How many connections?

Unanswered Question
May 31st, 2008

Just a quick planning question. This is a church environment that may grow quickly. They're currently trialing with three LinkSys devices and about 25 users. But they anticipate up to a couple of hundred users if successful. Which device(s) would be best for lots of connections? And how many would that be per access point?

I have this problem too.
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scottmac Sat, 05/31/2008 - 12:44

The absolute answer is "It Depends" ... just like any other size or implementation question.

For commercial APs from Cisco, the closest thing to "rule of thumb" is ~20 concurrent users per AP, but that number can be adjusted up or down depending on the application, protocols in-use, and overall volume of traffic per user. Also keep in mind that ONE USER radiating an 802.11b signal into your coverage will (may) slow down the system and reduce the potential max count.

I would also humbly suggest you dump the Linksys and go with commercial APs, as they will have more options for fine tuning the power, coverage, rogue mitigation, monitoring, and control.

How many do you need? From the information provided, I'd say 500 or so. You can probably adjust that down somewhat according to the size of the coverage area, building materials, and a mess of other parameters ... without that info, I'll go safe and say 500 ( ;-} .

i.e., How many vehicles do I need to transport the entire senior class of my nephew's high school class at one time? We need to create a solid transportation budget.

Realistically, what you need is a solid site survey that will measure a real signal in the actual environment with real or simulated traffic that is comparable to the expected loads. There is no substitute.

If you are not prepared to do that kind of survey, you should hire someone to come in and do it for you, as this is *critical* information and can save you a mess of money (frustration, reputation) in the long run.

The site survey is where the budget meets head-on with the requested functionality. If you already have a budget planned, then expect to lose some functionality or coverage.

If you already have desires and expectations, then the site survey will provide you the information needed to come up with a reasonable and realistic budget.

As a final note: Just kidding on 500 (in case your sense of humor was broken). A proper spread of APs with the proper antennas can accommodate almost anything ... proper antennas for the coverage area is critical, and selection of same is a big part of the site survey.

Good Luck

Scott

JohnMeggers Sat, 05/31/2008 - 14:01

Hi Scott,

Thanks for the quick reply. Yeah, they have no intention of keeping the LinkSys devices. No argument there. But since we need 500 of them, we may need to move to D-Link to save money . . . ;-)

Actually, the trial is more for whether they even want wireless in a worship service than for coverage. These devices are in the worship area and one device can cover the whole room.

We put three in because they were cheap and so we could we could hopefully distribute more users over the three non-overlapping channels. I was guessing 20-25 users per device, so no surprises there either. But I was hoping the "bigger iron" might have afforded more users.

It looks like more devices, tweaking power levels and various "B only" and "G only" configurations may be the way to go to get a lot of users up in one room. Unless there is something else out there I'm not aware of.

I've done a fair amount of wireless in the manufacturing environment, but never at this user density. Kind of groping here.

If anyone else has any suggestions, I'd love to hear them!

Thanks,

John

Naveen Kumar Tue, 04/09/2013 - 13:32

Hello,

You can  put three, because they were cheap and so we could we could  hopefully distribute more users over the three non-overlapping channels.  I was  guessing 20-25 users per device, so no surprises there either.  But I was hoping  the "bigger iron" might have afforded more users.

It looks like more devices, tweaking power levels and various "B only" and "G  only" configurations may be the way to go to get a lot of users up in one room.   Unless there is something else out there I'm not aware of.

Leo Laohoo Tue, 04/09/2013 - 14:47

I'm no expert on the LinkSys product, but in the Aironet series AP, Cisco recommends 25 clients per AP.

HOWEVER, this will depend on what kind of data traffic and your ethernet/ethernet backbone is like.

For example, if your clients will be doing alot of emails, chatting or HTML stuff then the number grows to about 35 clients per AP.  But if you're talking about video streaming then the ideal client-to-AP ratio falls down to about 8 clients per AP.

There are also alot of factors which determines if your client can get full speed or not.

Factors such as:  radio protocols clients are working on, what kind of clients, channel interferrence if clients are operating only at 802.11b radio protocols, what kind of ethernet link is used from the AP to the switch/router, what kind of ethernet backbone is being used from the switch to the internet, etc.

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