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Centralized vs Distributed Data forwarding. Centralized vs Distributed WLAN architectures. SCA vs MCA.

What specific situations have you used one over the other?
Who would you say the vendor leaders are in each category?
What is the future for the normal office environment?
Should there be a full controller or only management system?
If controller is used what features of the MAC would you say ?should? stay at the AP?

Personally, I think the centralized controller model will slowly dissapear.

Really? What makes you say that?

I believe you are right. A lot of people believe the full controller is not needed but most agree the management system portion of the controller must stay. This might be in a standalone system or maybe in MASTER AP.

Who do you think provides the best solution for a controllerless WLAN?

Sean, your question brewed a vendor battle last time. In my opinion, most vendors are moving towards distributed architecture. How you define centralized vs distributed may be tricky. For example, if an organization moved multiple central controllers from the core into the edge and communicated with each other, does that still make it distributed or centralized?

I think it depends on customer use case... Disclaimer: I work for Aruba as a product marketing manager. Spent last 7 years here at Aruba so my views will be biased to some extent!

1. Use standalone fat APs if your deployment is not more than 1-2 APs, 5-6 different locations. You can get by. Vendors: Ruckus, Cisco fat APs and every other vendor on the planet.
2. Go smart APs for small scale deployments with basic roaming, 11n performance, guest access requirements. Vendors: Aruba Instant, Aerohive, Meraki.
3. Go centrally managed remote AP deployments if you need to extend central security policies to remote sites. Vendors: Aruba VBN, Cisco OfficeExtend + ISR, Aerohive.
4. Go physical controller based thin AP deployments for large (100+) AP deployments in a single campus. Context based policies for BYOD, centralized security policies and VLANs, centralized encryption + authentication + firewall for secret level security, application awareness in WLAN for multi-app per device support, always-on spectrum analysis, advanced WIPS, wired and wireless management. Vendors: Aruba, Cisco

There are probably 1.5, 2.5, 3.5 in between these scenarios where all of these vendors seem to play. I think all of fat APs, intelligent APs, virtual controller APs, remote APs, physical controller-based thin APs will continue to live... and customer requirements will dictate which gets deployed where.

Thanks for the comments. I believe you are right. We must always design/deploy for user case.

Ozerdo's comments pretty much match my thoughts, but I believe scenario #4 will still eventually turn away from centralized controllers.

I see a vendor war in 5..4..3..2..1.

Hahaha

Then let the vendor war begin! Ubiquiti and their disruptive pricing for the win! [;-0))

Seriously though, I'd say the hybrid architecture will win out, mostly due to 802.11n. It needs to be distributed due to the centralized bottleneck problem yet you want to maintain some sort of centralized management and reporting.