[TriLUG] WLAN Research

Matt Dinsmore matt at centrix.net
Mon May 22 12:15:21 EDT 2006


I would recommend DD-WRT for the firmware if you are gonna go Linksys. 
You will get probably the same performance out the Linksys stuff with 
this firmware as you would with the high-end / pricey Cisco stuff. You 
will find that it is hard to find Linksys routers / access point that 
support 3rd party firmwares though. I believe there is a WRT-54GL or 
something out there now that is specifically designed to run "Linux" as 
it's firmware. I use Buffalo routers at home, which is the new 
recommendation of the DD-WRT guys these days. They are cheap too. I do 
however find the Linksys products seem to have a stronger signal. So you 
would definitely want to amp the Buffalo stuff.

Matt Dinsmore
matt at centrix.net

Greg Brown wrote:
> I've used Ciscos before too, and if money is not an object I would go 
> with
> these units if at all possible (running IOS, not that other OS.. 
> whatever it
> is).
>
> Anyway, if money is an object I would go with WRT54G linksys boxes, NOT
> running Linksys code.  Why?  For distances this great I would highly
> reccomend amplification.  In order to run amps without rediculious 
> noise you
> need to drop the input power on your AP going into the amp.  I've 
> found 20
> mw of power works best.
>
> Being as this is a point-to-point link you can raise the gain on the
> antennas and the amps a bit to.  Here are your limits:
>
> Total    Amp                         Max gain           EIRP in watts
> *30dBm 1W                            6dBi                 3.98
> 29dBm 800mW                      9dBi                 6.35
> 28dBm 630mW                    12dBi                10.14
> 27dBm 500mW                    15dBi                15.81
> 26dBm 398mW                    18dBi                25.23
> 25dBm 316mW                    21dBi                40.28
> 24dBm 250mW                    24dBi                62.79
> 23dBm 200mW                    27dBi                100.2
>
> So, looking at this we have a couple options.  I'd go with Yagi 
> antennas or
> dishes.  Personally I would only mess with 500 mw or 1 watt amps, too 
> much
> freakiness on the adjustable amps.
>
> Use LMR400 antenna cables.  The other stuff has too high loss.  And mount
> the amp as close to the antenna as possible.
>
> Personally I'd go with Antennex Yagis, they are weatherproof and sealed.
> Nice.  At 14.6 dBi gain you can still go with a 500 mw amp and you'll be
> just under max power.  Anything more then 100 yards I'd consider going 
> with
> dishes, but at this power level you should be ok.
>
> Use WPA between the devices too (keep the prying eyes out).  If you get
> adventerous try afterburner mode on the wrts.  I've never tried it, but I
> can't see why not.
>
> Anyway, those are my suggestions.
>
> Greg
>
> *
> On 5/22/06, Matt Dinsmore <matt at centrix.net> wrote:
>>
>> I've done this before, not locally though. We used Cisco 350 bridges.
>> Worked great, except for when it got snowy/icey which I don't think will
>> be a problem here. We had multiple sites with yagi antennas. At the
>> center we had an omni. We had a 3 mile radius. The extreme edges got
>> kinda sketchy, but 100 yards should work fine and be stable.
>>
>> I would recommend the Cisco stuff, or even the Linksys ( which is now
>> owned by Cisco ) stuff if this is tmp / on a budget.
>>
>> How is your line of site ? This is VERY important for long distance 
>> hauls.
>>
>> Matt Dinsmore
>> matt at centrix.net
>>
>> Carl Crider wrote:
>> > I am currently researching parts/designs for a wireless LAN here at my
>> > office.
>> > We need to connect a building that is 100 yards away from our main
>> > switch.
>> > This building houses only 5 PC's. Does anyone have suggestions on both
>> > design and local shops to buy the parts?
>> >
>> > This will be a permanent installation replacing the current 
>> underground
>> > fiber patching these 2 buildings. The fiber has to come up due to
>> > construction.
>> >
>> > Thanks in advance for any input.
>> >
>>
>>
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