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We can use TFTP, FTP or HTTP/HTTPS any kind of server to communicate and to fetch the firmware.
Autoexec
Vega has feature called "Auto Execution" aka "Autoexec" which will allows a Vega to automatically upgrade its firmware and configuration on power up and reboot.
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Script is downloaded as a file from any of the configured server (e.g tftp, ftp, http or https) and executed.
Autoexec Configuration
1) Configure Server -
GUI→LAN/Wan section - specify the file transfer method.
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Above will download the <vega-firmware-name> firmware if its different then existing and then will download "config2.txt" file.
Reference
"Autoexec Script" section in Vega Admin Guide.