Blanketing a meeting area with Library Boxes?

[Stephen Jones]

Has anyone tried to blanket an area with multiple LBs? We have MR-3040 devices running v.2 and have tested 25 simultaneous connections at the most. Someone recently approached us about using 8 of them to distribute downloadable content to a conference of 150 people. Has anyone tried blanketing an area with multiple LBs using the same SSID and letting signal strength be the load balancer? My boss thinks it wouldn't work, but I'm not sure it wouldn't. In this case the user decided to go another route (which was probably better anyway) so I won't be testing it myself.

[Jason Griffey]

I have, and I've worked with a handful of orgs to do the same. Simultaneous connections is a tough nut on these tiny boxen....but having multiples in an area, whether the same SSID or slightly different ones (LB1, LB2, etc) does work to relieve the congestion on a single box.

Jason

On Tue, Jun 6, 2017 at 11:05 AM Stephen Jones <nph.help...@gmail.com> wrote:

Has anyone tried to blanket an area with multiple LBs? We have MR-3040 devices running v.2 and have tested 25 simultaneous connections at the most. Someone recently approached us about using 8 of them to distribute downloadable content to a conference of 150 people. Has anyone tried blanketing an area with multiple LBs using the same SSID and letting signal strength be the load balancer? My boss thinks it wouldn't work, but I'm not sure it wouldn't. In this case the user decided to go another route (which was probably better anyway) so I won't be testing it myself.

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[Matthias Strubel]

In Addition, consider using different wifi channels between the multiple LibraryBoxen .

That helps to distribute load on the shared medium "air"

Best regards Matthias 

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[Stephen Jones]

By "diff wifi channels" do you mean diff SSIDs?

[Stephen Jones]

Jason, how many boxes (boxen?) did you use at the same time and for how many users? Also, would you say that signal strength is the load balancer or what? Using multiple SSIDs would basically sidestep what I'm trying to do; there's no question that I could run 8 boxes and divide up the crowd the way I want.

[Stephen Jones]

And what exactly do you mean by it being a "tough nut?"
Thanks

[T Gillett]

Hi Stephen

I have been successfully using a similar set up in classrooms for a number of years. With a little care you can make it work quite well.

A few things to note:

1. There are only three wifi channels that are non-overlapping (ie do not interfere with each other) and these are Channel 1, 6 and 11.

If you use only these channels then there will be minimal interference and congestion.

2. Limit the Txpower to just what you need to adequately cover the area, there is no point blasting signal to the far reaches of the site where it will not be used. 

Limiting the power makes for less interference in the areas of overlap between access points.

For the TP Link devices like the MR-3040, the "txpower" setting in the radio section of the /etc/configwireless config file can be set to values between 0 and 18 and these values correspond prettty closely to the power in dBm delivered to the antenna. The default if txpower is not specified is to run at full power.

For classrooms I use a setting of 12 as a starting point.

3. Set the maximum number of simultaneous wifi connections that each access point will support. 

Commodity routers often don't have this parameter set, and the result is that the access point keeps accepting connections until it runs out of memory/cpu resources and starts dropping connections.

This is really frustrating for users, and particularly teachers in a classroom.

By setting a hard limit, you can guarantee that the router stays stable and when a client tries to connect it will be ignored by the access point in an orderly manner.

The setting for this is "maxassociations" in the AP section of the /etc/config/wireless file.

I have used a setting of 30 in classrooms and it is quite reliable, but YMMV as they say  :-)

4. It may better to use different SSIDs for each access point depending on your situation. 

It should work with the same SSID on all access points, but it seems that using the same SSID causes some (older?) wifi client devices to get confused.

In a multiple classroom situation, I have used the same base SSID string with just a different number on the end for each access point.

The down side of this approach if you are trying to cover one area with multiple access points (as distinct from using one access point in each adjacent classroom) is that users have to "roam" to find a free access point.

If you use the same SSID and set the maxassociations parameter on all the access points, then the wifi client will get a connection response from an access point that has free capacity, so you get a basic form of load balancing around the access points.  Don't forget that you also have to set the same encryption passphrase on all the access points in this case.

Hope this helps.

Regards

Terry

[Gaurav Saini]

Hello Terry,

I want to thanks for your detailed answer. I have a similar installation with multiple devices and your answers solved many of my doubts. 

Thanks again :)

Regards,

Gaurav

[Stephen Jones]

I guess I never got back to you, I'm sorry. Your detailed answer certainly deserves a reply and a thank you! This is very, very helpful and the details make it easy to implement.