Wireless Access

Hi all,

 

i'm new to Aruba and to high density wifi as well. I read some good thing here and also found some formula, but i'd like to have some more info.

 

We will have some classrooms (with about 30 students) with a size of about 40m2 close to each other. Then it seem difficult to have more that one AP per classroom as it would result in channel collisions/congestion i guess, right ?

We are thinking of using AP embedded controller, there will be about 15 AP (about 15 classrooms)

I know that 310/320 serie AP could have a great density, but been able to have many connections do not mean been able to have speed for everyone.

One first thing i do not understand : 310 has 1x1Gbps link, 320 2x1Gbps link, why ? Wifi will never have such a throughput and then will never need such link, am i mistaking ?

 

use of the wifi will be citrix, then at least 2Mpbs is needed, 5 will be better.

 

But is one AP able to handle such thing ?

This also will be a BYOD system, we will have many different capability : 2.4 or 5 GHz, wifi b, g, n, ac ... and if everyone is speaking a different protocol will it result in congestion or so and if  a device is able a 5Ghz that should be important to "force" it to use 5GHz to leave 2.4 for others, right?

 

Any though about all of that is welcome

Thanks !

 

If you have not already, please see the blog entry here:  http://community.arubanetworks.com/t5/Technology-Blog/Choices-choices-which-Wave-2-AP-is-right-for-me/ba-p/279704

Hi Colin,

 

thanks for this interesting link.

Our choice was between 315 and 325

But i can see differences that i can not understand :

 - 315 is doing 4x4:4SS MU-MIMO and 325 "only" 4X4:3SS

 - but 325 is also doing 4x4:4SS SU-MIMO

- 315 has 160Mhz channel, 325 is 80MHz 

 

-> i really can not tell what is better or not and why

 

 

---

@Cedimp wrote:

Hi Colin,

 

thanks for this interesting link.

Our choice was between 315 and 325

But i can see differences that i can not understand :

 - 315 is doing 4x4:4SS MU-MIMO and 325 "only" 4X4:3SS

 - but 325 is also doing 4x4:4SS SU-MIMO

- 315 has 160Mhz channel, 325 is 80MHz 

 

-> i really can not tell what is better or not and why

 

 

---

Not many clients support 4SS or SU-MIMO.  What is important is that if you want to do high density, the AP325 has a more powerful CPU than the 315, which allows it to process more clients.  I would go with the AP325 for higher density deployments (>30 users on an AP), and it will also future-proof you.

Ok, this is clear.

either 1x325 or 2x315 then... But i guess 2x315 will perform better then (15 connecion per 315)...

 

I read many about AP or IAP, and IAP seems to be really interesting, do you agree that we can get rid of a controler ?

2x315 could perform better.  It is up to you.

 

With regards to controller vs. instant.  It comes down to preference.  Do you have wireless now?

What do you mean by "Do you have wireless now?" ?

Yes i have wireless in my company but a very small one.

About Aruba i never tested it.

About cluster i only tested little cisco wap 121/321

 

About my customer nothing is bought at the moment.

We are thinking of buying one 315 and test it with a lot of devices on it.

 

I hope that i reply to you :)

The reason why I ask if you have wireless now is to find out what you prefer.  A controller-based deployment only requires you to basically configure the port that connect the controller to your network.  An Aruba Instant deployment will require you to trunk every network to all of your APs.  Asking if you have wireless is a way to determine what your network deployment preference is..

ok, understood !

 

I already configured cisco controlers for customer, i'm not really confortable with that...

For me a "virtual" controler as many brand are now proposing is more clear, and also eliminate a SPOF

With Instant, you can avoid the cost of a controller and licensing, but you would have to trunk any VLANs that you want users to be on to every access point.

 

What kind of wireless were you running?  guest, student, 802.1x?  Captive Portal?

I guess we will have 2 vlan only : one for studdent and a guest

No captive portal.

Wifi that i already install only had two vlans : data and voice.

Trunking vlan to AP do not seems to be a big problem !

 

In that case, you can use Aruba Instant without a controller.  If you feel that you need a controller, you can purchase one and convert the APs to campus APs.  You just need to order the Instant Variant of the 315 or 325; whichever you decide on.

Ok perfect, like for cisco AP -> LAP.

 

Is there a big impact if there is heterogeous devices type : a, g, n, ac, high-end laptops, entry-level laptops...

Will "old/bad" client slow down new one ?

 

really thanks for all your replies.

There is an airtime fairness configuration that can mitigate that:  http://www.arubanetworks.com/techdocs/Instant_423_WebHelp/InstantWebHelp.htm#CLI_commands/arm.htm?Highlight=fairness

 

In most deployments, I am not sure that I even see that enabled, but it is there if you need it.

Hi Colin,

 

great to know, that, i can have a test with that

 

Thanks

Hi,

 

when talking with a reseller, i was told that ap 205 could be enought due to that student's laptop won't have latest wifi protocol and then won't take advantages of ap 315.

Cost is less than i could buy more 215 and have less device per ap

 

Is that correct ?

Thanks

You should probably talk to your reseller about that, to make sure that you are making the right decision.

How are you planning AP redundancy? If the one AP fails what then?

The 315 is imho able to do 30 clients. But if you talk about 30 student the number of devices is more in the area of 90 then 30. Everybody has more then 1 device.

I would place 2 315 AP in one classroom. Having said that, I don't have all the details of the deployment so it is a guess.

Hi Frank,

 

You're right, redudancy is not planned.

In the classroom there will also have RJ45 and switch if needed.

I guess they will also have a spare AP to use when one is failing (one offline spare, just an AP on a shelf to take if needed).

This is not critical.

Also you're totally right, a student can have a smartphone, a tablet or so !

And we do not want that... we'd like only laptop for citrix use.

This is something i do not know how to manage.

 

Yes 2 AP seems the best thing, this is something we thought about but imagine :

 - they are many classrooms that will be side by side, size should be something like 5mx8m

 - if i put 2 AP, density of AP will be too important and we won't have enought channel, no ?

 

attached is a little drawing, not representing the reality, but giving a good idea of it.

Imagine 15 rooms of 5mx8m, if i put 2 AP per classroom (green circles) density seem to high, no ?

 

All your advices are welcome

Thanks a lot

 

 

What are your walls made of?

Do you have existing wireless?

Depending on how mission critical your deployment is, redundancy might just be a spare AP that you would deploy.

A student could have a smartphone and a tablet, but they would probably only be using one at a time, so 2 APs/classroom would be too high.

With regards to channels, if you turn on DFS, you would have 22 802.11a channels available, and depending on what your walls are made of and the transmit power, your APs might not go more than two classrooms down the hall.  The 2.4gz band you could tune lower so that it also does not go far.

 

That is a simple diagram, but you would probably need a mini-survey to determine how far your signal goes and what you should put where.

 

Please see the 802.11n(applies to 802.11ac as well) Survey VRD here: http://community.arubanetworks.com/t5/Validated-Reference-Design/Indoor-802-11n-Site-Survey-and-Planning/ta-p/155136 to get some ideas on what you could do..

Thanks Colin,

 

this is a simple but very good idea to have 2 AP with lower range !!!

You're right channel congestion will be then reduced...

 

I just do not understand this sentence "With regards to channels, if you turn on DFS, you would have 22 802.11a channels available"

 

regards

Please see here:  http://community.arubanetworks.com/t5/Controller-Based-WLANs/What-is-Dynamic-Frequency-Selection-DFS-How-to-Enable-it-What/ta-p/179170

Really interesting

But here, we are near military facility :)

But sure i can try that.

 

By the way you gave me many things to think about and many thanks for that

Even without enabling DFS, you have 9 802.11a channels if you use 20-mhz wide channels...