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    Understanding Download Manager for SRX Series Devices

    This topic includes the following sections:

    Overview

    This download manager feature facilitates download of large files over low-bandwidth links. It enables you to download large Junos OS packages over low-bandwidth/flaky links so that the system can be upgraded. This feature allows you to download multiple files while monitoring their status and progress individually. It takes automatic action when required and displays status information when requested.

    This feature is supported on SRX300, SRX320, SRX340, and SRX345 devices.

    This feature provides the following functions:

    • Bandwidth-limited downloads

    • Scheduled downloads

    • Automatic resume on error

    • Automatic resume on reboot

    Note: This feature supports only the FTP and HTTP protocols.

    Using Download Manager to Upgrade Junos OS

    The download manager acts as a substitute for the FTP utility. You can use the download manager CLI commands for all the functions where you previously used the FTP utility.

    The download manager requires the following:

    • FTP or HTTP server with a Junos OS image

    • Server that is reachable from the device being upgraded

    The download manager consists of the following CLI commands:

    1. To download the Junos OS image to your device, use the request system download start command (set a bandwidth limit, if required). The file is saved to the /var/tmp directory on your device.

      You can continue to use the device while the download runs in the background.

    2. Use the show system download command to verify that the file has been downloaded. The command displays the state as "completed" when the downloaded file is ready to be installed.
    3. Use the request system software add command to install the downloaded image file from the /var/tmp directory.

    Handling Errors

    If you encounter any problem with a download, use the show system download id command to obtain details about the download.

    Table 1 lists the output fields for the show system download command. Use this information to diagnose problems. Output fields are listed in the approximate order in which they appear.

    Table 1: show system download Output Fields

    Output Field

    Description

    Status

    State of the download.

    Creation Time

    Time the start command was issued.

    Scheduled Time

    Time the download was scheduled to start.

    Start Time

    Time the download actually started (if it has already started).

    Retry Time

    Time for next retry (if the download is in the error state).

    Error Count

    Number of times an error was encountered by this download.

    Retries Left

    Number of times the system will retry the download automatically before stopping.

    Most Recent Error

    Message indicating the cause of the most recent error.

    Considerations

    • When no download limit is specified for a specific download or for all downloads, a download uses all available network bandwidth.

    • Because the download limit that you set indicates an average bandwidth limit, it is possible that certain bursts might exceed the specified limit.

    • When a download from an HTTP server fails, the server returns an HTML page. Occasionally, the error page is not recognized as an error page and is downloaded in place of the Junos image file.

    • Remote server logins and passwords are stored by the download manager for the duration of a download. To encrypt these credentials provided along with the login keyword, define an encryption key with the request system set-encryption-key command. Any changes to encryption settings while download is in progress can cause the download to fail.

    • A download command issued on a particular node in a chassis cluster takes place only on that node and is not propagated to the other nodes in the cluster. Downloads on different nodes are completely independent of each other. In the event of a failover, a download continues only if the server remains reachable from the node from which the command was issued. If the server is no longer reachable on that node, the download stops and returns an error.

    Modified: 2017-08-31