Wireless Routers used as Access Points only

You are correct in your wiring scheme, and in your wired configuration. For the wireless configuration, set the two routers to use different channels. At least 5 channels apart is ideal, at least 3 channels apart is acceptable. You probably want to use the same SSID on both routers, even though you likely won't be able to roam due to the different manufacturers.

Ron Bandes, CCNP, CTT+, etc.

He will be able to roam; he just won't be able to do WDS. But he doesn't need WDS, because he can connect the two APs via Ethernet.

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Tis best to use channel 1 and 11 for two co-located aps as there is some overlap between 1 and 6 and 6 and 11, just not as much as between 1 and 2 or 3 or 4 etc.

Actually there is, because the spectra extends well beyond the alleged occupied bandwidth. Maybe an explanation will help.

802.11b/g direct sequence channels are 5 MHz wide[1]. 802.11b/g direct sequence spread spectrum (DSSS) modulation looks like a sin(x)/x curve, with a big major "lump" in the middle, a drop to zilch on either side of the lump, and then smaller lumps going of into infinity. See tutorial at: photo of the DS spectra is what I'm muttering about.

The width of the "lump" in the middle is about 22MHz wide. The bulk of the RF is concentrated in this 22MHz or about 4+ channels wide. 5 channels per signal is a good average.

However, much of the RF on the slope of the "lump" is relatively low level when compared to the peak power. If you have sufficient physical seperation to reduce the signal even more, it is possible to run a system on perhaps every 3 or 4 channels seperation instead of 5. However, if the radios are in the same "air space" and can hear each other, every 5 channels is considered safe.

[1] Frequency hopping spread spectrum channels a 1MHz wide.

Y'er 98.7% correct. If you can't hear the potential source of interference, you will not have a problem and can use the same channel. However, if there is a location, where a real user might hear BOTH access points, you'll have an interference problem. In my limited experience, unless you have a very well isolated system, there will usually be some place on the premisis that can/will hear both access points.

I'm sorry, this is not correct. There is absolutely no spectrum overlap between 802.11b/g channels 1, 6 and 11. Check it out for yourself in any good WiFi book. This is where the "5 channels" rule-of-thumb originated.

-Jonathan

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originated.

I have checked it out. (found it in some good wi-fi books) It happens in co-located APs. The reason is due to the fact that they are transmitting at approximately the same degree of power and are close to each other. This will cause a small overlap between 1 and 6 and 6 and 11 around the 2.427 and 2.447 freq area and will typically decrease the throughput from approximatley 5mbs to around 4mbs. Theoretically there is no overlap but in reality there has shown to be some.

Just a question I have about this, since I started the thread. Does it really matter since the first wireless router cannot even reach the first floor? I get "0" signal strength and no connection at all. I have tried several different laptops with different cards and I get nothing at all on the first floor, so I am to believe that the signal from the one on the first floor will not reach the second floor either.

Thanks Steve

It depends on the construction. I have run into things like metal beams in floors, firewalls etc that really screw up propogation. Depends on your needs on the other floor. Not sure of your setup, but have seen a hardwire from one floor building to another, with multiple AP's. Wasn't meant to get into AP stuff, but more to mention that it is very typical to find "dead spots". The strangest I ran across was what I thought was a simple square brick pole, turned out to be metal inside with a brick facade, and just to make it stranger, the room had plastered walls (turned out there was a metal mesh under the plaster!) (older building, guess that's the way they constructed stuff then).

That doesn't matter if you're going to run a cable from the wireless router on one floor to the wireless router on the other floor. Or does that *not* describe what you were thinking of doing? If you want to have the two floors connected by a wireless link, that can't be done using the two routers you currently have.

My intent was to have a AP on the first floor since the WirelessRouter on the second floor will not reach the first floor, The router and AP on the first floor will be hardwired to each other, I have had two laptops running side by side walking thru the first floor and I get no signal at all at the places people will be using the laptops.

Thanks for the info guys!!!

I believe this is wrong. There is no standard for any Distribution System, not just Wireless Distribution Systems. IEEE 802.11F is in trials, but it's not standardized yet.

Ron Bandes, CCNP, CTT+, etc.

I believe you don't understand that the term "roaming" normally refers to multiple access points connected to the same wired network and having the same SSID and encryption key. Whether or not it's standardized, it works with access points of different brands, as they don't need to communicate with one another wirelessly.