Hi Kyawswar,
The .tgz format is the standard format of JunOS image which you can find at the website:
https://support.juniper.net/support/downloads/
There are a couple of formats for JunOS packages, you might want to give this a read while you sip some coffee:
https://www.juniper.net/documentation/en_US/junos/topics/topic-map/software-install-and-upgrade-overview.html#id-junos-os-installation-package-names
However, the .gz format is called install-media format, this image can be used for upgrade of the device via bootable USB:
By default, this is the boot-sequence for an MX device:
USB, compact-flash, disk, lan
So, now take a USB(atleast 4GB) make it a bootable one(third party app "rufus" can be used to make the USB a bootable one and load the image file) does the job; once it is ready follow the below:
[Refer kb https://kb.juniper.net/InfoCenter/index?page=content&id=KB27369 ]
- Connect to the router console port. This is critical for the Install Media to work on an MX device.
- Insert the USB drive into the USB port of the router and reboot or power on.
This should get you on the new image...
Please hit kudos if that helped, mark "accept as solution" so other users with similar queries are directed here without them having to repost 🙂
Thanks & Regards,
Nex