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From: Bill Kearney on 24 Apr 2008 07:32
> Thanks for prompt reply... It looks like I've found some real experts.
>
> The area I'm trying to cover is the top floor of an apartment house
> occupied by ten friends and potentially ten lap top computers. The
> building is 100 feet from front to back and 30 feet wide.

> The building is in an area with lots and lots of students, many of who
> have their own wireless access points.

You're screwed. Trying to curb the amount of interference from all the
poorly configured routers will be like herding cats.

Unlicensed wireless can lead to just what you've encountered, a conflicting
mess.

> Currently, there is one wireless router located in the center of the top
> floor; it is set for maximum power on the least used channel.

For that small an area max power is probably not needed, nor desired.

Although the current router and others that we have tried claim
> to deliver range to 100 feet, reception beyond 30 feet is marginal (one
> bar) to useless, especially at night when many others seem to power up
> their computers and wireless equipment. A directional antenna advertised
> as providing 10 db of gain did not seem to help significantly independent
> of its positioning. (It was a pole antenna that supposedly achieved its
> gain by flattening the radiation pattern.) It seems to be possible to get
> reception through two walls, but any more that that and reception is
> unacceptable. Each user wants to be able to connect from his/her desk and
> not relocate to the kitchen counter because of its closer position to the
> central source.

Some construction materials will block enough of the signal to prevent
decent reception. Older buildings usually, but new buildings with metal
stud walls can also be problematic. The only solution, really, is to use
more access points at lower power.

> I'm aware that the you can change the IP address ranges on most all
> routers, but having units whose default states don't conflict makes
> network repair easier; it is one less thing to have to reset when
> something goes wrong.

Again, you're making a choice based on a less-than-smart plan. If you want
reset programmability then get a router that can have a 3rd party firmware
loaded. Configure that firmware ahead of time to your desired setup (by
recompiling the firmware) and load that on each. Frankly, that's a lot more
trouble than it's worth. Once you have this setup properly there really
should be no need to reset the devices to factory settings.

> The Internet feed is a simple DSL line via the 2WIRE2701 modem. The
> thought is to disable the wireless capability of the 2WIRE2701 (there is a
> control panel option for switching it off) and connect one of the four
> RJ45 Ethernet ports on the 2WIRE2701 to each of the two D-Link DI-524
> wireless access points via a physical CAT5 Ethernet cable. Each D-Link
> DI-524 would be powered form a local source. Each would be located near
> the opposite ends of the building.

Probably not opposite but more like the lobes of a barbell. As in:

|-------------(*)-----------------------------(*)-----------------|

> I'm plan again to try the tandem configuration recommended by Bill Kearney
> in his post wherein the DHCP is disabled on the second-in-line router.

No, leave it enabled in the central router, the 2wire unit. Disable it in
the others, configure them as just dumb access points. This way you'll only
have to deal with DHCP and other settings on the one router. You could use
one or the other of the Dlink units but it's six of one, half-dozen of
another. If you use the 2wire you'd be able to reboot the wireless units
independently without losing connectivity on the other. Likewise if you
temporarily need to add more wifi routers it'll be trivial to set them up as
an access point and nothing else.

But you're still going to be faced with the interference problems. This may
not be solvable without cooperation from the other device owners.

-Bill Kearney

From: seaweedsl on 24 Apr 2008 11:42
I''m thinking the same as Bill's suggestion; assuming that you are
using omni antennas (makes sense here), set up your routers not at the
very ends but in the barbell shape, maybe with a third in the middle.

Considering that you are trying to cover a long area, you may want to
go ahead and keep the 2-wire radio operating as well.

Placement is going to be everything. Luckily, your area is only 30 ft
wide, so it will be a line, not a grid. Try to set up so there is
always an AP within 2 walls of any user.

Here's a suggestion:
Make a map of the walls and the needed coverage to play around with
locations for the APs.
Place one AP two walls in from the end of your desired coverage. Go
four walls over and place the middle router. Go four walls further
and place the end router. Hopefully you have now covered the whole
thing. Make sure that your middle router is on a different channel
than your end ones at least.

Who knows if it will ever work with all the other APs that seem to be
present. I would do a site survey first to see what the channel
mapping currently is. You might be able to prevail upon one or two
key AP owners to switch channels so that everything works better.
Failing any of that, doing it blindly, I would assume that most are
set to channel 6 and that using 1 and 11 for your APs will help.
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