WiSM Cluster?

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Mar 9th, 2010
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I have read that WiSM supports 12 modules in a cluster for a total of 3,600 AP in a mobility domain. In some other sources I read that it can cluster up to 7,200 APs. What is the real number of APs it can cluster in a mobility domain?. How many can it cluster in a mobility group?


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weterry Tue, 03/09/2010 - 22:26
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I think you've been reading the CCNA Wireless book....

My understanding is that you can officially have 24 controllers in one Mobility Group. But you can have 72 Controllers in a Mobility Domain.

So as each WLC in a wism support 150 APs (12 wisms = 24 wlcs), I'd have to go with 3600 in a Mobility Group and 10800 in a Mobility Domain.....  At least doing the math, that is what I come up with.

My best guess is that they wrote it to mean 12 wisms (24 WLCs) at 150 each = 3600, then someone had the bright idea that you take 3600 and multiple by 2 (2 wlcs in a wism) and get 7200....  fuzzy logic but it was the only thing I could think of to get 7200....

But again, we are talking about a Mobility Group here, not a Mobility Domain.....

now.. the WISM product sheet like the number 7200 as well for number of APs in a roaming domain.... so I guess I honestly don't know where that number comes from...  Maybe the mobility logic just can't keep up with more than 7200 APs...

For example, if you had 72 4404-100's in your Mobility Domain, you'd have 7200 APs maximum....

So I guess the real question here is whether it is 7200 hardset, or if the 7200 was based on someone calculating 72 X 4404-100 before the wism was out?

fjcardenas-1 Wed, 03/10/2010 - 06:55
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Sorry but I am still not clear and now I have more questions.

1.- Cisco book says each WiSM blade has 2 controllers and each controller can handle up to 150 APs (that is 300 APs per blade). Then it says that you can cluster 12 of them into a mobility DOMAIN and this allows up to 7200 APs in a mobility domain. In the Cisco web page I found information for the WiSM that says that you can have up to 7200 APs in roaming domain.................. Where do they get the 7200 if you can only get 3600 doing the math (12 blades x 2 controllers per blade x 150 APs per controller)?

2.- What is it that you cluster..... controllers or blades?

3.- If you cluster controllers... does it matters how many APs the controllers habdle?

4.- I also read that you can have up to 24 controllers in a mobility GROUP..... Does it matters how many APs they can handle? Can it be 24 controllers where each one handles 150 APs (like the WiSM) or 24 controllers where each one handles 6 APs (like the 2106 WLC)?

skronawithleitner Wed, 04/28/2010 - 22:58
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oh, that again :-)

that is a confusing subject.

the limit of a mobility group is 24 controllers, 3600 APs. (which is of course, 12 WiSMs - 12 x 300 or 24 x 150)

the limit of the possibility to roam is since code 5.1 roaming across 72 controllers, which makes 3 mobility groups (it is possible to roam between mobility groups then) - that should make 10800 APs to roam with WiSMs (150  x  72  or 3600  x  3)

with a 4404 that 2 numbers would add up to 2400 APs (24 x 100) in a mobility group and 7200 APs (100 x 72  or  2400 x 3) to roam.

so we got both numbers straight.

now the 5508 supports 250 APs per controller, which would make with 24 controllers 6000 APs in a mobility group and with 3 of those 18.000 APs to roam, which corresponds to the official numbers of the 5508 controller in a PDF from cisco networkers. ("18,000 APs in Mobility Domain").

note that there is also some confusion about the terms "mobility group" and "mobility domain". some state they are the same, some state that a mobility domain are those 3 mobility groups to roam in. since both terms are used everywhere, i'm not sure whats the official cisco deal :-)

edit: oh, i found this great post on the group/domain/list subject: http://wirelessccie.blogspot.com/2009/12/mobility-group-list-domain.html

very interesting how this developed. so the 72 controllers are in a "mobility list", and "group" and "domain" are the same.

m-fletcher Wed, 04/28/2010 - 23:34
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Ha.. Yep.. That last response is so spot on.

I didn't add that but the dilemma to know is that the CCNA Wireless exam seems to state that questions are based on the "version 5" WLC revision level.

I only hope they are referring to V5.0 and not 5.1+.

Hopefully I won't get this type of question on this because the answer varies!!


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