On Friday, February 05, 2016 04:07:22 PM Eric Hillary wrote: > Has anyone experienced that RTS/CTS handshaking stops occurring at the > client if the the access point enables WMM? yes, the 802.11-draftn device has problems (rx and tx become stuck) with 802.11n and proper WMM (and with RTS/CTS). Sadly, I don't know of any workaround that works for all the configurations I tested, other than going for a ath9k_htc device. > Using the carl9170 driver with RTS/CTS handshaking enabled on a USB > Ubiquiti SR71-USB (Atheros AR9170 based wireless adapter). RTS/CTS will > stop working when WMM is enabled on the WAP. You can overwrite carl9170's behavior (per device). You need to have DEBUGFS enabled for the driver (CONFIG_CARL9170_DEBUGFS). There is a control setting in: /sys/kernel/debug/ieee80211/phyX/carl9170/erp 1 - Automatic (default) 2 - Set by mac80211 3 - Force off 4 - Force CTS 5 - Force RTS You can try echo 2 > erp. And check the setting with cat erp > The network is running in 802.11n C-band (5GHz) channels in > Infrastructure mode with an Atheros AR9370 based Access Point. We are > using RTS/CTS handshaking to reduce “Hidden Node” effects. Other > clients in the network require WMM to be enabled. For reasons cited in > http://www.smallnetbuilder.com/wireless/wireless-features/30938-dont- > mess-with-wmm, WMM should be enabled to support 802.11e, > required for 802.11n to use HT (High Throughput) link rates. > > With the WMM turned OFF at the AP and RTS value = 256 at the Ubiquiti > client, the RTS/CTS handshake functions normally. With WMM turned ON at > the AP and RTS value = 256 still on at the client no RTS/CTS handshake > occurs. The carl9170 client stops sending the RTS, and the carl1970 > client ignoring the CTS messages transmitted by the AP, causing > collisions because of my “Hidden Node” condition. > > Had to get scope plots of the RF network traffic between the AP and > client to observe this happening. scope plots from a real analyzer? I would love to have a look at those :). Regards, Christian -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
