WAPs supporting upto 25 concurrent users

[raufdean]

We're using Cisco aironet 1100 wireless access points. These have proved to be very reliable.

 

The problem we're having is supporting 20+ users on a single access point. After about 15 have logged on, the other 5-10 cannot gain access to the network.

 

The client laptops are using Intel pro/wireless 2200BG wireless modules.

 

I've tried putting 2 access points on either side of the same room, and setting the channels on each to be very different, but no luck.

 

I think the issue is an RF one - I'm pretty sure there's no maximum client restrictions in the Cisco operating system. The Intel wireless modules are also (relatively) pretty old now..

 

Just curious if anyone else has achieved 20+ concurrent connections in a classroom with any other access point ?

 

Rauf

[localzuk]

The practical maximum for a single access point is about 15 - after that number, things become stupidly slow, rather than just rather slow. The optimal maximum is usually stated as being around 8 users per AP, but as a school regularly would have a class of 30 people using wireless, 10 would be normal, with 3 AP's serving them.

 

This isn't necessarily down to the access point itself, but think about what is being used here. Most AP's connect to the network via a 100Mbps connection - sharing that between 25 users would be ridiculous and only provide 4Mbps per user. That is very, very slow.

[craiglay]

Not forgetting the IP throughput being about 20Mbit/sec on a 54 access point!

[HodgeHi]

You could opt for an 802.11n AP which is supposed to support up to 50 connections at a time with a 1Gb connection to the network?

[FragglePete]

Just spoken to one of the technicians here.

 

With the two laptop trolleys we have here, each has a Devolo Plug-In Access point that is plugged into each room as each trolley is put out.

 

Now, amazingly, even though these bits of kit of 'domestic' they have been able to support both trolleys out in one room (ie. 32 Laptops in total).

 

I was somewhat amazed by this, but they really are impressive bits of kit. They also have an additional Data over Power module as well (included in the starter kit) which is used from time to time, but generally they are plugged into the a power socket with a Ethernet cable plugged into what is sometimes the only network port in the room and away they go!

 

The Model is the Devolo dLAN Wireless Extender .

 

HTH

 

Pete

[ricki]

I would not believe any claims of manufactures of being about to hold this many reliable connections. The most I have managed is 25 to a router and once I get above 15 the connection speed and reliability become that bad its not worth doing. Please note if you are running sophos and wsus performance and speed reduce even quicker.

 

Richard

[HodgeHi]

I have 15 macbooks and an airport extreme 11n router which is set up in bridge mode. I have not received any complaints of login failure from either both OS X or XP. They have even used iMovie across the connection although it failed poorly i think. I have had users using garageband across the wifi network though with no issues.

[sidewinder]

I think the issue is an RF one - I'm pretty sure there's no maximum client restrictions in the Cisco operating system. The Intel wireless modules are also (relatively) pretty old now..

 

We have exactly the same AP's as you and there is actually a setting for that, but its fairly useless because while it stops any more connections, the PC will just keep trying to connect to it rather than looking for another AP

 

And if we have 16 (one trolley) on one its very slow...any more than that and its just ridiculous. As we have no managed system we've just had to say maximum of 15/16 per room and even then they have to stagger logons

Thankfully this has got teaching staff finally realising that wireless really isnt that great when you want a whole class on computers

[raufdean]

Thanks for all the replies.

 

From an ethernet point of view ~1Mb / user should not be that bad. After all I can VPN into the school's network over my home contended ADSL connection and achieve perfectly acceptable results.

 

Sidewinder - your experiences sound very familiar!

 

FragglePete - Thanks for the link. I'll take a look.

 

Rauf

[raufdean]

You could opt for an 802.11n AP which is supposed to support up to 50 connections at a time with a 1Gb connection to the network?

 

 

Nice idea, but I'm stuck with 25 intel 2200bg wireless laptops for the time being

[torledo]

I have 15 macbooks and an airport extreme 11n router which is set up in bridge mode. I have not received any complaints of login failure from either both OS X or XP. They have even used iMovie across the connection although it failed poorly i think. I have had users using garageband across the wifi network though with no issues.

 

imovie failing miserably over a wifi connection.....no kidding

 

The only way we can use imovie over the network for a group of 10+ machines is at full gigabit speeds on the client, plus link aggregated ports on the server, plus a striped raid array for storing the imovie projects....anything else would fail horribly, especially over wifi which shouldn't even be attempted even for a couple of clients.

[localzuk]

The other option is something like the Extricom stuff, which can have 4 radio's per access point (so, it could be seen as 4 access points per unit). It also allows you to have overlapping AP's.

 

http://www.extricom.com/

 

A base unit (8 port) is about £3500 and a 4 radio AP is about £370.

[HodgeHi]

imovie failing miserably over a wifi connection.....no kidding

 

The only way we can use imovie over the network for a group of 10+ machines is at full gigabit speeds on the client, plus link aggregated ports on the server, plus a striped raid array for storing the imovie projects....anything else would fail horribly, especially over wifi which shouldn't even be attempted even for a couple of clients.

 

You gotta try though aint ya?

 

We managed to have a few on running iMovie. Its just some failed. The projects aren't huge anyway and the data was already captured. The users were just editing the footage.

 

The Users home dirs are stored on our XRAID which is connected to the Xserve via a 4Gb connection. The server is then connected to the network via a 1Gb connection. The classrooms connect using 10/100Mb/1000Mb and the AP connects to this in bridged mode which gives a 11n wifi connection to the Macbooks. It all works most of the time.

[torledo]

You gotta try though aint ya?

 

We managed to have a few on running iMovie. Its just some failed. The projects aren't huge anyway and the data was already captured. The users were just editing the footage.

 

The Users home dirs are stored on our XRAID which is connected to the Xserve via a 4Gb connection. The server is then connected to the network via a 1Gb connection. The classrooms connect using 10/100Mb/1000Mb and the AP connects to this in bridged mode which gives a 11n wifi connection to the Macbooks. It all works most of the time.

 

Our xraid is only 2gbs FC .... or should i say our xserve G5 fc card is 1/2gbps capable.

 

similar setup to yours, except our imacs connect to a gigabit switch in our core (cisco 3750), the xserve is two 802.3ad gigabit connections connected to the same core, used to be five copper gigabit connections, but we realised the performance bottleneck was the speed and setup of the RAID and not the network connection to the server, so we stuck with two gigabit connections. Our imovie projects are anywhere between 5 and 10 gig in size each, so we require a lot of storage space and good performance. footage is captured from the cameras onto network home dirs on the Xraid, and edited from there....works well so long as you've got everything setup correctly - a lot of trial and error and head scratching when stuff starts crashing.

[HodgeHi]

Too true about when things go wrong.

 

There is indeed a lot of head scratching.

 

That is one of the biggest down-sides to owning OS X in education in the UK. When things are problematic there ain't too many places you can go. Not in the midlands anyway from what i can see.

 

I have asked questions about server issues to the guys in the Apple Store in B'ham to see if they can answer but the Geniuses behind the Genius Bar can't answer them.

[torledo]

Too true about when things go wrong.

 

There is indeed a lot of head scratching.

 

That is one of the biggest down-sides to owning OS X in education in the UK. When things are problematic there ain't too many places you can go. Not in the midlands anyway from what i can see.

 

I have asked questions about server issues to the guys in the Apple Store in B'ham to see if they can answer but the Geniuses behind the Genius Bar can't answer them.

 

asking the 'genius bar' about apple server problems would be akin to asking my mother about quantum mechanics ergo you'd be better off talking to a brick wall....

 

what i've resorted to is the apple forums aswell as our apple reseller, when i can get hold of their server whiz.....although tbh i haven't contacted them much since the end of the project.

 

I kind of regret not taking out some sort of support package on our xserve, but tbh i'm glad i didn't for the xraid......i'm not a very big fan of it anymore, i think it does a fine job in direct attached configuration , but i'm not going to bother with putting it on an FC fabric and the non-redundant controllers are daft just plain daft - seriously handicaps it for any serious use, i've got a proper grown up IBM array for proper SAN......and in the not too distant future will have a netapp aswell hopefully doing NAS and SAN. woot.

 

in which case with any luck we'll be putting a 3TB+ xraid up for sale.

[HodgeHi]

Sounds very tempting that XRAID but since we are only a primary school i think it maybe a little overkill to have two of em

 

Personally i have no issues with the XRAID for performance. I net install my machines off it when needed. It hosts the pupils and Staff Home dirs and i install most of my apps from it using ARD. It does the job for us. I would like to be able to access it from either machine on the network but again over kill for us.

 

I am going to try and get the OD-AD integration working again soon though so hopefully it should remove some of the workload running two independent domains.

 

At the moment though all is ticking over OK.

 

I too resort to the Apple forums although they aren't the best source of support. I have also contacted our reseller (KRCS sold us some of our kit) and there is a guy there Tony Rocco (who also frequents teh Apple forums himself) who is great. He gives advice and support and is great to have. I just don't want to pester him too much especially since we don't have any support contract with them.

Edited March 4, 2008 by HodgeHi

[zag]

The current wireless protocols are simply not designed for that many clients.

 

I can't see how you can run a reliable room just over wireless.

[stevehead]

The current wireless protocols are simply not designed for that many clients.

 

I can't see how you can run a reliable room just over wireless.

 

Why doesn't anyone use the 'a' bands?

A cheap way of doing it is to put 'a' cards in all the roaming laptops (staff and such like). Put up a load of consumer grade overlapping 'a' Access Points to support these - they'll always be a lo density 'a' band hummm.

Then stick 3 'g' band cheapo (but choice, the WAP54G comes to mind) on top of the laptop trolley. A 5 port Switch, then cable to a free ethernet port in whichever classroom it ends up in.

That'll give you 60Mbps of WiFi in whichever room you like.

 

The 'a' band rocks for cell planning; sorely overlooked.

[spc-rocket]

Nice idea, but I'm stuck with 25 intel 2200bg wireless laptops for the time being

 

Hi there,

 

with the 2200 intel wireless the latest drivers makes a huge differance in keeping a stable connection. There are some tools available to diagnosie issues with RF interferance, one of them is something spy, i think its wi spy or similar which comes as usb stick lookalike device that shows you the RF interferance all sorts of stuff. I think they are around £150 - £175 but they are worth it in the long run as it helps with placing APs and doing site survey etc.

 

Ash.

[raufdean]

Hi there,

 

with the 2200 intel wireless the latest drivers makes a huge differance in keeping a stable connection. There are some tools available to diagnosie issues with RF interferance, one of them is something spy, i think its wi spy or similar which comes as usb stick lookalike device that shows you the RF interferance all sorts of stuff. I think they are around £150 - £175 but they are worth it in the long run as it helps with placing APs and doing site survey etc.

 

Ash.

 

Hi Ash,

 

Thanks for that - we're using the latest drivers...

 

the wi spy thing sounds interesting though...

 

Rauf

[Michael]

@raufdean - Sometimes when two access points are in close proximity, (even on separate channels) the results are mixed.

 

If however the laptops are on a trolley, you could setup both access points with different security, so the first 12 laptops automatically connect to AP1 and the other 13 laptops automatically connected to AP2.

 

Not the most ideal solution, but it would work and it would guarantee 25 laptops (even 30) working in the same room through two access points.

[mcloum]

Im having to come up with this sort of solution at the moment. THis is the way i was thinking of doing it. I dont see any reason why it wouldnt work tbh. Any other thoughts from anyone?

 

@raufdean - Sometimes when two access points are in close proximity, (even on separate channels) the results are mixed.

 

If however the laptops are on a trolley, you could setup both access points with different security, so the first 12 laptops automatically connect to AP1 and the other 13 laptops automatically connected to AP2.

 

Not the most ideal solution, but it would work and it would guarantee 25 laptops (even 30) working in the same room through two access points.

[White_Fi]

Hi Guys,

 

When supporting this number of clients on a single Access Point your AP must be extremely reliable.

This is where ZoneFlex AP’s from Ruckus Wireless comes into play.

 

We have a client that managed to get 32 clients on a single AP without any issues of loss of wireless performance.

::NOTE:: Link to the case study:

http://tools.net-ctrl.com/HelenswoodSchoolpressrelease.pdf

 

Please contact Mark Power on 01473 238211 for more info & an evaluation.

 

Regards

 

Stuart White

Network Security Analyst

Enterprise Security Solutions | Network Security Consultants

Tel: 01473 281211

[dtakias]

Im having to come up with this sort of solution at the moment. THis is the way i was thinking of doing it. I dont see any reason why it wouldnt work tbh. Any other thoughts from anyone?

 

It's definitely a good idea. Don't forget to play around with the options of the intel drivers on device manager, as there are plenty of them like roaming aggressiveness, power for transmission and many more...