H3C Technologies H3C S12500 Series Switches - Manual (Page 140)

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Performing ISSU
ISSU applies to switches operating in IRF mode only. For more information about the IRF mode, see IRF
Configuration Guide.
Overview
In-Service Software Upgrade (ISSU) provides a fast way to upgrade an IRF fabric without or with the least
service interruption.
During an ISSU upgrade, you can perform version rollback and use specific display commands to view
information about version compatibility and upgrade status.
How ISSU works
You can upgrade an IRF fabric by using ISSU either on a per MPU basis or on a per member switch basis.
The upgrade principles and required upgrade procedures depend on the result of the ISSU version
compatibility check.
ISSU version compatibility check
The system software image that supports ISSU contains a version compatibility list, which records the
version of the system software image and the compatibility information of other software versions. At the
beginning of an ISSU upgrade process, the system automatically performs version compatibility check by
querying the version compatibility list. Version compatibility check results determine whether the ISSU
upgrade can proceed, the ISSU upgrade procedure, and the operations to be executed during the ISSU
upgrade process. Before the upgrade process, download the system software image, and then view
whether the current and new system software images are compatible with the display version
comp-matrix [ file upgrading-filename ] command.
The compatibility check result might be:
• Compatible—The fundamental modules that support the operation of the switch and the service
modules are compatible. The ISSU upgrade between the two versions can proceed successfully.
• Partially Compatible or Base-Level-Compatible—The fundamental modules that support the
operation of the switch are compatible, and some protocol modules are incompatible. The system
disables the incompatible modules automatically and the ISSU upgrade between the two versions
can proceed successfully.
• Incompatible—The fundamental modules that support the operation of the switch are incompatible.
In this case, you must provide the force keyword when you execute the issu load command, and the
interface cards can upgrade only through the reboot upgrade method.
• Unknown-Compatible—The queried version record is not in the version compatibility list. The
compatibility information between the system software image and the queried version is unknown.
The current system cannot be upgraded to the queried version through ISSU.