I am writing you because between a mounth i have to migrate 2 CISCO WLC 4400 Series.
My problem is the firmware, infact the 2 devices have a dofferent firmware installed. At the moment they are in to different location, but after the migration, they are into the same and i'd like to configure them using the Mobility option and i don't think it is possible if the 2 devices have a different firmware working.
As second i'd like to have some gude about the static mobility, so that i can configure the 2 WLC as in a cluster and i can have a redundancy in my wireless lan.
Im looking foward about your answer and i hope they arrive as soon as possible.
You are exactly right! If both of your WLCs are going to be a member of the same Mobility Domain, you must be running the same version of WLC code. Here is a great link that explains the requirements to deploying a mobility domain along with how to add the mobility members to each WLC:
Deploying Cisco 440X Series Wireless LAN Controllers - Mobility Group Requirements