As part of an ISSU, soft reset is supported even if the (old) firmware version on the MDAs is not the same as the (new) firmware version in the software load to which the user is upgrading. The soft reset is allowed to proceed by leaving the previous version of the firmware running while upgrading the rest of the MDA/IOM/IMM. The user can then issue a hard reset of the MDA/IMM at some time in the future to upgrade the firmware.
The soft reset is only allowed to proceed if the older firmware is compatible with the new IOM/IMM software load. Otherwise the soft reset is blocked and a hard reset must be used instead.
After a soft reset has been completed, a log event is raised to warn the user that the MDA (or IMM) is running older firmware and that they can perform a hard reset of the MDA (or IMM) at some point if required.
If the MDA/IMM is not hard reset by the user, and then a software upgrade is performed, and the older firmware is no longer compatible with the newest load being upgraded to, then the soft reset is blocked (or an automatic hard reset occurs for ISSU).
The user can see whether they are running with older MDA/IMM firmware at any time by using the show mda detail command.