[PLUG] Wireless network card

Keith Lofstrom keithl at kl-ic.com
Fri Oct 31 12:11:02 UTC 2003


On Thu, 2003-10-30 at 22:56, Keith Lofstrom wrote:
> Note also that you probably do NOT want to put a PCI wireless card into
> a typical desktop.

Derek Loree wrote:
> The PCI wireless cards themselves are fine, its the antennae that they
> come with that suck so bad.  At least get a 3 or 4 foot cable with a
> desk mount antenna.

Good point - but the antennae are a bit harder to find.  Also, note that
there will be significant cable losses if you try to go more than a few
feet, or aren't using top-quality cable.  

I found it easier to just perch a WAP on a high shelf, and run ethernet
and power up to it.  Antenna placement can be nasty.


Derek Loree wrote:
> I haven't tried to build a wireless network with only external WAP's,
> how is that done?  Ad-hoc (or peer-to-peer) mode?

No, regular old managed mode, with the WAP serving DHCP and so forth.
I suppose there could be problems with handoff - I only have one WAP,
so I haven't worked that out yet.  You will have the same problem with
PCI/Linux-box wireless systems;  you will need to make the systems hand
off connection information one to another.  It can be done.


Derek Loree wrote:
> I've had lots of problems with the off the shelf WAP's, a lot more than
> when running a PC based linux firewall/AP with a PCI card.  It is
> infinitely more configurable, and much more user friendly to have your
> connection inside your box.

Sometimes infinite configurability is NOT a feature :-).  But that
wouldn't be us, would it?  :-) :-)

The problem with most wireless cards is that many do not have Linux
drivers, and the manufacturers have a tendency to change chipsets and
keep the same model number.  I'd guess that 60% of the hardware on the
shelf at Fry's doesn't have Linux drivers.  If you do a LOT of research
before buying, you can probably reliably buy a card with a supported
chipset.

On the other hand, if you get a web-configurable WAP, you may not get
all the configurability you would like, and you might not be able to
coordinate a mesh of WAPs, but you are almost guaranteed compatability,
because web browsers are mostly OS agnostic.  And you can usually find
out about web-configurability from the product box.

Case in point - I purchased a Siemens PCMCIA card for my laptop, and
a Siemens WAP, real cheap from Frys.  Well, the PCMCIA card uses the
TI chipset (on the wlan website, it says PRISM2) and while there is 
a Linux driver development program going on, it is nowhere near ready
for prime time.  The WAP, on the other hand, was up and running in about
30 minutes with DHCP, 128 bit WEP, and similar goodies.  Granted, I was
*not* able to do things like force a fixed address for the laptop, and
the WAP wants to be its own little firewall, but I can live with such
annoyances.

When I go for configurability, I will either use an old laptop as an
access point, or I will go for a Soekris box.  Either way, I can 
move the box right up next to the antenna, and I will be using a
PCMCIA card.  Given that the PCMCIA cards are cheaper (higher volume,
and the PCI cards are often a PCMCIA card mounted in a box on a PC
board) and more versatile, and don't need extra cabling to get to
a decent antenna mount point, this is probably a better way to go.

BTW, I hope to take one of my old TP560 laptops and put a couple of
PRISM2 PCMCIA cards in it, make it into a WAP/repeater, and broadcast
"Radio Free Linux" from my attic.  Since my comcast TOS does not permit
me to broadcast internet access, I will probably just serve up local
content - a dozen or so downloadable Linux distros.

Keith

-- 
Keith Lofstrom           keithl at ieee.org         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs




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