WIFI Nightmare

[abatesholland]

Hi,

 

I was just wondering if anybody could offer me any advice on some robust wifi hardware to use in a primary school?

 

We currently have three Meraki access points in our school. We have removed our ICT suite and are moving down the route of mobile devices. We have 16 x ipads, as well as 15 laptops. We are looking to purchase more mobile devices in the future. Our current WIFI network is already struggling. All of the classrooms have good coverage, but the access points can't handle all of the devices connecting at the same time. Today - a class used 14 laptops to insert photos from a network drive into a word document. As children viewed the network drive, the WIFI network ground to a halt and were unable to view the pictures and insert them.

 

We really need a WIFI network that can cope with a whole class accessing it at a time. I just wondered if anybody on here could recommend some hardware that is up to the job?

 

Thanks!

[twin--turbo]

Unfortunatly your finding out that wireless and portable devices as a solution to whole class I.T. is problematic and once that can be costly to sort out efficiently.

 

Wireless networks are inhernatly less able to support large number of clients , not because of their speed but because of the way in which each client device gets it share of the bandwidth. You reach apoint where devices are trying to send data and just can't.

 

The solution is higher density of access points and reducing their power so the cover smaller more defined areas, traditonal wifi only realy has 3 available non overlapping channels so you have to plan their locations very carefully to avoid overlap.

 

 

Your Meraki may be inteligent and the AP's sort themself out, if that's the case then a few more AP's strategicaly placed may help.

 

Otherwise you may have to upgrade to a Controller based wireless lan.

 

All the big vendors have something.

 

Meru

Meraki

Cisco

Rukus

Xirrus

 

These will either work on a single channel or adjust settings on the AP's automaticaly to work as a WHOLE.

 

 

None of the above is probably of much help as the solution unfortunatly is to get a couple fo vendors in to do a site survey and propose a solution that will work. and HOLD THEM TO IT!

 

 

Some guys here have had good success with UNIFI though , and I have used other products from Ubiquiti before.

 

 

We use Meru, but 80% of our wireless clients are "THIN" so the network load is quite low. Where we got forced to retro deploy 30 Laptops performance is not so great.

 

Rob

[localzuk]

If you want to use high density deployments, coverage is not the issue, number of access points is.

 

Say you want 15 laptops in one room, those 15 need to have something that can take all those requests for air time. Meraki, as far as I remember, isn't built for high-density, high-bandwidth applications. So, if you wanted to continue using it, you'd need to add more APs.

 

Most high density deployments go for the standard of around an AP per room. That way, you've got at least a few in range of any dense usage, and they should split themselves amongst the APs.

 

However, this also requires a system that handles distribution of clients at the 'controller' (be that a distributed, central, cloud or whatever controller) side.

 

We use Ruckus at our place, and it is really good at dense deployments, so its definitely worth a try - people like Net-Ctrl can usually set you up with some trial gear.

[kearton]

What model Meraki APs have you got?

[catch21]

I guess you've seen this, quite informative...

 

http://www.edugeek.net/forums/wireless-networks/124210-what-wireless-network-hardware-do-you-use.html

[Net-Ctrl]

Hi @abatesholland if you were interested in discussing Ruckus and as localzuk said loaning some eval equipment I can get one of the sales guys to give you a quick call. Feel free to PM me if you're interested

[Haptic]

Have PM'd

[Oaktech]

We use a lot of laptops (3x full class sets of 30) in our transition school (year 7-8) and the 3 main teaching rooms for those years have a Unifi standard in each room and these regularly do those full class of clients on the domain quite happily, however I think the real point here is that those three rooms have no more than 20m between access points and they are flanked closely by 3 additional points in communal areas and the controller sorts them out for power and channel. It's not the brand of the access point that is the issue here, it's how many of the little blighters you can pack in, and how smart they are capable of being between themselves.

[twin--turbo]

to realy understand why wifi is a nightmare over copper you need to understand the differences in the way colissions are handled.

 

Wifi uses Colission Avoidance,

 

Carrier sense multiple access with collision avoidance - Wikipedia, the free encyclopedia

 

Lan used Colission detection.

 

Carrier sense multiple access with collision detection - Wikipedia, the free encyclopedia

 

Rob

[m25man]

I just spent an hour battling with a Toshiba C850 unable to get a consistent connection on a Unifi Pro.

Around it I had 27 other devices everything from phones to Thinkpads.

Having done all of the housekeeping and cleaning up it was still running like a pig.

Updated the Toshibas Realtek Wifi driver and bang... everything is running perfectly.

[twin--turbo]

We had a bit of a battle with C850's too this time last year.

 

Rob

[abatesholland]

Hi,

Thanks to everyone for the replies. Really helpful tips.

In response to kearton's question....we're using three of the Meraki MR16s.

[psydii]

Try putting the three ap's into one room with the laptops.

 

I am assuming here that they present the same network name with the same setting, with one ap on each of the available 2.4Ghz channels 1, 6, 11.

 

You should now see an improvement in performance form your wireless clients as they will load balance themselves (if their drivers are any good) across the three APs in a crude channel layering fashion. This is the method I used to provide reliable wifi in high density environments to 100+ devices in 2003-2005, however I also had 3x 5Ghz channels as well.

 

The key to high density/high bandwidth is channels per location. You really can't get good logon/logoff performance with more that 20 devices per channel per location. Further to the number of channels you also need to be aware of the clients aerials/radiochains. 1x1 radios are fine in tablets or BYOD where there is no high bandwidth spike at a critical moment, but for institution provided devices that support roaming users, you really need 2x2 or ideally 3x3 and at least two radio channels.

 

Basically you need at least two radios per Access Point (2.4Ghz 5Ghz) supporting 3x3 and you need to make sure that for users that roam between devices, these devices have at least 2x2 radios capable of 2.4 and 5Ghz communication.

 

Finally if using Windows 7, you should install the enterprise hotfix rollup (and the other hotfixes listed in the associated KB), the latest File Sharing technology hot fixes (List of currently available hotfixes for the File Services technologies in Windows Server 2008 and in Windows Server 2008 R2) and ensure that you are running the latest drivers for your wireless adapters.

[neilmac]

There are some misconceptions in this thread and some information that's well intentioned but plain wrong.

 

Before thinking about which vendor to select you have to think in terms of the users, the experience you want to give them and how you want to manage them. (Scope). You also need to get a figure in mind very early on as to how much you want to invest in the solution. (Budget). Finally, you need to set a date for when you want to have an install complete - complete means it measurably met the design targets.

 

The longer a project goes on for the harder it is to affect the outcome, so you need to make the key early decisions correctly. If you are struggling then get expert help but beware of approaching vendors or resellers too early as they will push you to buying their solution, you don't get a balanced perspective that way. You also need to ensure you are getting advice that is correct. You should seek expert help to get you underway.

 

I will try and correct some misconceptions from the posts above, I don't want to seem I am getting at individuals who have been good enough to post help for you, however you need to make informed decisions and can't if people give you bad information.

 

1) WiFI uses contention mechanisms so all devices will get their turn to transmit their data regardless of how many devices are present. Throughput will fall with more devices so the key is to keep data rates high, re-transmissions low and cell sizes small. All devices get their turn equally.

 

2) Client devices do not load balance, if you had 3 access points in room the clients attach to the one with the highest SNR. Systems with a control plane can use load balancing.

 

3) a 3x3 access point with a 1x1 client behaves more or less like a 1x1 access point, so unless your client devices support higher HT MCS rates, there's no benefit to having superior spec AP's.

 

4) Roaming is a decision ALWAYS taken by the client station, regardless of the spec of the AP.

 

5) The key to high capacity planning is maximising data rates and minimising retry frames. Smaller, lower powered cells, intelligent use of 5GHz channels as much as possible and you need to learn about wifi to understand what's going on.

 

6) Adding another access point onto a channel where there is already an access point and client stations, and they can all hear each other, will not add capacity. You are just adding another device that needs to be quiet while someone else is transmitting.

 

7) Anyone who tries to sell you a system should be able to answer a number of technical questions about wifi to demonstrate their abilities. If you are spending a lot of money and putting a system into an educational facility, you would want expert help, right ? Too often these networks are installed by people who really don't understand WiFi. Don't take the chance.

 

NM

Edited September 29, 2013 by neilmac