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Network and Classroom Management Thread, Wireless AP's in Technical; We currently use 54g B/G AP's across site... there are obvious problems with logon using more then 8 machines to ...
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    Wireless AP's

    We currently use 54g B/G AP's across site... there are obvious problems with logon using more then 8 machines to any one AP

    The laptops all use 54g network cards. Ive monitored the bandwidth and sometimes the logon can be upto 50mb of data to everymachine.

    This I think it because of Sophos AV.

    Now, the new '802.11n' type is capable of 200 on average. We are confused about what route to go down.

    If we got this new 'n' type AP, then could we use the existings g cards and run say 4x 54g's definitly at a faster rate then a 'g' AP? Or would the AP slow down? OR do we need all new 'n' capable NIC's?

    Thanks for your support

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    Geoff's Avatar
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    Re: Wireless AP's

    You'll need to upgrade both the AP and cards to get the full benifit of 803.11n.

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    Re: Wireless AP's

    i would contact someone like dlink education sector. see what they advise, then use that as a way to move things forward

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    Re: Wireless AP's

    Th 802.11n draft 2.0 has just been agreed by IEEE members and the final draft should be completed in June 2008 so i would start planning but would not roll our N just yet. Wait till the later this year and if you are keen then buy the n kit as they will be able to be upgraded to full version when its ratified.

    I would also suggest that you buy the access points which support Gb uplink as opposed to 100mb because N standard does have a higher throughput than the rest otherwise the bottleneck may be the wired connection from AP to the Switch.

    Geoff is correct you need 802.11n compliant NICs to take full advantage and also it may be bit flakey to run it in backward compatibility mode. This is the kind of stuff i read on the net.

    I don't know if the NICs will be the mini-nics that you can swap out on existing laptops like the Intel 2200BG one.

    Intel may come out with the N standard one some time but its too early to tell.

    Ash.

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    Re: Wireless AP's

    Hi,

    On wireless AP's the bandwidth is shared which is why you may have a problem with multiple users signing on at the same time.

    This is a common problem for schools. In many ways schools are the most demanding wireless enviroments as you have many users (up to 30 in a room) all accessing the network at exactly the same time.

    To be open and honest I am the Education Account Manager for ONI, a Cisco partner so I deal primarly with Cisco and exclusively with Education customers. I am not going to push my opinion on anyone, just hope I can help.

    With a high quality access point the maximum users you want accessing it are 15 (and this is on a 'business' AP, a more SOHO AP is likely to handle less), so in a typical classroom we will position two access points. This creates further considerations such as the need for inteligent load sharing, ensuring the channels do not clash and that the signals do not overlap.

    The new N standard is not yet ratified (as far as I am aware) so it maybe a bit early to go there. It is also relatively expensive and will require both new APs and laptops/access cards. I would personally not recomend that yet.

    Hope that helps,

    Tom

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    Re: Wireless AP's

    A more inteligent load balancing system you say.

    Well, we have in some places added more AP's. So we'd have 2 points in a corridoor so laptops can use either. The problem we have there is that if its too far away around the corner but can just about see the AP SID.. it will still connect to it despite the very low signal and so it loses it.

    In 1 building we have 6 AP's. 3 called AP1 and 3 called AP2. I've found the laptops will connect to what evers closest. Is there a good load balancing system or is that exactily what you suggested?

    THe other problem is, we have the same setup in another building yet they have loooads of problems, alot less the the same setup elsewhere. I think this maybe due to the NICs built into the laptops as they are different.

    Cheers

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    Re: Wireless AP's

    techyphil what APs are you using? are they all the same?

    To have true load balancing you need a back end Controller for the wireless system that can understand what is going on with the wireless network and tell laptops to associate with the most appropriate AP. With Cisco they have something call CCX on the NICs that helps this process.

    In the case where the laptops are not associating with the closest/most appropriate AP it maybe because there is some channel/signal clash that is causing the signal from the further away AP to be the chosen one?

    As a temporary fix you could fix which laptops connect to which AP using something like MAC filtering - however this is only really useful if the laptops are regularly used in one place.

    cheers, Tom

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    Re: Wireless AP's

    In 1 building we have 6 AP's. 3 called AP1 and 3 called AP2.
    I believe that to be a bad idea to have mutlitple access points all called the same thing or do you mean they have the same ssid of AP1 or AP2?

    Ben

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    Re: Wireless AP's

    i believe you can set an update time with the sophos clients, there *may* be an option to stop them from checking for updates on startup.

    I know it doesnt solve the whole AP point, but it may help you till the N stuff is more mature.

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    Re: Wireless AP's

    I have nothing but trouble with APs. Viglen installed our network and the engineer didn't test all 20 laptops connecting in 1 classroom as he didn' have access to 20 people to log them on at the same time. So when he left all worked well, as soon as we came to log on 20 at one all hell broke loose.

    This was 2 years and only half of the machines could connect. Bandwidth bottleneck.

    I tell complained about how useless the access points were and then a new update was released for them and this took the number of connected machines up to 12 out of 20.

    I then complained some more and got the APs changed for better ones (old and new were dlink). 16 out of 20.

    Then there was an update for the intel wireless pro internals cards inthe laptops. 20 out of 20! It was the cards all along! But I am sure the new APs helped a lot too.

    But even now we will have 2 or 3 laptops that suddenly decide to not connect to the wireless profile prior to log on which needs an admin to log on locally to connect the profile then it works again for weeks and then bam, happens again.

    This chew on has lead me to believe that wireless networks are a bit of a black magic and have a mind of their own. All we can do it try to make them work as well as possible. I would love to hear from people who have a wireless network working 100% fine. If so I need their hardware!

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    Re: Wireless AP's

    We have a good relationship with some of the manufacturers, They say 9/10 AP were never designed to have the amount of clients as we do in schools, All connecting at the same time. Most reliable way we have found is to make sure that AP's signals overlap each other. (with roaming enable on the AP). So if a laptop cant get onto one, it can try another before failing. We use ZyXEL G-3000's as thats what we've had most luck with. But im sure there are some other good ones out there too.

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