Since the last forum was locked, I have traveled to IlliniWireless's WISP in the great State of Illinois. I performed a packet capture and have been analyzing it off and on for quite some time. I'm going to post my results as I observe them. There seems to be a lot going on here. The main capture th...

It is a channel (PHY Layer) limit, not the units. Most of the time cheap AP's off the shelf will have the same throughput as an expensive Cisco AP. The difference is the consistency, features and reliability. Figure about 1/2 actual half-duplex throughput for the respective data rate. 11Mbps data ra...

Illini,

It probably is a driver problem, but I still think that I will see what is actually happening by performing a capture.

Gene

Who is the closest person to Central Arkansas having this problem? I know a guy in OK and one in IL having this problem, but is anyone closer? I'll come look at it for free to get this thing figured out.

Gene

I haven't as of yet, but Mukah emailed me and let me know that he would have them soon.

Gene

I have poured over the captures today. Unfortunately I don't have the full captures yet, but Mukah is sending me some more. Here is what I have found so far: During normal operation, the CPE's send a Probe Request to the proper SSID. The next packet shown (remember, I can't see packets from the AP u...

I did receive the captures today and will spend some time on them this afternoon.

Although mismatched preamble can cause compatibility problems, they are a go / no go thing, not intermittent.

Gene

I know that the ACK timeout thing keeps coming up, but an ACK timeout problem doesn't have much to do with the symptoms that I have heard. If the ACK timeout was wrong there would be serious issues once all devices associated. I have wondered if the problem exists because too many devices are trying...

I cannot stress enough that the next step is to see a packet capture of the attempted association. I will ship a laptop ready to go if that is what is necessary. I'm not trying to make a $ on this... I'm just trying to help. I want to be that hero of the month.

Gene

Surfnet, An AP should disassociate all clients before a soft reboot so that would be normal. If a client doesn't know that it is has been disconnected and keeps trying to send data, it will timeout after 64 (default for most clients) retries. 64 retries would take around a second to happen. After it...

Illini,

I completely agree. This is not a problem with the clients. When I get a capture I'll be able to narrow it down. I may stop by your location on my way to Chicago and do a capture. I'm hoping to get a capture from another WISP before then so I can work on it.

Gene

If this was a problem with the client (CPE) then why does the problem go away when people change their AP? If it were just a problem with the client, this wouldn't be localized to just a few AP models. The more I think about this the more I think this isn't the problem. If this were the problem it w...

ACK timeouts are something that most enterprise AP's don't have so I can't experiment with it, but I would definitely try setting it manually. Somewhere in the 50's sounds like a good place to start.

Gene

An ACK timeout is designed to change to accommodate long distance shots. If the ACK timeout is too low, the AP will not receive the ACK back in time because it takes longer for the ACK to come back, due to longer distances. If the AP doesn't get the ACK back in time, it will retry the data and then ...

The original poster and I talked about this last night. He is going to send me a capture in the next few days. I'll keep everyone up to date.

Gene

Brad, You must have a compatible card before Omnipeek will work. The Ubiquiti card I mentioned is a good one but there are others if you don't have it. The nice thing about the Ubiquiti is that it has external antenna connectors so you can point to the AP from your CPE and get both sides of the conv...

I would love to be the hero of the month. That packet capture is the place to start. If no one wants to set up for packet capture I can send them a laptop ready to go.

Gene

I just got off the phone with one of the WISP owners on this board. He told me some more details and it is definitely a compatibility problem. I believe it is a problem in how the devices are handling association. The next step is for me to look at a packet capture of association. If anyone has the ...

Hey everyone, I got a PM from a different site that I frequent. I work on a few WISP's and am a WiFi instructor and CWNE. That doesn't mean I have all the answers, but have some experience. Has anyone done a packet capture? I have found a number of problems with CPE's and AP's by analyzing the captu...