Return-path: Received: from mail-bw0-f227.google.com ([209.85.218.227]:51546 "EHLO mail-bw0-f227.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753179AbZKIKji (ORCPT ); Mon, 9 Nov 2009 05:39:38 -0500 Received: by bwz27 with SMTP id 27so3278658bwz.21 for ; Mon, 09 Nov 2009 02:39:43 -0800 (PST) Date: Mon, 09 Nov 2009 11:39:16 +0100 Message-ID: From: Holger Schurig To: linux-wireless Subject: erraneous connect with short-slot-time fails MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi ! Background: ath5k-based card, wireless-testing v2.6.32-rc6-41576-g4408b3b, wpa_supplicant hostap_0_6_7-581-geb999fe I just got disconnected all the time to some AP and I wondered what the issue was. That's the output from "iw event:" wlan0 (phy #4): auth 00:1b:d4:44:35:90 -> 00:15:e9:84:1a:54 status: 0: Successful wlan0 (phy #4): assoc 00:1b:d4:44:35:90 -> 00:15:e9:84:1a:54 status: 25: Association request rejected due to requesting station not supporting the short slot time option wlan0 (phy #4): failed to connect to 00:1b:d4:44:35:90, status: 25: Association request rejected due to requesting station not supporting the short slot time option First thing: the error message is confused. I turned off short-slot-time on the AP, so it's the AP that does not support it. However, the real question remains: why does the station (ath5k+mac80211) tries to use short-slot-time in the first place? In the probe response, the AP says clearly that he doesn't support this. Here's the (partial) assoc request, followed by a (partial) assoc response. And to shed evidence on the turned-off-status of the AP, at the end is also a probe response from the AP: IEEE 802.11 Type/Subtype: Association Request (0) Frame Control: 0x0000 (Normal) Version: 0 Type: Management frame (0) Subtype: 0 Flags: 0x0 DS status: Not leaving DS or network is operating in AD-HOC mode (To DS: 0 From DS: 0) (0x00) .... .0.. = More Fragments: This is the last fragment .... 0... = Retry: Frame is not being retransmitted ...0 .... = PWR MGT: STA will stay up ..0. .... = More Data: No data buffered .0.. .... = Protected flag: Data is not protected 0... .... = Order flag: Not strictly ordered Duration: 314 Destination address: 00:1b:d4:44:35:90 (00:1b:d4:44:35:90) Source address: 00:15:e9:84:1a:54 (00:15:e9:84:1a:54) BSS Id: 00:1b:d4:44:35:90 (00:1b:d4:44:35:90) Fragment number: 0 Sequence number: 15 IEEE 802.11 wireless LAN management frame Fixed parameters (4 bytes) Capability Information: 0x0431 .... .... .... ...1 = ESS capabilities: Transmitter is an AP .... .... .... ..0. = IBSS status: Transmitter belongs to a BSS .... ..0. .... 00.. = CFP participation capabilities: No point coordinator at AP (0x0000) .... .... ...1 .... = Privacy: AP/STA can support WEP .... .... ..1. .... = Short Preamble: Short preamble allowed .... .... .0.. .... = PBCC: PBCC modulation not allowed .... .... 0... .... = Channel Agility: Channel agility not in use .... ...0 .... .... = Spectrum Management: dot11SpectrumManagementRequired FALSE .... .1.. .... .... = Short Slot Time: Short slot time in use .... 0... .... .... = Automatic Power Save Delivery: apsd not implemented ..0. .... .... .... = DSSS-OFDM: DSSS-OFDM modulation not allowed .0.. .... .... .... = Delayed Block Ack: delayed block ack not implented 0... .... .... .... = Immediate Block Ack: immediate block ack not implented Listen Interval: 0x0001 ... CONCLUSION: mac80211 tries to use short-slot time. IEEE 802.11 Type/Subtype: Association Response (1) Frame Control: 0x0010 (Normal) Version: 0 Type: Management frame (0) Subtype: 1 Flags: 0x0 DS status: Not leaving DS or network is operating in AD-HOC mode (To DS: 0 From DS: 0) (0x00) .... .0.. = More Fragments: This is the last fragment .... 0... = Retry: Frame is not being retransmitted ...0 .... = PWR MGT: STA will stay up ..0. .... = More Data: No data buffered .0.. .... = Protected flag: Data is not protected 0... .... = Order flag: Not strictly ordered Duration: 314 Destination address: 00:15:e9:84:1a:54 (00:15:e9:84:1a:54) Source address: 00:1b:d4:44:35:90 (00:1b:d4:44:35:90) BSS Id: 00:1b:d4:44:35:90 (00:1b:d4:44:35:90) Fragment number: 0 Sequence number: 1014 IEEE 802.11 wireless LAN management frame Fixed parameters (6 bytes) Capability Information: 0x0000 .... .... .... ...0 = ESS capabilities: Transmitter is a STA .... .... .... ..0. = IBSS status: Transmitter belongs to a BSS .... ..0. .... 00.. = CFP participation capabilities: Station is not CF-Pollable (0x0000) .... .... ...0 .... = Privacy: AP/STA cannot support WEP .... .... ..0. .... = Short Preamble: Short preamble not allowed .... .... .0.. .... = PBCC: PBCC modulation not allowed .... .... 0... .... = Channel Agility: Channel agility not in use .... ...0 .... .... = Spectrum Management: dot11SpectrumManagementRequired FALSE .... .0.. .... .... = Short Slot Time: Short slot time not in use .... 0... .... .... = Automatic Power Save Delivery: apsd not implemented ..0. .... .... .... = DSSS-OFDM: DSSS-OFDM modulation not allowed .0.. .... .... .... = Delayed Block Ack: delayed block ack not implented 0... .... .... .... = Immediate Block Ack: immediate block ack not implented Status code: Association denied due to requesting station not supporting short slot operation (0x0019) Association ID: 0x0000 Tagged parameters (0 bytes) ... CONCLUSION: the AP doesn't like that. And the textual representation from tshark for this error as also confused about the roles of AP and station :-) IEEE 802.11 Type/Subtype: Probe Response (5) Frame Control: 0x0050 (Normal) Version: 0 Type: Management frame (0) Subtype: 5 Flags: 0x0 DS status: Not leaving DS or network is operating in AD-HOC mode (To DS: 0 From DS: 0) (0x00) .... .0.. = More Fragments: This is the last fragment .... 0... = Retry: Frame is not being retransmitted ...0 .... = PWR MGT: STA will stay up ..0. .... = More Data: No data buffered .0.. .... = Protected flag: Data is not protected 0... .... = Order flag: Not strictly ordered Duration: 314 Destination address: 00:20:a6:a0:56:1b (00:20:a6:a0:56:1b) Source address: 00:1b:d4:44:35:90 (00:1b:d4:44:35:90) BSS Id: 00:1b:d4:44:35:90 (00:1b:d4:44:35:90) Fragment number: 0 Sequence number: 1845 IEEE 802.11 wireless LAN management frame Fixed parameters (12 bytes) Timestamp: 0x0000004DA3BDE1FA Beacon Interval: 0.102400 [Seconds] Capability Information: 0x0011 .... .... .... ...1 = ESS capabilities: Transmitter is an AP .... .... .... ..0. = IBSS status: Transmitter belongs to a BSS .... ..0. .... 00.. = CFP participation capabilities: No point coordinator at AP (0x0000) .... .... ...1 .... = Privacy: AP/STA can support WEP .... .... ..0. .... = Short Preamble: Short preamble not allowed .... .... .0.. .... = PBCC: PBCC modulation not allowed .... .... 0... .... = Channel Agility: Channel agility not in use .... ...0 .... .... = Spectrum Management: dot11SpectrumManagementRequired FALSE .... .0.. .... .... = Short Slot Time: Short slot time not in use .... 0... .... .... = Automatic Power Save Delivery: apsd not implemented ..0. .... .... .... = DSSS-OFDM: DSSS-OFDM modulation not allowed .0.. .... .... .... = Delayed Block Ack: delayed block ack not implented 0... .... .... .... = Immediate Block Ack: immediate block ack not implented ... Who's the culprit, mac80211 or wpa_supplicant? -- http://www.holgerschurig.de