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All, 

I've been studying for the CWNA (105) for a couple months, and hope to take it before the 106 change over. One thing I cannot seem to figure out, is with a multiple channel architecture, is there really is any "smart" roaming. In the book, it clearly states that the decision to roam is done by the client station (i.e. laptop). However, with Controller based (physical or cloud) many vendors say, that they help clients roam to a better access point. Is this total B.S. by vendors or is there a real way for a 'smart way' to move stations to a different access point?  If there is a smart way, how does it really work?

Lets say my laptop is connected to AP1, but in reality, I should be connected to AP2-- however the laptops client drivers / program, think AP1 is at least "good enough". Does a controller based MCA, somehow send a re-association frame from AP2 to the laptop?  Does the controller (or AP1) send a disassociation frame to the laptop, and essentially 'block' my laptop from re-associating to AP1, to force it to "roam" to AP2?

Not every device keeps a list of every AP it has seen, so it might be possible for controllers to limit which AP would respond to a probe request.     But that would probably result in some slow roaming.

Unless I am forgetting something, any device can issue a disassociate, but re-associate commands are only generated by clients.

Yes, many vendors do have that kinda solution to force clients to roam and they are based on Controller Algorithm.

You are absolutely right in context of roaming. It's clients who decide, but there's something called 'Sticky Clients' who generally don't roam well. So some vendors enable this feature, forcing clients to roam, rather than just depending on clients understanding of channel state.

Hope this helps.