Wireless Bridge

Some possibilities:

The DWL-900AP+ supports SNMP which might have signal strength. I'll check when I get home. MIB file for DWL-900AP+

All 802.11 management packets contain a field that has the signal strength. If you could sniff the traffic with a passive sniffer, you could extract the signal strength. I think (not sure) that Kismet, under Linux, will do this.

No, or at least probably not. The two antennas are intended for diversity reception, not to act as a repeater for clients on different antennas. The problem is that the access point often doesn't switch between antennas quick enough. It really depends on the algorithm used by whatever chipset is inside the DWL-3200AP. Sometimes it works, but my experience has been dismal.

I fixed one such problem with a power splitter connected to two antennas. Not the best or cheapest, but good enough.

Try measuring the performance going through this arrangement. In other words, going in one antenna, through the DWL-3200AP, and out the other antenna to the main building. If you get truely disgusting performance, it's not going to work.

What does "across it" mean as opposed to "through it"? Please describe the path the files follow.

Lost packets almost always means interference. Have you checked for other users on your selected channel? See the FAQ at: |

Won't work. I just looked at the MIB file. No signal, no noise, no nothing. It's a subset of the real ieee802dot11.mib file and is missing many things. Bummer.

Another problem. The SNMP MIB file comes with Dview 5.1:

Thanks for replying. The multiple antenna splitter is interesting. Would I have them pointing in different directions (or is it intended to just gather more strength from one direction)? Since you mention Hyperlink, I would like to add that I have ordered from them a few times and would recommend them to anyone.

With the lost packets I am thinking I'm just swamping the connection with data which it can't keep up with. I'm also wondering if I'm nearing the MAC limit. Does anyone know where to lookup the max number of MACs for an AP? I don't think it's interference since I'm in a very rural area. Trees are a bigger issue than interference.

Are you aware of any APs which have signal strength for a bridge?

Thanks again, JV

snipped-for-privacy@gmail.com hath wroth:

The basic idea is to prevent the access point from switching between antenna ports for every packet. Some of them just can't do it.

Antennas do NOT generate, create, or manufacture RF. The redirect it in various ways and directions. You can't get something for nothing.

In transmit, a power divider would split the RF signal in half between the two antennas. Each antenna would now have about -3.5dB less gain. This may be a problem. In trade, it allows you to customize the antenna pattern to be the combination of the two antennas. If both antennas were pointed in opposing directions, you would get the rated transmit gain of each antenna, minus the -3.5dB divider loss.

However, in receive, the loss is only -0.5dB. Each antenna acts with it's normal gain, minus the -0.5dB.

Where things get messy is where the antenna patterns overlap. Your highly directional dish and omni are going to be a problem. When there are two paths to the power divider, the RF can either cancel or reinforce depending on the phase of the RF signal. That happens every half wavelength. Your combined pattern will look like a "fan" or "daisy" with lots of weird lobes in odd places. The power splitter trick only works if you have physical isolation between antennas. That's great with sector antennas, and two highly directional antennas. It won't work with an omni.

They're a mixed bag with me. Their return policy and proceedure is abysmal. However, it's been about 2 years since I've bought anything from them, so things may have improved.

"Swamping" is not a very useful term. My guess(tm) is that you're feeding camera images at a faster rate than the wireless can handle. Eventually, the buffer overflows (somewhere), and drops packets. Let's do the math. You mumble that your video clips are 5 to 50 Megabytes large (40 to 400Mbits). Your radios are 802.11b. That has a maximum data thruput of 4.5Mbits/sec. My guess is you're getting much less thruput thanks to the double hop (store and forward bridging) and possibly lousy signal strength. I would give it an optimistic

On which unit? The WAP11/DWL900AP+/MA102 boxes are limited to 32 MAC addresses (including their own MAC addresses). Do you have 30 clients connected through the bridge? I don't know about DWL-3200AP, but my guess is well over 256 MAC's.

It's difficult to find on the low end units. In fact, it's difficult to find any data on low end radios. I did it with a proprietary AP and client simulator software used for lab testing radios. I just cranked up the number of simulated wireless associations until something broke. Some access point gracefully discarded old MAC's in order to make room for new associations. Most just locked up and died. All the units with SNMP will display the MAC address table.

Trees will ruin your signal strength and force the radios to slow down in order to maintain a reasonable data rate. Other than trees, do you have line of sight, Fresnel zone clearance, and have you done a site survey for interference? You might be suprised.

Not off hand. I'll have to dig for that info. Most of them do not.

Have you tried Kismet to extract the signal strength and S/N from over the air packets? You don't need to install Linux on a laptop. Just boot a LiveCD such as Security Auditor: