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Wireless Networks Thread, Does this sound any good to you? in Technical; We have just had a wireless survey done, and are now waiting for the quote. We have had several different ...
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    button_ripple's Avatar
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    Does this sound any good to you?

    We have just had a wireless survey done, and are now waiting for the quote.

    We have had several different opinions but nothing like this. What we need from our wireless network is complete coverage of our school site which originally going to power 30 pupil laptops and 30 teacher laptops. This is soon going to expand to 1 laptop per pupil.

    Normally people suggest 1 access point per classroom, but we have just been recommended to have 1 really large cisco access point to cover 6-7 classrooms. Any idea if this will work effectively?

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    One would assume if its a large purchase it would be going to tender so you'd have at least 3 companies offering the survey/quotation for your own peace of mind.

    I don't know the answer for you but we have 32 AP's to cover our site with 150 wireless devices and it works fine, if a little too close together.

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    Michael's Avatar
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    Normally people suggest 1 access point per classroom, but we have just been recommended to have 1 really large cisco access point to cover 6-7 classrooms. Any idea if this will work effectively?
    There are several reasons why I would never recommend this. Firstly it's not always possible to centrally position a single access point (in any building) and you'll most likely end up with areas with a strong signal and others a weak signal. It depends on the age of the building and thickness of the walls too. And secondly you have no redundancy. If that single access point goes down (for whatever reason), no one can logon, or move temporarily to another location to logon.

    One site which I was hired to work at had 4 access points installed in the corridor across the whole school. This meant the signal had to go through a nice thick wall, (weakening it in the process) and logging onto 20 - 25 laptops was taking in excess of 15 minutes. There were other factors, but your original idea is spot on. By installing an access point in each room, the signal will be as strong as possible giving you the best results.

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    dhicks's Avatar
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    Quote Originally Posted by button_ripple View Post
    Any idea if this will work effectively?
    That's what the company selling you the equipment should be able to answer. They should be able to explain, exactly, with diagrams if neccesary, why they think one access point is adequate.

    --
    David Hicks

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    maniac's Avatar
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    I would always go for the 1 per classroom option, as the thing to remember with wireless is that 54mbs is divided between all the devices using the access point, i.e 30 laptops and you're talking less than 2mbs per device, and that is the main reason for slow logon times. If you have one big access point serving 3 or 4 classrooms, you're talking smaller and smaller bandwidth availability per device, which will slow things down even more no matter how good the signal is.

    Mike.

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    FN-GM's Avatar
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    One thing to keep in mind is don't have to many AP's close together. In my school we had 2 near each other, the laptops couldn't decided what AP to use they kept disconnecting from one and connecting to the other.

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    maniac's Avatar
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    Quote Originally Posted by FN-GM View Post
    One thing to keep in mind is don't have to many AP's close together. In my school we had 2 near each other, the laptops couldn't decided what AP to use they kept disconnecting from one and connecting to the other.
    Yes we had the same problem. Some of our larger areas like the library had 3 APs put in them for some reason which was totally OTT. Just because the room is bigger doesn't necessarily mean there's going to be more machines in it, but the company who installed the system 4 or more years ago obviously thought this would be the case.

    As long as there's an AP in the room, the coverage should be fine. Even our school hall only has a single access point, and coverage in the whole room is fine.

    Mike.

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    FN-GM's Avatar
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    Just adding to what manic said its not the size of the room. Most AP's can manage a big room as it has no walls blocking the signal. Its not the size of them room you need to watch out for its pesky walls.

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    RE: Wireless

    Coo, lots of cool stuff with wireless.

    Wireless signal can vary a lot, its not so much walls that are the problem but what they are made of. Walls made of dense stone wont allow any signal through and the same applys to any thing with metal in, this includes that foam stuff with foil on the back thats used to line the walls in some places. Also metal piping and electrical cables can block or weaken the signal too.
    Add to the list very thick wooden doors as well.

    Walls made out of thin plasterboard, or breeze blocks dont usually drop the signal that much.

    How to do a wireless survey.

    1st - Get a floor plan of the building/area to be covered by wifi.
    2nd - Plan out roughly where you think good coverage will be achieved.
    3rd - Go round with a WAP that you are planning to use, extension lead, a laptop with say something like Netstumbler, plug in the WAP and actually walk around and see how far the signal travels. Try to position the WAP as near as where you think it is actually going to go. Draw out on the floor plan how far the signal travels and then move to the next location. If you start at one end of the building and work your way through you can build a wifi network with total coverage with no dead areas.

    ^ Thats the proper way of doing a wireless site survey

    Dont forget again depending on materials wifi signal will often bleed well through ceilings and floors so if you have any areas that are 2 floors or more you can use this to your advantage.

    Personal rule of thumb, I always survey to allow for plenty of overlap on coverage between wireless access points, there is a reason for this, if a laptop is on the edge of signal range of 2 x WAP's it will keep jumping due to a weak signal, build in a good amount of overlap and this problem doesnt occur (or it has not for me yet).

    There is also another reason for good overlapping, ok so we can get WAP's of 54Mbps but there is a lot of extra overhead with wireless connections so this pretty much reduces you actual data transfer (usable data not overhead) down to 27Mbps. Work that out between a class of 30 pupils and in theory you end up with 0.9Mbps per laptop and thats not without retransmissions etc, its not looking good is it. Ok so if a classroom has 1 x access point logging on will be a nightmare, now if the classroom had 1 x WAP but was also getting signal from another 2 WAPS either side of it then there is a far chance pupils towards the edges of the classroom will connect to the bordering WAPS, this way you can spread your users across more WAPS. This is of no use though if every single classroom is full with Laptops and all pupils are logged on.

    Some other dafts stuff.

    MultiWAP controllers, designed to optimize the WAPS and to give you the ability to control them easily, personal note I think they are a waste of money. Nothing wrong with good old Telnet or suchlike

    A very good manafacture of WAPS is Colubris, the cheaper ones are ok but the more expensive ones (I dont have a model number too hand) that retail for around 250 each if you buy them direct are awesome. They have more features than most people can ever make use of such as running VLANS, Multiple SSID's and lots of other cool stuff.

    There is also some legislation about the location of WAPS, off the top of my head they are not supposed to be closer than 1 metre (it might be 2) to any ones regular place of work ie a desk for a teacher.

    Well thats enough waffle.

    Now back to the original question, personally I dont think 1 x WAP can cover 6-7 classrooms.
    It would be worth asking for a detailed diagram showing the level of coverage that companys are going to garuntee after the installation.

    Any more questions feel free to ask.

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    tmcd35's Avatar
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    I would say that from my experience wireless and laptops for pupil use in generally a bad idea.

    On the wireless side, 1xAP can only really comfortably cover 15-20 laptops. In fact after 15 logons network access starts to get very slow. Also 15 laptops all logon at at the exact same moment in time, with profiles being transfered, etc, is not fun!

    For 30 laptops in a class room, you need 2xAP's. But this means making sure they are on the same SSID and their channels are spaced far enough apart as not to cause problems. One of the two AP's will always have the stronger signal, so all laptops will try to connect to that one first. It takes some 30 seconds for a laptop to give up on an AP and try the next - slow logons. The solution is to use different SSID for the AP, but this then mean the laptops can only be used with the one AP, no roaming.

    On the laptop side, batteries barely last one lesson - a complete school day with out extra batteries and good recharge management is impossible. And then there's how the kids treat laptops - missing keys, broken keyboards, etc. There's logon problems because kids don't check the wireless is turned on, there's profile problems (at least with Winsuite) because kids don't logoff properly. There's problems installing software via MSI because 1) wireless is slow and 2) kids are impatient - turn the laptop off/wireless halfway through the software install.

    In short, I don't think the technologies there just yet and there must be better solutions available than wireless and laptops for all. Perhaps Thin Clients on every desk. Computers around the edge of the room. More computer suites and a good booking system.

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    Vegas's Avatar
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    If I was to start again I would first get a heat map done of the buildings and then buy a managed solution with Aruba being at the top of my shopping list.

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    Pete10141748's Avatar
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    Quote Originally Posted by yabbadabba
    3rd - Go round with a WAP that you are planning to use, extension lead, a laptop with say something like Netstumbler, plug in the WAP and actually walk around and see how far the signal travels. Try to position the WAP as near as where you think it is actually going to go. Draw out on the floor plan how far the signal travels and then move to the next location. If you start at one end of the building and work your way through you can build a wifi network with total coverage with no dead areas.

    ^ Thats the proper way of doing a wireless site survey
    Thats actually what the guys from this company did, although they used a Linksys WAP not a a Cisco one (they claimed the Cisco WAP they are recommending is about 3x more powerful than the one they brought in).

    Signal coverage was not a problem, and never has been here - all walls are plasterboard and signal penetration is very high.

    The problem is capacity.
    Now, they claim that 1 of these cisco routers will easily handle upward of 90 laptops, and with the signal coverage combined they can be spread out over quite a large area.
    Obviously, the concern is that the WAP won't do this.

    Once the quote comes back, I'm going to ask that they come back in with the actual WAP they are recommending, and we'll get as many laptops as we can to log in using it.

    I reckon that 1 WAP for 6 classes is to little (even though the classes are a "cluster" all within approx.30meters of a central location where the WAP would sit) - 1 per 3 classes would be OK, so long as the kit holds up to what they are saying it can do.


    Quote Originally Posted by FN-GM
    One thing to keep in mind is don't have to many AP's close together. In my school we had 2 near each other, the laptops couldn't decided what AP to use they kept disconnecting from one and connecting to the other.
    This is exactly what we are trying to avoid given this solution, the idea being that there arn't enough WAPs to conflict with each other.


    Quote Originally Posted by TMCD35
    In short, I don't think the technologies there just yet and there must be better solutions available than wireless and laptops for all. Perhaps Thin Clients on every desk. Computers around the edge of the room. More computer suites and a good booking system.
    I totally agree. The technology just isn't around (or affordable) to allow something like this to operate smoothly.
    Unfortunately, it's what our Head wants, and despite spending the last 12 months trying to convince her of the issues, problems, costs etc. she is still determined that this is where the school should go, and so that's what is going to happen, one way or the other.

    I guess the real proof will be in the pudding, as they say.
    Once we choose a solution (whatever we decide to go for) and get it in and working, we'll see just how much it is used.

    TBH, I don't see staff making the use of it that the Head invisiges.
    Currently, we have around 20 laptops for pupils, all with completely dead batteries, dodgy wireless cards, crap processors and low RAM.
    Pointless to upgrade, and currently, pointeless to replace.

    No teacher uses then, as they know that even when the batteries were OK, what a P.I.T.A. they are. Now everyone goes to the ICT Suite, and they think it is so much better. Which I agree with.

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    White_Fi's Avatar
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    Hi button_ripple,

    Net-Ctrl Ruckus Wireless Techie here,

    I work for a company that resells Ruckus wireless which is centrally managed by a Zone Director, this will control the management of APs and users connecting to the network be they staff/students or indeed visitors. It also has some seriously cleaver APs that are designed to work out where noise is coming from and ignore it and pay better attention to the clients they can also mesh APs together so that an AP that cannot have an Ethernet cable attached can automatically route back via an AP that does have an Ethernet cable.

    Ruckus are doing very well with schools at the moment as they've got some awesome technology at a snip of the price of anyone else in terms of a proper centrally managed wireless solution.

    I was having a think about your single Cisco AP and that seems made not just from a signal point of view but the fact that both it's wired and wireless bandwidth is shared by all connected to it.

    I've had a quick chat with Mark Power our sales guy for Ruckus here and he's told me he'll come see you with an Ruckus AP to show and tell all about it and even give you an evaluation to check out as he's that confident you'll like it and the "nice" price.

    You can get him on 01473 281211.

    Kind Regards
    Stuart White

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    Quote Originally Posted by FN-GM View Post
    One thing to keep in mind is don't have to many AP's close together. In my school we had 2 near each other, the laptops couldn't decided what AP to use they kept disconnecting from one and connecting to the other.
    it depends on the type of wireless network device you go for. If you just buy "standard" off the shelf APs and stick them in a room then they will fight with each other. If you go for the Aruba, Cisco, Trapeze etc type systems then the central controller can do very clever things to adjust power levels so that the APs don't interfere with each other. this also means that even if you've got 2 APs close to each other, the laptops ought to pick up the one they're closest to and play nicely.

    I don't like the idea of one big point for a set of rooms (as in button_ripple's original post) - if that point fails then you lose everything which is surely not a good idea!

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    tmcd35's Avatar
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    Quote Originally Posted by Pete10141748 View Post
    I totally agree. The technology just isn't around (or affordable) to allow something like this to operate smoothly.
    Unfortunately, it's what our Head wants, and despite spending the last 12 months trying to convince her of the issues, problems, costs etc. she is still determined that this is where the school should go, and so that's what is going to happen, one way or the other.

    I guess the real proof will be in the pudding, as they say.
    Once we choose a solution (whatever we decide to go for) and get it in and working, we'll see just how much it is used.
    Our head likes the idea of laptop trolleys everywhere and teachers seem to want them, at least until they actually get them and realise how troublesome they are.

    We have around 20 laptop trolleys around the school. 16 Laptops are meant to be on each trolley. We have about 25 laptops sitting in our office in various states of disrepair.

    Not a day goes by when a student comes into our office complaining they can't log on because either - the last person didn't log off, the wireless on the laptop is turned off, or the AP in the room needs a restart.

    Then there's teachers plugging in the trolleys without turning the power strips off first, power surges and electrics are tripped. This happens weekly in one department and knocks out the power to the switched controlling a near by ICT suite!

    And to make matters worse - another department has just been 'awarded' their own laptop trolley. It's being installed this half term. All I have to say is thank good I won't be here after half term to see go tits up!

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