Forum

I concur - "11n AP's in non-HT (b/g) mode have superior communication with legacy devices. "

And if you're going to buy a new access point, why not just buy the 802.11n one now, use it for 802.11b/g and turn on the high throughput when the devices finally catch up.

Not roaming properly is an understatement. We also use H-REAP in this one particular building, which is doing its best to make me pull my hair out.

During my investigations, I have found that 802.11n clients don't roam properly and take forever to let go of their last AP. I've had to turn the adapter off and on again in order to try to make it roam.

Tim. (CWSP now..)

tdennehy Escribi?3:

I concur - "11n AP's in non-HT (b/g) mode have superior communication with legacy devices. "

And if you're going to buy a new access point, why not just buy the 802.11n one now, use it for 802.11b/g and turn on the high throughput when the devices finally catch up.

Not roaming properly is an understatement. We also use H-REAP in this one particular building, which is doing its best to make me pull my hair out.

During my investigations, I have found that 802.11n clients don't roam properly and take forever to let go of their last AP. I've had to turn the adapter off and on again in order to try to make it roam.

Tim. (CWSP now..)

Are these specific 802.11n clients or ALL 802.11n clients? I know some 802.11n netbook clients had some issues.

Just the sample that we had to test with (coworkers' laptops, personal laptops, a Symbol scanner)simply because the place is empty 99.999 percent of the time. It's a basketball stadium concourse which will be full tonight, so I'll have plenty of information this evening. The Symbol ticket scanners are 802.11b only, and they roam flawlessly. My personal laptop with a Cisco a/b/g card works just fine. My laptop has an Intel 5300 card in it and doesn't roam very well. Same card in coworker's laptop has same result.

I'm going to do some more investigating today and see what I come up with.

In the netbook issues you've seen, what was the fix? Reboot or shut off the card and make it associate to the closest AP?

tdennehy Escribi?3:

Just the sample that we had to test with (coworkers' laptops, personal laptops, a Symbol scanner)simply because the place is empty 99.999 percent of the time. It's a basketball stadium concourse which will be full tonight, so I'll have plenty of information this evening. The Symbol ticket scanners are 802.11b only, and they roam flawlessly. My personal laptop with a Cisco a/b/g card works just fine. My laptop has an Intel 5300 card in it and doesn't roam very well. Same card in coworker's laptop has same result.

I'm going to do some more investigating today and see what I come up with.

In the netbook issues you've seen, what was the fix? Reboot or shut off the card and make it associate to the closest AP?

With the netbook case, some single-stream 802.11n 2.4ghz-only netbooks, specifically with the Atheros AR9285 Chipset refuse to associate period. They would not associate to 802.11n access points that advertised MCS rates 0 to 15. I believe most vendors have already come up with a fix for this, and it has nothing to do with your roaming issue.

With regards to roaming, are you removing any of the lower rates at all?

Thanks for that piece of information! We're seeing quite a few netbooks popping up on campus these days.

Regarding the lower rates, I have not trimmed any of the lower ones from 802.11n. I don't allow anything below 11mb/s on our a/b/g-only access points, but haven't done anything on the 802.11n's yet. I'm still "new" to 802.11n. But most of us are, I suppose.

tdennehy Escribi?3:

I concur - "11n AP's in non-HT (b/g) mode have superior communication with legacy devices. "

And if you're going to buy a new access point, why not just buy the 802.11n one now, use it for 802.11b/g and turn on the high throughput when the devices finally catch up.

Not roaming properly is an understatement. We also use H-REAP in this one particular building, which is doing its best to make me pull my hair out.

During my investigations, I have found that 802.11n clients don't roam properly and take forever to let go of their last AP. I've had to turn the adapter off and on again in order to try to make it roam.

Tim. (CWSP now..)

Did you try 802.11n on non-H-Reap APs?

GTHill Escribi?3:

Most definitely you should deploy 11n AP's since they love multipath.

It may sound counter-intuitive, but you probably don't want to deploy the AP's in the open arena. The problem is channel planning. Let's take 2.4 GHz for example, if you deploy more than 3 AP's in a space where they can hear each other on the same channel, throughput will suffer.

I'm speaking without seeing the building, but if it is possible to deploy the AP's behind the stands in some way it would be best. It is an outside in approach vs. inside out.

What brand of AP's are you using now? If it is Aruba or Cisco that limits you a bit.

If you were open to using a different vendor, it could open up some possibilities.

Aerohive - Excellent product with great meshing capability without a controller, but RF management is key for your deployment.

Xirrus - Nice array, but I don't think I'd recommend it for such a large area. I've never deployed it though so I'm going from what I've read.

Meru - Advantage of good transmission coordination and could work well.

Ruckus - I'm on a Ruckus kick right now since I'm doing the roadshow, but I have seen the technology do some amazing things. True beam forming (vs. chip based) has major advantages and I know it would work well for your situation. Mesh would be a huge plus.

Beware of the over saturation of AP's. Some vendors are notorious for using too many AP's, especially in situations like this.

I did a bit of Googlevestigating and it looks like you are at UK. I'm not too far away and would like to see what you have going on up there. Anyway, sounds like a fun project!

GT

How does "Cisco Limit you a bit" in this deployment?

It would be good to hear what vendor(s) you have used personally in a similar deployment and what specific features you have found that are beneficial to the situation that Tdennehy has. If Cisco is limited, please provide specifics based on what you have experienced.

I came to my conclusion regarding the 802.11n clients not roaming since we're using H-REAP in that building and the two locally switched SSIDs are WPA2-PSK. Therefore, they are 802.11a/b/g only, and those clients roam beautifully. I used a Cisco a/b/g PCMCIA card and works great while roaming. Same PC with an 802.11n card, just doesn't perform.

I guess I should run some debugs on an 802.11n MAC addy that's roaming around and see what happens. I have noticed some 802.11n cards roam better than others, which doesn't surprise me.