WLC 7.4.100.60 and roaming problems on 8500

Question

Hello,
After installing an 8500 controller on 7.4.100.60 and migrating 1000 APs do this controller, we have the following problems:
[1] clients get disconnected and loose sessions (note: client is mobile gun and is heavily mobile). I have the impression there are more coverage holes. This might be due to bug CSCue13108, but says fixed in 7.4.100.60, we wil be upgrading to 7.4.110.0 anyway shortly.
[2] we have lots of L3 roaming problems between clients, especially when clients roam between old WISM controller and new 8500 controller. They don't roam, they get disconnected and reconnected, resulting in ip address change, resulting in sessions loss. Old controller still runs 7.0.230.0 but compatibility matrix says these two versions are L3 roaming compatible.
However, the release notes of 8500 mention this: "Cisco 8500 Series Controller cannot be configured  as a guest anchor controller. However, it can be configured as a foreign  controller to tunnel guest traffic to a guest anchor controller in a  DMZ"
Because Layer 3 roaming is similar to guest traffic tunneling, does this mean that the 8500 can be the initiator of a L3 roam tunnel, but cannot be the endpoint of a L3 roam tunnel ?
We have done a test that seems to confirm this: client starts on 8500 in state "local", goes to AP on old controller (7.0.230.0), but roam doesn't work. Client gets re-associated with ip address change. Then when moving back to the 8500 controller, the client does roam successfully, keeps its ip address in the 7.0.230.0 vlan and gets status "foreign" on 8500 controller. controllers are in same mobility group and mobility connections are all up.
In the 7.5 release notes, this limitation is not mentioned anymore. Does it mean it is solved and 8500 can be used as guest anchor controller in 7.5 ??
regards,
Geert

Answer 1

[2] we have lots of L3 roaming problems between clients, especially when clients roam between old WISM controller and new 8500 controller. They don't roam, they get disconnected and reconnected, resulting in ip address change, resulting in sessions loss. Old controller still runs 7.0.230.0 but compatibility matrix says these two versions are L3 roaming compatible.
Roaming from one AP to another that shares the same controller is totally different with inter-controller roaming, which you have now.  I believe WiSM-1 has 180 ms compared to the 90 ms on a 5508.  And this time difference means alot.
So when your client goes from one controller to another, they actually have to do a full re-authentication to the new controller.
I presume both the old and new controller are in the same Mobility Group?
However, the release notes of 8500 mention this: "Cisco 8500 Series Controller cannot be configured  as a guest anchor controller. However, it can be configured as a foreign  controller to tunnel guest traffic to a guest anchor controller in a  DMZ"
Pffft!  That'll be the most expensive Guest Anchor Controller if I follow this solution.