Wireless limitations - computer lab

[Duke5A]

I've got the CAD teacher at our high school wanting to turn the lab into a modular one. The end goal being able to move the tables around at will so that the students can break into groups for different projects. There are 35 computers in the lab and two to a desk. She keeps inquiring about wireless as a means to achieve this, but I'm not entirely certain it will lead to a good experience. Admittedly my knowledge is severely lacking in this area as our tech is a full ten years behind the curve.

 

Our wireless infrastructure consists of three Cisco 4404 controllers and 1142 access points (gig Ethernet, N wireless radios). What I was thinking was perhaps removing the 1142 AP from the room and setting up three newer WAPs that can do AC with only the 5Ghz radios enabled. It would be completely separated from the current wireless network.

 

I have reservations that wireless can handle the workload in a lab environment, especially with one that does CAD. What do you guys think?

[nicholab]

I would not want a CAD suite running on Wi-fi my view is domain joined machines are pain on Wi-fi. Could you not have pc round the edge with tables moving in the middle for the all together group activity. Otherwise you need chrome books with a gpu aided vdi system to back it up. Edited September 11, 2018 by nicholab

[3s-gtech]

Just because it's CAD, doesn't mean the network would be doing any particularly heavy lifting. If you want modular and flexible, desktops won't suit though (try getting students to move a whole suite of them and see how many monitors you lose). However, 35 at once would be a push, no matter the software, unless you can split the devices to multiple APs. Logon times alone will suffer under that throughput.

[AlanD]

WiFi is typically not a replacement for a wired suite of computers.

 

Don't be taken in the suppliers/advertised claims of gigabit WiFi…..that is only going to happen in an isolated barn with no surrounding WiFi...where you can use 80 or 160MHz wide channels...and all the clients are multistream...and possibly support MU-MIMO.

 

Typically - even the latest WiFi kit in a dense school environment is going to deliver somewhere between 100 and 200Mb/s to a client. And its not going to deliver those speeds simultaneously to all clients - but shared between those clients. And if your wireless clients are not multi stream, MU_MIMO and don't support "ac" then speeds will be worse. Expect 10 minutes for a class to logon - possibly more. Note the "connection" speed you see, and often quoted is UDP not TCP..and assumes perfect spatial separation of streams - which in the real world only gives a 25% or 50% uplift at best. And because wireless is a medium with packet collision detection - the efficiency falls off pretty rapidly when you have more than around 15 clients. In a dense environment "ac" rarely offers any significant increase over "n" because of being restricted to narrow channels (to reduce co-channel interference and the size of the collision domain).

 

35 BYOD tablets would be no problem for WiFi….

 

35 PCs...a nightmare....

[PotNoodleTech]

Sounds like a bad idea to me - we keep all our IT suites wired as is it so much faster and more reliable.

 

I recently upgraded my APs from 1142n to 2802 and they are MUCH faster with more capacity for future expansion. One AP per room. I still wouldn't put an IT suite on wireless though as it's a pointless waste of expensive WIFI capacity when you already have it wired.

 

Just my 2p!

[psydii]

It can work fine. It also can be a disaster.

 

If you keep as much as possible local to the machines (no roaming profiles, no appdata redirection) and don't require sync of redirected folders (e.g. documents) at logon then you stand a good chance of making it work. Having a Seating Plan, or matching students to devices also makes a huge difference to whether this approach is successful.

 

We have 30-40 students doing Photoshop work over 80Mhz wide 802.11ac (backed by gigabit Ethernet), it works *really* well. However if they all upload their SD cards at the same time, things get a bit slow. But this is understood and seen to be a class management issue.

 

I've seen a class full of students doing premier work too - this did require the teacher to get them to work locally and copy their projects and resouces up and down rather than calling them over the network in real time.