Return-path: Received: from mail.candelatech.com ([208.74.158.172]:60769 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752495Ab1A2AVL (ORCPT ); Fri, 28 Jan 2011 19:21:11 -0500 Received: from [192.168.100.195] (firewall.candelatech.com [70.89.124.249]) (authenticated bits=0) by ns3.lanforge.com (8.14.2/8.14.2) with ESMTP id p0T0LATR013871 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Fri, 28 Jan 2011 16:21:10 -0800 Message-ID: <4D435D76.2040703@candelatech.com> Date: Fri, 28 Jan 2011 16:21:10 -0800 From: Ben Greear MIME-Version: 1.0 To: linux-wireless@vger.kernel.org Subject: Re: hti->control_chan is 15?? References: <4D4345A8.6060806@candelatech.com> In-Reply-To: <4D4345A8.6060806@candelatech.com> Content-Type: multipart/mixed; boundary="------------000809060708050303080209" Sender: linux-wireless-owner@vger.kernel.org List-ID: This is a multi-part message in MIME format. --------------000809060708050303080209 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 01/28/2011 02:39 PM, Ben Greear wrote: > When testing with 60 stations, 30 against a netgear running HT40 > and 30 against a cheap cisco AP, using HT20, I notice that the > stations on the netgear often choose NO_HT instead of HT40 > for their channel type. > > The root cause appears to be that the hti->control_chan is 15 > in the ieee80211_enable_ht method. > > Everything *should* be running on channel 11. > > Is this just a bug with the AP, or could this be a local > issue? I sniffed on a separate machine (using ath9k NIC), and it agrees that the beacon's control_channel is 14 (I have since set the AP to channel 10 instead of 11, but the control_channel remains 4 higher than expected.) I'm attaching the pkt in pcap format as well. (From wireshark): Vendor Specific: 00:90:4c: HT Additional Capabilities (802.11n D1.00) Tag Number: 221 (Vendor Specific) Tag length: 26 Vendor: 00:90:4c Tag interpretation: 802.11n (Pre) OUI Tag interpretation: HT additional information (802.11n D1.00) Tag interpretation: Control Channel 14 HT Additional Capabilities: 0x000F .... .... .... ..11 = Extension Channel Offset: Extension Channel below control channel (0x0003) .... .... .... .1.. = Recommended Tx Channel Width: Any channel width enabled .... .... .... 1... = Reduced Interframe Spacing (RIFS) Mode: Use of RIFS permitted .... .... ...0 .... = Controlled Access Only: PSMP only .... .... 000. .... = Service Interval Granularity: 5ms (0x0000) HT Additional Capabilities: 0x0008 .... .... .... ..00 = Operating Mode: Pure HT, no protection (0x0000) .... .... .... .0.. = Non Greenfield (GF) devices Present: One or More HT devices are not GF capable HT Additional Capabilities: 0x0000 .... .... .000 0000 = Basic STB Modulation and Coding Scheme (MCS): 0x0000 .... .... 0... .... = Dual Clear To Send (CTS) Protection: Regular use of RTS/CTS .... ...0 .... .... = Secondary Beacon: Primary Beacon .... ..0. .... .... = L-SIG TXOP Protection Support: Not full support .... .0.. .... .... = Phased Coexistence Operation (PCO) Active: PCO is not activated in the BSS .... 0... .... .... = Phased Coexistence Operation (PCO) Phase: Switch to 40MHz phase/keep 40MHz Rx Supported Modulation and Coding Scheme Set (VS): MCS Set Tag interpretation: Rx Modulation and Coding Scheme (One bit per modulation) .... .... .... .... .... .... 0000 0000 = Rx Bitmask Bits 0-7: 0x00000000 .... .... .... .... 0000 0000 .... .... = Rx Bitmask Bits 8-15: 0x00000000 .... .... 0000 0000 .... .... .... .... = Rx Bitmask Bits 16-23: 0x00000000 0000 0000 .... .... .... .... .... .... = Rx Bitmask Bits 24-31: 0x00000000 .... .... .... .... .... .... .... ...0 = Rx Bitmask Bit 32: 0x00000000 .... .... .... .... .... .... .000 000. = Rx Bitmask Bits 33-38: 0x00000000 .... .... ...0 0000 0000 0000 0... .... = Rx Bitmask Bits 39-52: 0x00000000 ...0 0000 0000 0000 0000 0000 000. .... = Rx Bitmask Bits 53-76: 0x00000000 Highest Supported Data Rate: 0x0000 .... .... .... ...0 = Tx Supported MCS Set: Not Defined .... .... .... ..0. = Tx and Rx MCS Set: Equal .... .... .... 00.. = Tx Maximum Number of Spatial Streams Supported: 1 spatial stream (0x0000) .... .... ...0 .... = Unequal Modulation: Not supported HT Information (802.11n D1.10) Tag Number: 61 (HT Information (802.11n D1.10)) Tag length: 22 Primary Channel: 14 HT Information Subset (1 of 3): 0x0F .... ..11 = Secondary channel offset: Secondary channel is below the primary channel (0x03) .... .1.. = Supported channel width: Channel of any width supported .... 1... = Reduced Interframe Spacing (RIFS): Permitted ...0 .... = Power Save Multi-Poll (PSMP) stations only: Association requests are accepted regardless of PSMP capability 000. .... = Shortest service interval: 5 ms (0x00) HT Information Subset (2 of 3): 0x0008 .... .... .... ..00 = Operating mode of BSS: All STAs are - 20/40 MHz HT or in a 20/40 MHz BSS or are 20 MHz HT in a 20 MHz BSS (0x0000) .... .... .... .0.. = Non-greenfield STAs present: All associated STAs are greenfield capable .... .... .... 1... = Transmit burst limit: 2.4 GHz - 6.16 ms | All other bands - 3.08 ms .... .... ...0 .... = OBSS non-HT STAs present: Use of protection for non-HT STAs by overlapping BSSs is not needed 0000 0000 000. .... = Reserved: 0x0000 HT Information Subset (3 of 3): 0x0000 .... .... ..00 0000 = Reserved: 0x0000 .... .... .0.. .... = Dual beacon: No second beacon is transmitted .... .... 0... .... = Dual Clear To Send (CTS) protection: Not required .... ...0 .... .... = Beacon ID: Primary beacon .... ..0. .... .... = L-SIG TXOP Protection Full Support: One or more HT STAs in the BSS do not support L-SIG TXOP protection .... .0.. .... .... = Phased Coexistence Operation (PCO): Inactive .... 0... .... .... = Phased Coexistence Operation (PCO) Phase: Switch to or continue 20 MHz phase 0000 .... .... .... = Reserved: 0x0000 Rx Supported Modulation and Coding Scheme Set: Basic MCS Set Tag interpretation: Rx Modulation and Coding Scheme (One bit per modulation) .... .... .... .... .... .... 0000 0000 = Rx Bitmask Bits 0-7: 0x00000000 .... .... .... .... 0000 0000 .... .... = Rx Bitmask Bits 8-15: 0x00000000 .... .... 0000 0000 .... .... .... .... = Rx Bitmask Bits 16-23: 0x00000000 0000 0000 .... .... .... .... .... .... = Rx Bitmask Bits 24-31: 0x00000000 .... .... .... .... .... .... .... ...0 = Rx Bitmask Bit 32: 0x00000000 .... .... .... .... .... .... .000 000. = Rx Bitmask Bits 33-38: 0x00000000 .... .... ...0 0000 0000 0000 0... .... = Rx Bitmask Bits 39-52: 0x00000000 ...0 0000 0000 0000 0000 0000 000. .... = Rx Bitmask Bits 53-76: 0x00000000 Highest Supported Data Rate: 0x0000 .... .... .... ...0 = Tx Supported MCS Set: Not Defined .... .... .... ..0. = Tx and Rx MCS Set: Equal .... .... .... 00.. = Tx Maximum Number of Spatial Streams Supported: 1 spatial stream (0x0000) .... .... ...0 .... = Unequal Modulation: Not supported > > Thanks, > Ben > -- Ben Greear Candela Technologies Inc http://www.candelatech.com --------------000809060708050303080209 Content-Type: application/octet-stream; name="wifi-n-bad-ctrl-channel.pcap" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="wifi-n-bad-ctrl-channel.pcap" 1MOyoQIABAAAAAAAAAAAAP//AAB/AAAAK1lDTQ/CBQA3AQAANwEAAAAAGgAvSAAAD73NIgAA AAAQApQJoADjAQAAgAAAAP///////zBGmhALmjBGmhALmmB3gP3ZegAAAABkACEEAA1uZXRn ZWFyLTJnLTAxAQiChIuWDBIYJAMBCgUEAQIAACoBADIEMEhgbN0YAFDyAgEBgwADpAAAJ6QA AEJDXgBiMi8A3R4AkEwzzhEb//8AAAAAAAAAAAAAAAAAAAAAAAAAAAAtGs4RG///AAAAAAAA AAAAAAAAAAAAAAAAAAAA3RoAkEw0Dg8IAAAAAAAAAAAAAAAAAAAAAAAAAD0WDg8IAAAAAAAA AAAAAAAAAAAAAAAAAN0JAAN/AQEAAP9/3QoAA38EAQACAEAA3ScAUPIEEEoAARAQRAABAhBH ABAAAAAAAAAQAAAAMEaaEAuaEDwAAQMwhF2t --------------000809060708050303080209--