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Performing Hitless Software Upgrade on Data Center Devices


Perform the following steps to upgrade the software image on the devices in a data center fabric with no loss of user traffic.

To perform hitless software upgrade on data center devices.

  1. Upload the software images to which you want to upgrade your devices.
    1. Navigate to the Infrastructure > Fabrics page in Contrail Command. A list of fabrics is displayed in the Fabrics tab.

    2. Click the Upload button in the Images tab. The Upload Image page appears.

    3. Enter the required software image details and click Upload. Table 1 lists all the mandatory parameters that must be entered to upload a software image.

      Table 1: Upload Image Fields



      Enter a name for the software Image. This name cannot be changed once the image has been uploaded.

      Pick a File

      Select the actual image file to be uploaded.

      Vendor name

      Enter the image vendor name. For example, Juniper, Arista, and so on.

      Device Family

      Enter the device family. For example, junos, junos-qfx, and so on.

      Supported Platforms

      Enter all the device platforms that the image is compatible on.

      Os Version

      Enter the OS version of the image. For example, 18.1R2.

    4. Upon successful image upload, the Images tab appears listing the newly uploaded software image. Apart from the image name, you can edit image details at any time.

      The same list of device images is available for image upgrade in 3.

  2. Click the Fabrics tab and select a data center fabric.

    The list of devices connected in a spine and leaf topology and corresponding details of each device in the selected fabric is displayed. The roles assigned to the devices are also displayed.

  3. Click Action > Image Upgrade. The Select Device page appears. The list of images available to be upgraded to is displayed.
  4. Select the image and the compatible devices to be upgraded to that image in the Assign Devices tab.

    You can select one or more devices in the fabric. You can also select multiple images.

    Figure 1: Select Device > Assign Devices
    Select Device > Assign Devices
  5. Select the health check parameters for each device in the Parameters tab.

    The health check parameters confirm that the devices and the network as a whole are stable to perform hitless image upgrade. By default, if health check fails for a particular device, then image upgrade is aborted. You can deselect the Abort on health check failure check box to continue upgrade on a device even if the health check fails.

    Figure 2: Select Device > Parameters
    Select Device > Parameters
  6. Click Next. The Testing page appears.

    The Test Run tab checks that the devices selected for upgrade are not already running the selected software version. The Test Run tab also displays the result of the health check on the devices for the parameters selected previously in the Parameters tab. If health check fails for the selected parameters, then you can go back to the previous page by clicking Previous and either changing the value of the health check parameter or disabling the parameter altogether. You can perform this step multiple times until health check passes for the device or you are able to determine that upgrade on the devices is feasible. Alternatively, you can click Previous and deselect the Abort on health check failure check box in the Parameters tab to continue upgrade on a device even if health check fails.

    Figure 3: Testing > Test Run
    Testing > Test Run
  7. Click the Strategy Plan tab. The Strategy Plan tab displays the strategy used to upgrade the images on the selected devices. Image upgrades occurs in batches, where multiple devices are upgraded at one go. The default maximum size of a batch is four devices.

    The leafs are upgraded first and in a separate batch from their corresponding spines. If multihoming is configured on a BMS, the corresponding devices are upgraded in different batches. The batches are formed so as to have backup devices in a separate batch to the devices being upgraded in order to make the upgrade hitless. You can view the summary of the strategy used to upgrade the devices at the top and you can scroll down to view complete details of the devices. The estimated time for image upgrade per batch is also displayed.

    Figure 4: Testing > Strategy Plan
    Testing > Strategy Plan
  8. Click Next. A confirmation page requesting confirmation of the image upgrade process is displayed.
  9. Click Yes to confirm that you want to continue with the image upgrade. The Upgrade page appears displaying the status of the image upgrade progress for each device. The cumulative list of devices is displayed and the upgrade process happens according the batches determined in the strategy plan. The overall progress of all the devices is also displayed.

    Alternatively, click No to go back to the previous page.

    Figure 5: Testing > Strategy Plan Confirmation
    Testing > Strategy Plan Confirmation
  10. Click on each device to view the image upgrade progress for that device. Click the device again to toggle back to display the overall image upgrade progress of all devices. Table 2 displays the states displayed during the course of the upgrade.

    Table 2: Image Upgrade Progress States




    The devices are prepping for the upgrade by running health checks.

    Health Check Failed

    Health check on the device has failed. You can click Previous and go back the Parameters page to either change the health check parameter value or disable the parameter.

    Activating Maintenance Mode

    The device has passed health check and the device is being placed under maintenance mode.

    Deactivating Maintenance Mode

    Removing maintenance mode configuration from device and exiting maintenance mode.

    Maintenance Mode Activated

    Maintenance mode is active on the device.

    Maintenance Mode Deactivated

    Deactivating maintenance mode is complete and maintenance mode configuration is successfully removed from the device.

    Maintenance Mode Failure

    Internal error detected during maintenance mode activation or deactivation.

    Hitless Image Upgrade Successful

    Device image is successfully upgraded.

    Hitless Image Upgrade Failed

    Device image is not upgraded.


    Attempted to upgrade to the same image version or the device family does not support hitless upgrade.

    Figure 6: Upgrade
  11. Click Finish when all the devices have been upgraded.

    Alternatively, to cancel the upgrade process, click Cancel. The Infrastructure > Fabrics page is displayed.


You can re-enter the upgrade workflow if you exit at any point in the process. Also, in case of any failure, the reason is available in the device logs.