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Re: What's required to make wireless reliable?

Mark Knecht wrote: 
On Fri, 25 Mar 2005 19:29:27 -0600, Otto Haliburton
<ottohaliburton comcast net> wrote:


-----Original Message-----
From: Mark Knecht [mailto:markknecht gmail com]
Sent: Friday, March 25, 2005 7:01 PM
To: Otto Haliburton
Cc: Getting started with Red Hat Linux
Subject: Re: What's required to make wireless reliable?

On Fri, 25 Mar 2005 18:24:33 -0600, Otto Haliburton
<ottohaliburton comcast net> wrote:


-----Original Message-----
From: Mark Knecht [mailto:markknecht gmail com]
Sent: Friday, March 25, 2005 6:14 PM
To: Otto Haliburton
Cc: Getting started with Red Hat Linux
Subject: Re: What's required to make wireless reliable?


I've moved the router to all the convienient places. It got
significantly better, but not nearly good enough.

Thanks Otto!

Cheers,
Mark


I don't think it has to be metal to work, in fact I am sure it does

not

and

move it vertical also, I mean to a higher location and I also have

heard

that some brands are not as good as others so you might use the old

Frys

15

day money back thing and try a different brand to see if it is

better.


I'm trying to set up my laptop with ndiswrapper so I can run around
the house and do some tests. How do I change the default routes to
stop it from using the eth0 as the default route and make it use
wlan0?

I.e. - currently uses eth0 to get to the gateway and I want it to use
wlan0?

Thanks,
Mark

I think you go to either system or system utilities and there is a

network

device under there and you can change it there. I am currently under xp

and

I can't tell you exactly, but you will see it in the menu and you can

use

its help to see how to use it. Better still just google wlan0 it might

help

better with the problem you are having.



Well I figured out that I can do

ifdown eth0
route del eth0
ifup wlan0
route add default gw Netgear

I can switch to wlan0 and it works. Actually I'm sending this from the
laptop using wireless.

However it's sort of strange but the results from iwlist wlan0 scan
are not valid unless I do ifdown wlan0 ifup wlan0. Unless I do that
the value stays the same no matter where I am in the house.


That is a bit strange.  I have found that the order in which things are
fed to iwconfig is significant.  It may be that the script sets things
in a manner that causes problems.  The
/etc/sysconfig/network-scripts/ifup-wireless script sets up the
wireless stuff in this order:

	mode
	nickname
	network ID (wireless domain)
	frequency/channel (if mode is Ad-hoc)
	sensitivity
	rate
	WEP key
	RTS/CTS
	frag
	ESSID

-13db 12" from the router
-36db here at my desk
-50db in my son's room
-63db in my wife's office
-63db in the kitchen


well, I am surprised that there is that much difference in the values, I
would have expected them to be approximately the same because of the
relative small distance from the router, but you are getting some type of
interference from something in your house.  To me the relative signal
strength should be approximately equal since there should be nothing
interfering with the signal.  If you were outside then it would be a
different situation, cause the signal can ride on electrical wires and other
stuff so it would be stronger in certain areas than others.  What would be
curious if you left your laptop do the processing you were doing in the room
with the router and see if it ever dropped reception.  If you assume that
the router is always putting out a signal at the same level then everything
that is 15 feet from the router should have the same db level then if you
move to 25 feet then those should be the same etc.  in a perfect world, but
obviously something is causing a drop depending on where you are in your
house, unfortunately you don't have the equipment to locate exactly what it
is.  But now that I look at the figures the relative strength in your son,
wife's office and kitchen are actually pretty close and your office is
obviously closer to the router.  Now that I look at it I don't see a
problem, probably something for Rick or a wireless forum to discuss.



-13db 12" from the router
-36db here at my desk
My desk is in the same room as the router but on the other side of the
bed. Approximately 14 feet east of the router.

-50db in my son's room
This machine is 14 feet east and 10 feet south of the router. Go
through 1 wall to get to this machine.

-63db in my wife's office
This machine is approximately 35 feet south of the router. The signal
either goes through 3 walls or goes outside through a window and then
back in through another window to where my wife's desk is.

-73db in the kitchen This is 14 feet east and 55 feet south of the router. The signal most
probably goes through 4 or 5 walls to get here.

Keep in mind that power drop on any signal from a point source drops
as r-cubed. There is nothing between the 12" measurement and the 14
foot measurement.


Uh, isn't that "r squared"?  I can't recall my power calculation stuff.
Decibels (dB) is a logarithmic measurement as well, so things may look
a bit weird.
----------------------------------------------------------------------
- Rick Stevens, Senior Systems Engineer     rstevens vitalstream com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-           "I understand Windows 2000 has a Y2K problem."           -
----------------------------------------------------------------------

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