Two access point a/b/g in bridge mode


Hi everyone,
we need a very reliable wireless connection between a laptop and a
small network of two other computers. We first tried with an ad-hoc
network with wavelan cards, but since usually there are walls and a lot
of interferences between the two ends, the communication is very poor.
We switched to one ap to wavelan pcmcia card, but this still has
problems, so we decided to use two access points in bridge mode or
server-client mode (which one is better?), but it is difficult to find
two access points with those characteristics (and that we can find in
Italy!)...
- 802.11a and 802.11g mode
- bridge and/or client-server modes
- one must have a switch, because it have to be connected to two pc
any ideas?
Reply to
MadMage
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Wavelan PCMCIA cards are the original names for the Orinioco/Lucent/Avaya/Agere/Proxim/Gold/Silver/Whatever cards. The really really early ones will only do 1 and 2 Mbits/sec. Later units has firmware and driver issues and were not tested with later operating systems. They usually function, but I'm not sure I would consider them the best choice if you insist on a reliable connection.
In my never humble opinion, you are NOT going to get any form of reliable wireless communications going through multiple walls and in the presence of interference. 802.11 was never designed to be jam proof in the presense of reflections with weak signals.
You haven't mentioned performance (speed), but if that's also a requirement, I consider it impossible. You can improve reliability somewhat at the cost of speed. I suggest you: Set the maximum speed to 2 Mbits/sec Turn on CTS/RTS flow control in the access point Decrease the fragmentation threshold to about 500 bytes. These changes will increase the sensitivity, do a better job dealing with interference, and decrease the size of the packets so that they have a better chance of surviving in the presence of intereference. However, it will be very slow on thruput.
What you are looking for is a "transparent bridge" or "workgroup bridge". These are wireless bridge devices that will pass more than one MAC address. For example, WAP54G, DWL900AP+, etc. Some of the "game adapters" (WET11) will also work with more than one MAC address.
If you really have interference problems, moving to 5.6GHz might not be a bad idea.
There is no client server mode. There are: Anfrastructure Ad-hoc WDS (wireless distribution service) Client mode with one MAC address Transparent bridge Client mode with more than one MAC address (same as transparent bridge mode.
Most wireless transparent bridges have only a single ethernet connection because they assume the customer will supply the switch.
If you forget about 802.11a 5.7GHz, I suggest a Linksys WRT54G with Sveasoft Alchemy firmware. This will give you *ALL* the aformentioned modes to experiment. See:
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I don't have a solution to the intereference or wall penetration problems. Those will be there no matter what hardware you select.
Reply to
Jeff Liebermann
That should be Infrastruture mode.
(That's what happens if I forget to run the spellin chequer).
Reply to
Jeff Liebermann
Hm, interesting. For regular usage, what would you recommend the RTS, CTS and Frag settings be? Defaults good most of the time? I know it's not much to go on and site will vary but, let's say for a regular small apartment line of site and 2nd situation would be a 3 story wood house? Just curious if anyone tunes/tweeks with these settings, experience-wise...... ;-)
Scotty
Reply to
Scott Nelson - Wash DC
The default settings for all wireless routers is to turn *OFF* CTS/RTS flow and fragmentation threshold. CTS/RTS flow should be enabled only if there are a large number of users battling for the attention of an access point. It also helps if there is interference. Fragmentation helps by creating smaller packets, which have a higher probability of arriving in the presence of interference. I don't really have a good set of values in you want to enable these. The smallest packet is 256bytes, but that's probably too small. 512bytes will work well enough. However, don't expect playing with these to improve the performance and speed.
Neither justifies turning on either CTS/RTS or fragmentation, unless you have an army of users or tons of interference. Leave the values at the defaults, which are essentially "off".
I do for WISP (wireless ISP) service. Anything installed outdoors, in a crowded city, will pickup interference. If the packet loss appears to be climbing, I start sending smaller packets. If I have a large number of simultaneous users (over 30), then CTS/RTS flow is required.
Incidentally, the value for CTS/RTS flow is the minimum packet size that will *NOT* use CTS/RTS flow. It makes no sense to initiate flow control negotiations for sending extremely small packets. One can resend 3 or 4 small packets in the same time that it takes to negotiate one flow control exchange. So, the setting determins the threshold of where larger packets get flow control and smaller packets simply get sent, and resent if they fail.
Reply to
Jeff Liebermann

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