We have a 2003 Certificate Server. We wish to add a Windows 2012 Certificate Server to the same domain but preserve the Windows 2003 server for old existing certificates that are not compatible with the new 2012 features. The 2003 will no longer be able to push out new certificates, only the 2012 server will be able to do this. Each server has a separate rootCA so they are independent of each other. The long term goal will be to retire the 2003 server when we get all the XP machines out.
Is it necessary to create a Cross Certification cert for the 2003 and 2012 servers to talk to each other? Since the 2003 server will be not doing anything but servicing existing certs, is the Cross Certificate necessary?