We are upgrading Cognos Server from 10.1 to 10.2.1 , there is a store portal server on which Cognos GW(Web Tier) is installed which cannot be upgraded now. Can a Cognos GW (running on 10.1) connect to Cognos Dispatcher/CM running on 10.2.1 on a different server ?? Would the Cognos components(GW,CM) need to be on the same version level ? Can some please clarify ? Any help around this is much appreciated.
Mixing different versions of Cognos components is generally not supported. They should always all be on the same version.
Why not just have another server for a web tier for the mean time while the original server is not yet ready for upgrade. You can always repoint to the original GW once done with upgrade.