Overview of Upgrade Maintenance

Upgrade maintenance is performed on a single device and can improve device reliability by upgrading the device's system software, installing a patch file, and updating the GTL.

If the current software performance does not meet requirements, you can upgrade the system software, install a patch file, or update the GTL to allow the device to work properly on the network. Table 1 describes three means of upgrade maintenance: software upgrade, patch installation, and GTL update.

**Table 1** Description of software upgrade, patch installation, and GTL update
Means of Upgrade Maintenance	Description	Remarks
Software upgrade	System software upgrade can optimize device performance, add new features, and upgrade the current software version.	The following types of software upgrade are supported: Software upgrade that takes effect at the next startup The system software is suffixed with .cc.
Patch installation	Patches are a type of software compatible with system software. They are used to fix urgent bugs in system software. You can upgrade the system by installing patches, without having to upgrade the system software.	The following types of patches can be installed: Hot patches: They are installed on non-stop-working devices without interrupting services. Cold patches: They are installed on devices that do not need to work uninterruptedly for a long time. The installed patches on a device take effect after the device is restarted. A patch file is suffixed with .PAT.
GTL update	A GTL file controls all resource and function items that can be used by a device. All service features that have been configured on devices can be enabled only when a GTL file is obtained from Huawei. GTL file update does not require software upgrade or affect existing services.	After the GTL has been updated, the GTL-controlled service features can be used without restarting the device. A GTL file is suffixed with .dat.

Before performing upgrade maintenance, note the following points:

Refer to the Version Upgrade Instructions released by Huawei when performing system software upgrade.
Enable the log function to record all upgrade operations. This will help you locate and analyze the fault in case of an upgrade failure. For details on log functions, see Information Management.