Performance drop in Bridge mode without WEP
mike at it-loops.com
Sat Jun 26 13:59:01 EDT 2004
Looking at the WPA issues I have with my setup here, I saw a very
Pentium 200 MMX
Netgear PCI Prism card
WindowsXP / Linux Notebook
The AP is setup to Bridge between the wired and wireless network.
Trying to copy a file between two clients (one on the wired, the other
on the wireless network)
I see the following behaviour.
* Copying a file works in both directions without any problems
* If I copy from the wireless to the wired client the throughput is
* Copying from the AP to the wireless client works too.
* If I copy from the wired to the wireless client I ONLY get around 30
If I start tcpdump br0 on the AP throughput rises again to normal
For testing purposes I configured the notebook to act as AP. Everything
worked without a problem.
I tried the following things:
* Testing different versions of the hostap driver 0.1.x, 0.2.x, CVS
* Installing the same kernel as on the notebook to rule out a kernel or
bridge code problem
So it is either a hardware fault, although I doubt that since the card
is working with WEP enabled, or something is wrong in the hostap_pci
What really looks odd to me is that running tcpdump on the AP speeds up
On a side note I see the following messages in dmesg every time I call
iwconfig on the AP
wlan0 (WE) : Buffer for request SIOCGIWPRIV too small (16<88)
wlan0 (WE) : Buffer for request SIOCGIWPRIV too small (32<88)
wlan0 (WE) : Buffer for request SIOCGIWPRIV too small (64<88)
I know that this normally means that the wireless extensions between
the driver and the tools are not in sync, but I am using the same
versions on the notebook and don't see the messages there.
I am pretty sure that this is not a common problem and I can work
around it (enabling WEP),
but maybe someone has an idea what might be happening here.
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