Re: Forwarded mail....
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This sounds like his laptops wifi card has renegotiated its over the
air speed to lower then 11Mbps. In real world scenarios 802.11b
networks usually can only push 3-4M sustained sometimes 5M and this is
while at a over the air negotiated speed of 11Mbps.
Additionally, based on the settings for the wireless AP will also
determine what speeds your wireless card can renegotiate to when it has
weak signal or path issues. In my Linksys AP by default it is set to
only allow the speeds of "1-2MBps" as Basic Rates and has rates of
"1-2-5.5-11MBps" for Transmit Rates. Additionally any UDP testing you
do over wireless will be limited by the UDP performance of the AP
before any other components UDP performance limit is reached.
There is an extensive test database at www.practicallynetworked.com
however the site has gotten a bit crowded over the past year but they
do list max throughput tests for APs and WiFi NICs in controlled
conditions.
Daniel E. Spisak
Editorial Associate
Byte Media Lab
www.byte.com
562-331-1603
On Feb 16, 2004, at 3:28 PM, Kevin Gibbs wrote:
> Anyone using WiFi?
>
> Kevin
>
> ---------- Forwarded message ----------
> Date: Tue, 10 Feb 2004 16:25:17 -0800
> From: Amoolya <amoolya --at-- athenasemi.com>
> To: kgibbs --at-- ncsa.uiuc.edu
>
> hi,
>
> I am new to iperf and using iperf 1.7 on windows 2000/XP. It works
> fine with
> the bandwidth specified on the ethernet network. But the problem
> starts when
> I run it in the 802.11b environment. I am trying to tet the bandwidth
> for
> the wireless nic. When I run the following command on the server :
>
> iperf -s <host> -u -n 2048K -b 30M -w 4M
>
> I get the proper output with almost no loss and bandwidth upto 29.9Mbps
>
> But when i run the similar thing on the laptop :
>
> iperf -c <server> -u -n 2048K -b 30M -w 4M
> the results are fluctuate wildly. Sometimes the bandwidth goes till 24
> - 25
> Mbps (when it manages to send all the packets) but most of the time it
> just
> send about 160-190 packets and stops with a bandwidth of 5 or 9Mbps.
> with an
> error saying "write failed" Interrupted function call.
>
> My question is there something I am not understanding about udp
> behaviour or
> is it the driver problem.
>
> Any help will be really appreciated. Also let me know if there is some
> other
> tool i can use for what i am trying to do.
>
> thanks
> Amoolya
>
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