Cisco has introduced a new term called “new mobility” in their new “Converged Access” design for enterprise WLAN. Primarily this will change the protocol used for Mobility Tunnel between WLCs. In the current “Centralized Controller” design they used EoIP (Ethernet over IP) protocol for this and under latest “Converged Access” design they have changed this to CAPWAP.
CAPWAP has advantage as it can do fragmentation & re-assembly within protocol itself.
Why should I care about this today ? If your network have mixed of controllers models all of them need to talk to each other on same protocol (only option is CAPWAP as new controller only can do that). Unless your old controller configured for this “new mobility” you may encounter mobility issues if you are implementing new C3850 or CT5760 Wireless LAN controllers in your existing network (which consists of 5508, WiSM2, 2504).
Only option is you have to use WLC software code for existing controllers which support this new mobility feature. Sounds like not a big issue. But as at today this new mobility feature only supports on 7.3 MR1 release. So if you are operating any software code prior to that you can upgrade it to this & use this feature. But if you are already in 7.4 (like me 😦 ), yes you have to wait till Cisco release a new version to support this “new mobility” feature before bringing this 3850/5760 onto your network.
Another thing you need to understand is, this IOS based WLC software 8.x is only supports for new (Converged Access) CT5760 & 3850 controllers only. Cisco has no intention to bring these to existing controllers (5508, WiSM2, 2504). They will keep existing software train 7.x for these model until they retire these products.
Therefore interoperability between new WLC (3850/5760) & existing controller (5508/WiSM2/2504) will play a key role when designing wireless LAN solutions in coming days. If it is a green field deployment there should not be an issue of design it for “Converged Access” model.
Correction@27th July 2014
As you may already know AireOS 8.0 software code will be released in coming weeks. It is the next major software version for AireOS controllers (eg. 5508,2504, WiSM2,7500,8500). The information posted in my original post (dated 2013 March) was not accurate on this regard saying it will not suport AireOS controllers. In fact Cisco will not discontinue their CUWN product line for a foreseeable future. Converged Access products line (5760,3850,3650) will use IOS-XE releases where 3.6 is the latest as of today.
Thanks for @wirelessguru for highlighting this error.