get a list of detected AP and I can choose mine or the other... I just changed it again to channel 1 and same thing.... set channel 1, do a scan, detect AP channel 6, join that AP... I put a pile of cd, set chan1, do a scan, detect AP chan1, join my AP... I didn't inclued the dmesg, as I think it's pointless since it's the same message, except change 6 to 1... and no, it's not a PEBKAC case.... any channel I set my AP do the same thing! as I said, windows deal flawlessy with conflicting channel as you said... hence why I see it as a driver bug... so... - my ap is channel 1, essid 4565 - other ap is channel 6 essid default - scan only see ap chan 6 unless I block that signal with cds - scan see chan6 even if set to chan1, and select the AP chan6! - WinXP handle the 2 AP on same channel, see both and allow to choose between both and work flawlessy - Once I block the other AP signal, I get the link and work well I'm suspecting a bug in the scan code... as it should list both and only list one... ---------------------------------------------------------------------- Comment By: Andreas Mohr (andim2) Date: 2004-03-25 10:42 Message: Logged In: YES user_id=132674 I hereby give you official authorization to carry a "PEBKAC" sign in front of you. :-) (to find out what PEBKAC means is left as an exercise to the reader) If you have two stations on the same channel (channel 6, to be exact, as the log indicates), then of course there may be horrible interference to be expected. While the protocol may have some kind of protection against that, environmental conditions may easily lead to disruption - multipath signal delays etc. pp. OK, maybe the driver actually SHOULD be able to always properly receive scans of several stations in one channel (I'm not sure here). Does wireless operation actually work with other cards/setups given conflicting APs? I strongly doubt it, but maybe that's the case and maybe I'm wrong and our driver really should be able to do something about it... Hmm, or does that mean the XP driver properly finds both stations on channel 6? (that could perhaps be because the XP driver may be rescanning several times and growing the list of APs found...) ---------------------------------------------------------------------- Comment By: The Phantom (thephantom1492) Date: 2004-03-25 09:49 Message: Logged In: YES user_id=1005247 ok, problem is back and I have dmesg logs :/ I'll paste here the most important part and attach the complete output ======== wrong AP ======== acx100_process_probe_response: found and registered station 0: ESSID "default" on channel 6, BSSID 00 80 C8 23 61 BD, Access Point/22Mbps, Caps 0x0041, SIR 29, SNR 0. Radio scan found 1 stations in this area. <Scan Table> 0: SSID="default",CH=6,SIR=29,SNR=0 peer_cap 0x41, needed_cap 0x01 ESSID doesn't match: "default" (station), "4565" (config) now I block the signal with cds ======== good ap, less than 4 feet away ======== acx100_process_probe_response: found and registered station 0: ESSID "4565" on channel 6, BSSID 00 40 05 55 19 93, Access Point/22Mbps, Caps 0x0041, SIR 90, SNR 0. Radio scan found 1 stations in this area. also, I get... Tx error occurred (error 0x20)!! (maybe distance too high? - change 'iwconfig txpower XXX') iwconfig call is: iwconfig wlan0 essid 4565 channel 6 mode managed ---------------------------------------------------------------------- Comment By: The Phantom (thephantom1492) Date: 2004-03-25 00:25 Message: Logged In: YES user_id=1005247 aw, what a bad report I did... that's what happend when you write things at 6am (before you go to sleep, not when you wake up) anyway My setup: - DLink DI-614+ (wireless router, 802.11b+, 22mbps) - channel 1/6/11 (currently 11, all do the same thing) - essid changed to "4565" - WAP disabled (couln't make it work under linux) - DLink DWL-650+ - Running under Gentoo - kernel 2.6.4 / 2.4.25 other AP should be a SMC something (I have no confirmation yet that it's his, but I beleive so..) on channel 6 with ESSID: default what seems to happend is: the card do a scan, find his AP, then connect to his, then the driver try to change the parameters... and that's where the problem begin... then it lost the signal I'll try to reproduce it and I'll post the dmesg result right now I seems to be unable to get my friend's AP signal (disabled my AP, don't get any signal now... that's what happend when you are on the border line...) yes, xp use 4X, if I get time and if I'm bored then I'll reput XP on my lappy (6 gig isn't enought for 2 os) and I'll do benchmarking (idea on how to do it the best is always welcome, as I beleive copying files isn't the best way, but should be good enought) another post is comming asap with better log... ---------------------------------------------------------------------- Comment By: Andreas Mohr (andim2) Date: 2004-03-24 10:14 Message: Logged In: YES user_id=132674 Please provide a more detailed description. I don't have any setup information from you, I don't have any information about his AP, and no logs provided. My crystal ball is broken today ;-) I'd actually go as far as saying that if you had done a proper log analysis you'd have known why it picked his and not yours... (such as having specified the wrong ESSID or so...) Is that really pre7 or a plus_fixes version of it? And what does non-pre mean? We've been using pre quite long now... - card eject may still oops the kernel in case of running traffic (proper hardware management is difficult) - I have to do more tests about that one - we probably sometimes don't act the way we're supposed to on parameter change... - hmm, is that with 4X mode enabled in XP or not? if it's much slower with 22Mbps or 11Mbps STANDARD mode in Linux than in XP, then I should try to debug it I don't have any reference numbers here unfortunately, since I NEVER EVER use XP... Sorry for these problems, it's almost a one man show currently, and a wireless driver is not exactly child's play :- ---------------------------------------------------------------------- Comment By: The Phantom (thephantom1492) Date: 2004-03-24 09:59 Message: Logged In: YES user_id=1005247 I forgot, I was unable to set an encription key, lost the connection (it then say something like out of range, can't find AP....) ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=543745&aid=922326&group_id=75380 |