Realworld Wireless speed and errors

[michaelhess]

I've got 4 1130ag's, three at one site and one at another.

I get just about 2Mbps over them. I've limited the AP's to only use G speeds per Cisco's docs, I've verified the ethernet port on the 3560's they plug into, they transfer at real 100Mbps Lan speeds, easily over 2Mbps Speakeasy test on my laptops over the wire is 8Mbps, over the AP's it's usually only 1.5Mbps.

I should get more than this with B! I'm using linksys wpc54gs ver 2 and Belking F5D7011 cards on around 20 laptops. Speed tests were taken on each individual AP with others powered off and no traffic to the two test machines (1 server and 1 laptop). The linksys card is slightly slower so I think it may be a driver/XP issue. I've downloaded all the latest drivers to no avail.

I get a LOT of errors in the ap stats screens:

Retries: 10408

Packets With One Retry: 6728

Packets With More Than One Retry: 1734

Duplicate Frames: 564

CRC Errors: 122

This is over 3 speakeasy tests and one 33MB file transfer test with the Belkin. There are no other wireless devices, phones, etc in the same band. Open air from about 10-15 feet from the AP's

Any ideas would be greatly appreciated.

[hrios]

I doubt this has anything to do with interference. Reset your AP back to its defaults, then setup the AP with nothing else but Open Authentication. Do not use any type of encryption (WPA can sometimes cause weird behavior) Then run your tests and see if you get better speeds.

[michaelhess]

I got called out of town on business, I'll definately try all of these suggestions when I get back. Thanks!

[mikraus]

There have been some reports of other wireless products "bending the 802.11 rules" that make them act as bad 802.11 neighbors. This is not in relation to interference, but rather inflating the duration values within the 802.11 frame. So, unfortunately, it's not always just as easy as looking at signal/interference.

Do you have an 802.11a client adapter? If so, you can attempt to use that for access. At the very least, if this does fix your issue, it would eliminate a configuration problem (replicate your configuration from the do0 radio to do1).

I'm not saying this is a solution, but rather a method to further isolate the problem.

If you experience the same throughput over the 802.11a interface, there is something else at hand...

[michaelhess]

I do just happen to have an orinoco gold laying around. I'll try it on A and see what happens. Thanks!

[michaelhess]

I finally got it figured out. I dropped power on both radios to 14dBm and set client power local to enable and limit client power to 11dBm. I tried every combination and with it set like above I started getting 22.47Mbps from two of my NIC's, the others are a little slower but that's due to range and it's well over the 2Mbps I had been getting. I guess it was reflections. I now have another issue I will start a new post about.

Thank you guys so much for your ideas and input, you've been very helpful!

BTW: I still get alot of errors, is that just the nature of the beast?

[john.preves]

Hey glad to hear it is getting better.

you should not be getting more than 2% errors in my opinion. anything more than that and there is still some tweaking to do.

14dBm is still 25mW-ish...how much real estate are these two AP's covering.

What I would do is determine how much space one AP can cover without ill effects and what power setting, antenna configuration, placement etc..that turns out to be.

with that information you can perform a site survey that is based on credible data and see how many AP's you need. You might need lower power and more AP's than you think.

[michaelhess]

One is covering a two story 1700sq foot house/office, tri-level. One is covering a single story office building with about 20 small offices, a perfect square and the ap is in the middle. And two are covering two wings of another office with about 10 offices per wing arranged like an H.

If I drop the power, I start to quickly loose throughput to my farther away devices which are currently getting almost 18Mbps, I think I'm at the optimal power for them. Coverage is actually perfect, it just barely reaches outside the building and I can get 18Mbps or greater anywhere in the buildings. Kinda strange 14dBm worked the same in all buildings though....The house is wood frame, two of the offices are mostly cinderblock and brick, hence the two ap's in the H shaped office.

I don't know about the errors, what else can I tweak? The configs are default with wpa-ent enabled at this point and the lower power settings. I guess if I get 22Mbps I can't really complain even if there are a bunch of errors right? There is no latency to the rest of my network and nothing seems to be corrupting during file transfers.

[john.preves]

Ok how is this for an educated guess -

You are looking at coverage and throughput as your main objectives, which is good but i haven't seen anything so far regarding signal quality (except for ScottMac in the second post.

The question here should be " at what signal strength / signal quality do I have when I have achieved my other two goals?"

Data is very forgiving since if a packet doesn't make it to the destination the first time it gets re-sent until it does. Same in regular networking as wireless.

If you had that many errors on a switch, a big red bell would be going off in your head.

Sure, everything works but it is not very efficient. If you are ok with this, that is a choice you have to make, because the answer is going to be spending more money on infrastructure.

You should have no less (in my opinion) no less than a 20dB fade margin to pass data sucessfully. Some people would say 25 but hey..

I would be looking at what my signal strength is in dBm (please, percent means NOTHING) and the quality of that signal with the handy Cisco Site Survey tool and a continuous ping from the AP and then the switch and then beyond the switch to something else.

You also need to consider the number of users per AP as this is also a cause for errors.

Obviously you are probably going slower than you need to be - but if no one is complaining...just so you know the more users you add the worse it will get.

[michaelhess]

Should I be getting better than 18-22Mbps? I only have 4-8 people connecting per ap at a time, sometimes less. My switch's aren't getting any errors at all, so it's only on the radio side.

I don't care how many errors I get as long as the data gets to where it's going fast enough, latency is virtually non-existant so I'm not worried about that either. I know that may sound ineffecient, but as long as I don't have a lot of users I don't think it will matter. Please correct me if I'm wrong though. I will mess around with my client devices and see what dB they show in various situations.

[john.preves]

It all depends on your environment and how close the users are to the radio. A survey would answer that question, I have no idea.

At some point you have to make peace with it and either accept what you get or run cable.

Sounds like you are at least better than you were and thats good...

[exatxer]

What type of laptops are they? I have had issues with the new dell latitude 620's with the intel cards. It sounds goofy, but if you turn the power setting down in the wireless card properties to 3/4, the connection improves 10 fold. It took me many days of troubleshooting before I came across an article on Intels site.

[michaelhess]

I actually have one 620 on my network, it's always had issues with my AP's, I did drop the power and it works better, but at times it won't even SEE the AP's. Hoping Intel has an update soon that will improve things. My other systems are working great now.