Wireless Setup at School

[stewysb119]

I am a middle school teacher who has been put in charge of setting up the school's wireless system. They chose me out of "Hey you can do it" mentality.

I have a simple DGL-4300 Router at my home that I have set up and have working fine, so they guess I think I can handle this task.

We have huge amounts of bandwidth coming into the school. My latest speedtest had us at 75000kbps ( I have hit 90k with no one on in the evening). The school is set up in Pod buildings. I have roughly $500 per pod to spend per pod.

The requirements are that I have support to connect as many as 35 Macbooks and MacBook Pro's simultaneously per pod (as many as 250 could be connected school wide if all the school's laptops were all connected at the same time). All of the systems are brand new. The District gives us a 26 digit password that we MUST use to secure the wireless system.

2 Questions:

1) Should I have one very high power wireless system for the whole school, or set up smaller routers in every pod to maximize performance?

2) What hardware do I look at, and where do I buy it?

Any help with this project would be greatly appreciated.

 

[scotty]

Typically, you don't see most places impliment a single, 'big and powerful' wireless system or device - you tend to see a distribution of smaller access points across the campus. They do make some bigger systems, but they tend to be expensive and/or proprietary. You can buy better antennae for most access points though, if there's areas where a single AP needs to provide better coverage.

At the simplest level, you can just buy a bunch of inexpensive Acess Points (AP's) and configure them with all the same settings, and plug them in at various pionts in the 'pods'. The only thing with this is that there isn't really any central control over the units or the acess, and Windows (not sure about OSX) isn't terribly smart at 'roaming' from piont to point (windows won't necessarily connect to the strongest signal). Virtually any AP would do the job here, although some are built a little more rugged for certain applications than others (better contruction, better annenae).

Another option is you can go for a mesh system, which is basically a bunch of low-cost access points repeating off each other. More details in this thread.

Moving up from here, you get into a centrally managed Wireless system, with a central control unit controlling all of the various access points. Unfortunately, I haven't seen much here cheaper than $2000 for the central switch/control unit so this is probably out of your budget. Here's some of D-Link's offerings.

Combined with good wireless security practices, such as segmenting the wireless network from your regular network, individual AP's or a mesh system could do the trick. It would be quite a slick as a fully centrally managed wireless system, but it would definately suffice.

 

[thiggins]

1) Should I have one very high power wireless system for the whole school, or set up smaller routers in every pod to maximize performance?

A distributed system with multiple access points connected to an Ethernet backbone will perform better than one "high power" system for many reasons. Note that access points do have a limit on simultaneous users. It varies and isn't usually well documented. But practically, the number is typically between 16 and 32.

2) What hardware do I look at, and where do I buy it?

What is your total budget (you didn't say how many "pods" you have to cover)?
What is the square footage of each pod and what is the interior construction like?
What is the target per-user bandwidth?

 

[stewysb119]

What is your total budget (you didn't say how many "pods" you have to cover)?
What is the square footage of each pod and what is the interior construction like?

There are 8 Pods (separate buildings) with 4 classrooms in each pod, aprox. 2500 sq ft per pod. The rooms are separated by typical drywall construction with a hallway type workroom in each pod. The school is brand new.

What is the target per-user bandwidth?

I know the wired connection coming into my classroom downloads at 75-90,000 kbps and uploads at 8-10,000 kbps according to speedtests. As far a specific per user bandwidth, you can assume 50 users per pod max streaming low definition video. We would like to be able to use the video conferencing features of the macbooks as well. The typical student user will be doing internet research, downloading media files for iMovie, Powerpoints, etc... The macbooks are all brand new with 802.11n airport cards built in.

I hope this helps.

 

[thiggins]

I think you need to sharpen your pencil and get a good handle on the bandwidth requirements.

Let's say a video stream is 0.5 Mbps (I just did a quick measurement of an MSNBC live stream with NetMeter). If 50 users simultaneously stream, that's 25 Mbps.

Typical real-world close range throughput from a draft 11n AP is, say 60 - 80 Mbps.

So you might be able to handle 50 simultaneous streams from a single AP from a bandwidth view. But I don't know the max users per AP. To be safe, I would plan at least two draft 11n APs per pod. A sketch of the pod would help determine best placement.

Of course, you will need each AP connected to Ethernet.

 

[scotty]

My guesstimate would probably be about the same, around 2-3 AP's per 'pod'.

Also, as Tim suggests, a bit of planning of 'actual' throughput required would be good to do, based on soft and hard counts. And different video conferencing applications can take different amounts of bandwidth. You might want to check into the particular apps you might be using and what the particular bandwidth requirements are. Also keep in mind, as Tim alludes to, real-world bandwidth is far different than advertised bandwidth. As Tim says, real-world bandwidth is probably around 60-80Mbps for N, and 20-25Mbps for G - with optimal conditions and excellent signal strength. These can be cut in half or more as you add range. You'll also have people doing other things, surfing the net, downloading, etc. which could affect things. There are things that can be done to prioritize certain kinds of traffic though (QoS). But that's another discussion.

Some brands of certain AP's, like D-Link's, have software to help to centrally manage/monitor a number of AP's, so that might be worth looking into.

 

[stewysb119]

I really figured the 50 as a max. Realistically I don't see 2 full carts of laptops simultaneously streaming that much.

I received an email from the one of the IT guys downtown today. \ The school district is frowning on us spending the time and money to set up our wireless system, but they want us to wait another year before they will address the issue. They basically feel that we should be happy with what we have.

My principal reminded me that what I was doing was a temporary fix that only needs to make it a year.

I think I'm going to start with 1 AP per pod and see how it goes. Setting up another would not be that big of a deal.

I was thinking of D-Link DIR 655's as the routers. If you guys have any others that are within $50 that pack better range/features, let me know.

Thanks again for all the Noob support I need.

 

[YeOldeStonecat]

I've done a couple of "budget setups" for small businesses, and one very small school, using DLinks managed WLAN offerings. Centrally managed via their DES1228p POE switch, using the 3140 thin client APs that look like smoke detectors in the ceilings (they pull their config file from the management switch). They do auto load balancing for large numbers of clients.