Medium Sized Grade School to go wireless...

Unanswered Question
Oct 20th, 2008

First of all let me say thank you for taking the time to read this.

This is my first time dealing with a wireless network larger than the range of a single building.

Currently we have 165 computers on our network, 144 of which are wired connections. The other 21, because of their place on campus are connected with one of three WRT110's acting as WAP's.

Our switches are filled, and it is time to either buy another, or take the direction wireless. After long discussion, as long as the price is not astronomical, we have decided that taking the campus in its first real step towards wireless is the way to go.

I am working on getting the actual dimensions needed for coverage, but as a visual, I'd say one and a half to two football fields long, and one to one and a half football fields wide.

The goal is to have any new computers join the domain wirelessly. What would be the best solution or (if you can't offer a solution) the best direction to take this. Is there a single wireless switch with a few boosters and a few access points to solve our problem?

Please note: security is not currently a major concern of ours and the capability of a simple mac filter will suffice for now. (Small private school)

Again thank you for any suggestions you may have.

-Kris "Techahashi"

I have this problem too.
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Techahashi Wed, 10/22/2008 - 05:07

Maybe I should be more specific- what pieces of hardware should I look to buy from cisco to accomplish coverage of the area specified (keeping in mind there will be few wireless users to begin with but will eventually grow to somewhere around 100).

Again thank you.

gamccall Wed, 10/22/2008 - 13:15

There are two entirely separate questions you need to think about when you're planning a wireless deployment: the physical layer issues of getting enough radio signal to the areas that you want to cover, and then the upper layer issues of addressing, management, and so forth.

The space you've described is, very roughly, 200,000 square feet. Using Cisco's rule of thumb of 5K ft2 per AP for data applications, you're looking at about 40 APs - but that will vary dramatically depending on how many obstructions of what sorts you have to deal with. If it's a wide-open space, many fewer; if it's a library with bookshelves to the ceilings every four feet, there's no way to guess. You're really going to want to take an AP and a laptop into the space and see what your actual propagation looks like; there's no way to tell for sure without feet on the ground.

Once you have an idea of how many APs you need and where you'll be placing them, on to the upper layers. You have to decide whether you want to manage each AP yourself as an autonomous device, or whether you want to run a lightweight solution where the management decisions are made on a controller device ("wireless switch" to some people) and then pushed out to the APs automatically. Lightweight is much more convenient, but is more expensive since you have to buy the controller(s) and related software.

Regardless of whether you decide to go with IOS or LWAPP, it's certainly possible to boot your wireless clients into the domain. You'll need to be running a RADIUS server- Cisco ACS or Microsoft's IAS, or there are others- which will process authentication requests and pass them along to your AD. You'll set up your wireless security mode as WPA or WPA2 using PEAP, and there are a few knobs to tweak on the wireless clients to make domain authentication work automagically, but it's very doable.

You'll also have to consider the question of whether you want your wireless clients on the same subnet with your wired users, or in different VLANs. Different VLANs is usual, but you have to think about whether your wireless users will need access to resources on the wired user subnet and how to arrange that if needed.

And with all that said: I don't ever recommend wireless as a replacement for wired connectivity. It's great to be able to pick up and go and get your email and check CCO when you need to, but it's an enhancement to a wired network, not a substitute. You need to have someplace you can jack in when you're doing real work, because wireless bandwidth is a shared medium, it's vulnerable to interference, and sometimes it's just plain flaky. So if your choice is between more wired drops to support the new users, or the wireless, my first answer would be "Both!" But my second answer, in almost any setting I've ever seen, would be to run the Cat 5.

Techahashi Thu, 10/23/2008 - 04:29

Thank you very much. I think for the time being I will discourage a full wireless network around the campus, buy another 48 port switch and run the lines, and just add the WAP's as the need arises. What wireless switch would you recommend for the initial implementation but also considering the growth expected in the future?

Again thank you very much.

gamccall Thu, 10/23/2008 - 05:35

Cisco's wireless controllers are priced based on number of APs supported: There are controllers sized for 6, 12, 25, 50, 100, and (as a blade for a Catalyst 6500) 300 access points. So it's just a question of buying enough capacity to support your number of APs, with an extra controller for redundancy if you care about that. (It's a good idea; if your controller fails then your APs are offline.)

You can have multiple controllers on a network, so you don't have to buy all your capacity at once; however, if you go this route then you'll probably want to get the WCS server software which will manage all your controllers simultaneously.

For the time being, you might just go with one or two controllers and skip the WCS, then add additional controllers and the management server when you're ready to expand.

rob.huffman Thu, 10/23/2008 - 05:31

Hi Kris,

I really think that Gabriel has given you some stellar tips here (+5 points for this Gabriel :)

You probably want to look at the 4400 Series of Wireless Lan Controllers (known as the WLC - see attached)

Cisco 4400 Series Wireless LAN Controllers (with good video)

One thing to keep in mind when purchasing the WLC is that the number of AP's that it can support cannot be increased via upgrade, so think of future expansion of the "wireless" project when making the initial descision. So if your total deployment will be approx. 50 AP's don't buy the 4402-12 (12 supported AP's)

One other suggestion is to buy a new switch that supports PoE for the type of AP's you will use. This way the AP can be powered via the CAT5E and no additional power will need to be run to the "Hotspot" locations.

Best of luck, wireless is a great add-on to any good network. And the students will love it :)



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