I have to change a switch within a fabric. This fabric contains some different (brocade and brocade OEM) switches with 6.x FOS. Do I have to downgrade the new switch or upgrade the others to FOS 7.x or do they work togeter in mixed mode?
FOS release Compatibility are listed in release note.
Some FOS 6.x release are compatible with FOS 7.x some not.
Compatible, Approved and Supported different FOS can work in same fabric without any restriction.
about Upgrade from 6.x to 7.x depend on Switch Models, i.e. 4G Plattforms cannot be upgrade to FOS 7.x