sdajacks@hotmail.com hath wroth:
>The router is a Sitecom router and has ports for ethernet connections
>and accepts wireless as well.
Any particular model of Sitecom router? A URL pointing to the
manufacturer web pile would be useful. I'm not familiar with this
beast. Can I assume that you've checked for the latest firmware
updates?
> On the router I have set the following:
>- WEP 128bit encryption
Turn it off during testing. One less headache to deal with.
>- MAC filtering for both wireless network cards
Turn it off during testing. One less headache to deal with.
>- DHCP enabled
>- Firewall enabled but I have put in no settings.
Those are fine. Basically, run the router and wireless at the
defaults.
>The Internet connection is fine from either the desktop or the laptop
>and I can upload/download large files directly through the Internet
>connection.
Yes, but that has nothing to do with wireless to wired file transfers.
The router section and the internet could be dead or disconnected, and
there would be no effect on local LAN file transfers.
>I can also transfer small files (only a few meg) between
>the laptop and desktop that are local on the network. The files I try
>to copy are set as being shared.
You should not have to share specific files. Try sharing a directory
instead for testing. Everything in the directory should be able to be
copied in either direction. If you get a permissions error, work on
getting the Workgroup names identical, or use some other method of
testing (Iperf, see below).
>The problem arises when I try to transfer larger files between the
>laptop and desktop.
The problem arrises when you don't bother to secify how large is a
large file. What size files are you using for testing in megabloats.
Thanks to my recent experiments with DIVX, I consider anything over
the size of a CDROM (about 700MBytes) to be a large file. Your
perception may be different.
>I get an error in Windows
>Explorer saying that the folder location on the PC with the source
>files cannot be found.
That's the result of a wireless disconnect or signal loss. It happens
when the wireless error rate exceeds some secret level and the router
(or client) decides that it's hopeless to continue. It then tries to
re-establish the connection, but usually fails with a lousy signal. If
it succeeds, it often takes so long that your transfer will abort
before it can reconnect. In any case, do something to improve your
wireless signal like drag the laptop closer to the wireless router.
>I check my wireless connection (using the Intel
>wireless pro s/w)
Another missing number. Any particular Intel wireless card? Are you
using Proset 10.5.x ? If not, I suggest you update as 9.x had
problems and 10.1 had a security issue.
<http://www.intel.com/network/connectivity/products/wireless/proset/proset_software.htm>
>I sometimes cannot find my network
>and have to reboot to get it back up and running again.
That could be due to a weak wireless signal, interference from other
wi-fi systems, or problems with firmware in the router or client.
>Are there any tools/techniques that I can use or go through that can
>see why I keep losing the wireless connection only when transfferring
>large files?
Yes. Proset has a page full of signal strength and quality diagnostic
output. It also generates a log page showing the reason for a
disconnect. I don't have a machine with Proset 10.5.x installed
available to determine where it's buried. It's in the menu jumble
somewhere.
For testing, I suggest you do something a bit different using a
diagnostic tool.
Download and install IPerf on both the wired desktop and wireless
laptop.
<http://dast.nlanr.net/Projects/Iperf/>
<http://dast.nlanr.net/Projects/Iperf/iperfdocs_1.7.0.php>
If the desktop is connected via wireless, kindly disable the wireless
and run a CAT5 ethernet cable to the router. The desktop will be used
as the server part of IPerf. Disable any firewall or virus protection
if necessary.
Start with a wired connection from the laptop to the router. In other
words, no wireless and no internet involved. This will test how fast
the machines can run. A 100baseTX-FDX connection should do at least
70Mbits/sec and will often go to just less than 100Mbits/sec.
On the desktop, run:
IPCONFIG
to determine its IP address. Then run:
IPERF -s
to start the server.
On the laptop, run:
IPERF -c ip_address_of_server
You should see a speed result. We can get fancy with options,
bi-directional transfers, errors, and large files later. First, we
check the basic functions and performance.
Now, disconnect the CAT5 cable at the laptop and initiate a wireless
connection. It would be of interest to know the speed at which you
are connected as indicated by Proset. Use the same command line on
the laptop as before:
IPERF -c ip_address_of_server
What do you get for speed? If it's 25Mbits/sec, you're going as fast
as a 54Mbit/sec connection allows. That's considered normal and quite
good. If it's much much much less, you've got a lousy RF connection
or interference and need to do something at the RF level. If you
report your results, please make an effort to not confuse bits and
bytes.
We can also try some other tests:
Find a "large" file and run:
IPERF -c server_ip_address -F filename
In theory, the speed should be about the same with small or large
files. If there is any huge differences, then you'll need a 3rd
computer to determine if it's on the desktop or laptop.
Also, try it in both directions:
IPERF -c server_ip_address -r
I sometimes get large differences with broken ethernet switches and
rotten wiring.
I can't really guess what's causing your problem without numbers. It
could be literally anywhere. However, if there are any issues with
drivers, firmware, signal strength, or interference, this test will
show it.
Hint: Numbers, not descriptions please.
--
Jeff Liebermann
jeffl@comix.santa-cruz.ca.us
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Lose wireless connection only when transferring large files 
Linear Mode
