If a device crashes during an ISSU upgrade, the device will return to the initial state before the start of an ISSU operation.
During an ISSU upgrade, a single fault scenario is handled and system is restored to the original state. The double faults
may or may not restore the system back to the original state.
The system can be rolled back before a commit.A device can be rolled back to the initial stage by using the install abort issu command or after the expiry of the rollback timer before the install commit command is used. If the install commit command is used, no rollback is allowed. Rollback involves the following steps:
Provision and reset the standby RP
Provision and reset the active RP
If the roll back timer is not stopped by using the install
stop-timer command, the device rolls back to an older software version on expiry of the rollback timer. The default value of the rollback
timer is 120 minutes.
The rollback timer value can be set via the install activate location standby auto-abort-timer seconds command.