WLAN for my school, how to proceed best?
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I know that some of you have a bit of experience with planning big WLAN installations, so here's just a simple question as to which of two ways you'd proceed:
My school already has a number of access points (usually one per two class rooms) but it definitely seems that we're reaching the limit of what they can cope with. We've received the okay (actually, more like a command!) by our superior department to not think in "small business" terms but to use the "big business hardware".
Which results in two scenarios:
a) We simply put additional access points into every room which currently does not have one. This has the advantage of being a quick solution we can start almost immediately.
b) We let a company do a simulation to determine the optimal layout of the access points. This takes more time and also may force us to move existing APs.We're not sure how much crosstalk / interference professional access points automatically deal with and if that's even an issue in our case. In case it is indeed an issue, we'd need the simulation, of course.
So, any suggestions?
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@Rhywden do you need to support 2G devices? You say there's roughly an AP every other room? What's the approximate room size? And what makes you think that you're maxing out your current wireless infrastructure?
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@Polygeekery No need for 2G - we'd also like to use (somewhat) future-proof stuff like ax.
A typical room is roughly of this size:
So, make that 10 by 7 meters, roughly.
And we think that we're hitting the limit due to seeing WLAN connection problems / bandwidth issues in rooms where multiple people are trying to connect to an online ressource at the same time while wired connections in the same room not suffering from such issues.
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@Rhywden said in WLAN for my school, how to proceed best?:
@Polygeekery No need for 2G - we'd also like to use (somewhat) future-proof stuff like ax.
A typical room is roughly of this size:
So, make that 10 by 7 meters, roughly.
And we think that we're hitting the limit due to seeing WLAN connection problems / bandwidth issues in rooms where multiple people are trying to connect to an online ressource at the same time while wired connections in the same room not suffering from such issues.
It's not impossible that the problem is too many APs, rather than too few - given my baseline assumption that the walls between classrooms aren't structural (brick / concrete / steel) walls but are just drywall/plaster, only 15-20 meters between APs is pretty tight and you might actually be getting self-interference.
Especially given the directive from on high to "not think in small business terms", I'd definitely look at getting a company experienced in the space to do a site survey & simulation, and expect to move toward a Cisco Meraki (or similarly priced option from a different vendor) infrastructure. The primary differences with Meraki / "business grade" hardware over just standard APs is:
- The central controller does some channel coordination to minimize self interference
- The AP hardware & software is better optimized for 30+ concurrent connections per AP
- The AP software is set up to provide explicit support for managing roaming between APs and to "direct" clients to an appropriate AP based on signal strength and AP contention, which gives you better (and still automagic) management of client count and a slightly smoother experience as clients roam throughout the building
I would not recommend just slapping more Linksys-grade APs into the current environment without a site survey, unless you have definite (SNMP or manually monitoring AP stats) data showing which APs are being saturated from a traffic capabilities perspective. Which is usually pretty hard to get from Linksys-grade APs to begin with.
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@izzion Our devices are Cisco/LANCOM - definitely not consumer stuff.
I'll inquire, though, as to what capabilities of monitoring the AP stats we have.
Thank you!
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@Rhywden what's the current hardware? What's the rough average load and rough load when you see contention?
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@Polygeekery said in WLAN for my school, how to proceed best?:
@Rhywden what's the current hardware? What's the rough average load and rough load when you see contention?
As I said, Cisco and Lancom. The other two I cannot really answer.
However, it gives me an idea what the questions are ;)
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@Rhywden said in WLAN for my school, how to proceed best?:
As I said, Cisco and Lancom.
I was on mobile and did not see the reply at the time. Also, I don't pay attention to....well....anything. :)
@Rhywden said in WLAN for my school, how to proceed best?:
The other two I cannot really answer.
Roughly speaking, and a WAG is fine, how many devices are in the area of said APs when you see contention issues?
I'm with @izzion. It is extremely likely that you could have too many APs instead of too few. I would also just make sure your bases are covered and that you are running the APs on gigabit connections and if possible confirm that they are connecting at that speed. We have run in to similar issues before and part of the problem was bad cabling causing the negotiated connection rate to drop to 100Mb. If that is happening, you have major issues.
Problems like these can be basically anything. Can you get ahold of any sort of diagram or blueprint of the current wireless deployment? I know you have an entire campus and if you have such a thing it would be a lot of information, so maybe narrow it down to just the area that has the most frequent issues? If you could send that to me, or post it here, I would be happy to take a look at it and see if anything jumps out at me as an obvious issue.
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@Polygeekery Uh, I can run around and mark the APs for one floor for one of the smaller houses.
The amount of devices? Well, in my class alone that would be 25 laptops + 25 mobile devices.
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@Rhywden any sort of layout diagram, as long as it is somewhat dimensionally accurate would be helpful.
I saw it asked earlier but I don't know if there was an answer, what are the walls made of?
Do you have any sort of access to the backend controller of the wifi? One simple metric that can tell you if you are too dense on your deployment is to look at channel utilization. If you see high channel utilization in some areas, it can be helpful to graph that data over a period of time. If for instance you see high channel utilization during the day when the building is full but it drops significantly at night while the building is empty and devices are either gone or idle, then you are maxing out existing APs.....ooorrrrrrrrr, you are deployed too densely and/or have your AP transmit power turned up too high. When you have APs as dense as yours are you typically have to turn the tx power way down. Lots and lots of sysadmins and installers leave it at the default (max tx power) values.
I've said it before and I will say it again, wifi deployment is as much art as science. But I will guarantee one thing and that if you bring in a group to do a site survey I will pretty much guarantee that their advice will be to pay them to rip it all out and install new and shiny hardware. Whether they end up actually fixing anything when they do is another story entirely.
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@Polygeekery said in WLAN for my school, how to proceed best?:
you are deployed too densely and/or have your AP transmit power turned up too high. When you have APs as dense as yours are you typically have to turn the tx power way down. Lots and lots of sysadmins and installers leave it at the default (max tx power) values.
The way I always try to describe this to laypeople to try and make it make sense is this: In your case imagine that you have 10 tables in a large room. The room would be the building, the tables would be the rooms inside of that building. At each table you have 6 people each having a conversation. If everyone keeps their voice at a low or moderate level, then everyone can hear each other fine and everyone can communicate. But if one person at each table is screaming at the top of their lungs then no one can hear anyone else and no one can communicate.
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@Polygeekery I'm not sure what the walls are made of - might be bricks, might be concrete, might be plaster (we have a mix of building from the 70s, 90s and from five years ago). Will have to ask. Accurate diagrams I have, though.
We'll have a talk with our IT support on Monday so I can ask what measuring capabilities we actually have in place.
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@Polygeekery But what I'm taking away from this: The "quick" solution would probably not the best of ideas...
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@Polygeekery said in WLAN for my school, how to proceed best?:
deployed too densely and/or have your AP transmit power turned up too high.
This. It's actually somewhat surprising how effective making APs squawk quieter can be...
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@Tsaukpaetra Which reminds me (still haven't gotten around to drawing the positions - Friday was too densely packed with other stuff) - our existing APs already try to not step on each others toes by automatically using channels they see as "not used as much".
However, what I'm also seeing is that individual APs will thus change channels in rather rapid intervals - like every 10 seconds or so.
I guess that's also not quite optimal?
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@Rhywden said in WLAN for my school, how to proceed best?:
like every 10 seconds or so.
Ouch yeah that's not that great...
In theory they should settle once they decide which channel is best. I know in the last I've had to stick my APs still because shitty firmware, but APs shouldn't be trying to emulate Bluetooth Lol...
