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New Member

Getting started, clients per AP & scaling questions

Hi.

This is my first time into the wireless side. I need to scale a solution for a large campus. I have an idea of the number of APs required to cover the area, but I don't know how many end users can connect to a given AP, and presume there is some limit? I'm particularly interested in how to do this in auditoriums where it is a large open space, but with many delegates. So is there a general rule of thumb on "not more than x users per AP"? The plan is to have all APs linked together using a WLAN controller.

Other question: is there any functional difference between having dedicated 4402 / 4404 WLAN controllers and using a WISM service module in a Catalyst 6500 series switch?

Thanks in advance.

4 REPLIES
Silver

Re: Getting started, clients per AP & scaling questions

Hi Xavier,

Welcome to the world of wireless!

Cisco APs can support quite a few clients, but they recommend no more than 25 per AP. Lightweight controllers default to limiting it to 12 clients per AP, but this can be changed. For large auditoriums, you should decide how many users you want to support and install the appropriate number of APs. If you can keep it to 3 APs or less, that's best for interference. However, I run 4 APs in a large auditorium, and I don't have interference issues.

The only functional differences between the WiSM and standalones is the physical uplinks and the number of APs they can support. A 4404 is the largest controller you can buy, and it only supports 100 APs. The WiSM supports 300 APs. The WiSM also has backplane uplinks to the chassis switch, whereas 4400s rely on gig uplinks to the network.

If you have any other questions, please don't hesitate to ask!

Jeff

New Member

Re: Getting started, clients per AP & scaling questions

Thanks Jeff. That's exactly the kind of info I was after!

Regarding management of all the wireless side, am I right in believing that the WISM module in itself isn't sufficient and you really need the Wireless Control System software? I've had a look and see I can download Linux and Windows versions, but I don't know if this needs licensing and has an associated cost that I may not be aware of.

Because I'd be putting Catalyst 6500 switches in, my tendancy would be to go for the WISM module. Although it's a bit more expensive than the 4404 standalone, it does support more clients that I think we would ever need and I prefer the idea of it being "built in" to the core network.

Hall of Fame Super Gold

Re: Getting started, clients per AP & scaling questions

Hi Xavier,

I have an idea of the number of APs required to cover the area

How did you come to this "idea"? Did your business unit conduct a Wireless LAN Site Survey?

I don't know how many end users can connect to a given AP, and presume there is some limit

I am very surprised that as a first-time user you actually thought of considering this informatin. You have no idea how many people ignore this fact during the designing phase.

As the esteemed Jeff has mentioned, the 4400 comes in three "sizes", namely: 25, 50 or 100 APs it can manage. the WiSM is actually TWO 4400 and each can manage up to 150 AP's (bringing a total of 300 APs). In the next few months of this year, Cisco is rumoured to be releasing the "big Daddy" of standalone WLC that can control up to 500 APs.

Addressing the question about WCS, like the WLC, the license is based on the number of AP's too. In my humble opinion, if you have more than 2 WLC, then a WCS is a logical choice. If you want regular performance reporting of your WLAN networks then investing on a WCS makes sense too.

Hope this makes sense.

New Member

Re: Getting started, clients per AP & scaling questions

Hi Leolaohoo (cool name btw!)

The number of APs is/was an (un)educated guess. Having looked at the architectural drawings, I have an idea, but as I'm still in the process of discussing this with the customer, I have put a disclaimer in the number quoted, stating that the number may change and will be confirmed following a wireless site survey. But this is new territory for me, and I'm not too sure how best to do a site survey. Would this be something that I could do, with the correct equipment? Or is it best left contracted to some specialised wireless expert?

[i]"I am very surprised that as a first-time user you actually thought of considering this informatin. You have no idea how many people ignore this fact during the designing phase."[/i]

Thanks. Scaling and solution architecting is part of my job description and I thought there must be a limit. But appreciate that there's also a limit to the number of APs you can have in the same vicinity as they can interfere with each other.

Regarding your comment on WLC and WCS, am I right in believing there IS a licensing cost for WCS? Also, am I right in believing that you don't need WCS to set up a WLC, but it makes it a bit easier (like a nice web GUI instead of command lines on the WLC units)?

Also, if I were to have two WISM modules, one per Catalyst 6500 switch (in non VSS mode), I suppose they work as a main / backup ? In which case, how can they be synchronised? Is this a particular case where WCS helps as it oversees both units simultaneously?

Thanks for the help so far!

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