• Steinar H. Gunderson's avatar
    mac80211: support DTPC IE (from Cisco Client eXtensions) · c8d65917
    Steinar H. Gunderson authored
    Linux already supports 802.11h, where the access point can tell the
    client to reduce its transmission power. However, 802.11h is only
    defined for 5 GHz, where the need for this is much smaller than on
    2.4 GHz.
    Cisco has their own solution, called DTPC (Dynamic Transmit Power
    Control). Cisco APs on a controller sometimes but not always send
    802.11h; they always send DTPC, even on 2.4 GHz. This patch adds support
    for parsing and honoring the DTPC IE in addition to the 802.11h
    element (they do not always contain the same limits, so both must
    be honored); the format is not documented, but very simple.
    Tested (on top of wireless.git and on 3.16.1) against a Cisco Aironet
    1142 joined to a Cisco 2504 WLC, by setting various transmit power
    levels for the given access points and observing the results.
    The Wireshark 802.11 dissector agrees with the interpretation of the
    element, except for negative numbers, which seem to never happen
    Signed-off-by: default avatarSteinar H. Gunderson <sgunderson@bigfoot.com>
    Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
mlme.c 132 KB