I am trying to understand how WME/WMM works in MadWiFi. What I am interested
in finding out is when and how are different ACs used based on traffic.
through the code, I saw that different hw queues are set up for different
like WME_AC_(BK/BE/VI/VO) and the corresponding parameters for AIFS and
and CWmax are setup properly. In the life cycle of a packet arriving from
ieee80211_hardstart calls ieee80211_classify to calculate the priority level
the AC for the traffic type.
What I found surprising, or rather discomforting is that ieee80211_classify
only VLAN id and/or IP TOS to determine the AC class. Now from what I
from traffic traces and also read on the Internet that IP TOS field is
almost never used.
All voice (Gtalk and Skype) and video streaming traffic data arrives from
with the IP TOS field as 0.
So the big question troubling me is that when (if ever) is data actually
sent using a different
AC class other than the default WME_AC_BE? What am I missing here (assuming
I am not
using VLANs)? Does madwifi never actually use different ACs. Should there be
intelligent classification function or is this the responsibility of the
applications. Is there some
other way by which the applications communicate to the MAC that the data is
I would really appreciate any help in understanding the working of WME
Thanks in advance
On Mon, Jul 28, 2008 at 04:24:57AM -0700, Ashish Sharma wrote:
> Should there
> be a more
> intelligent classification function or is this the responsibility of the
You can set any kind of classification scheme using netfilter/iptables to
set appropriate IP TOS bits.
> Is there some
> other way by which the applications communicate to the MAC that the data
> is high priority?
I don't know, setting IP TOS is estabilished (for example openssh and ftp
servers are using it).
Elen sila lumenn' omentielvo
Ondrej 'SanTiago' Zajicek (email: santiago@...)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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