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Advice on downgrade JunOS 15 to 12 on EX3300

  • 1.  Advice on downgrade JunOS 15 to 12 on EX3300

    Posted 01-13-2023 07:18
    Hi All,

    I have an EX3300 that has been running various JunOS versions, the previous one has been some 12 version then I upgraded it lately to 15.1R7-S7.1, the latest version I can get my hands on. Now it appears the rumours are true and the 15 series isn't that great for EX3300 switches. I hit one major bug where you include a tagged subinterface (e.g. ge-0/0/17.17, not a vlan interface) in a routing-instance and everything goes bottom up. The switch crashes so hard that it's config gets corrupted and it looks like various other stuff too, so best to zeroize after this point. It also appears to be reproducible (so I spent quite some time getting my switch up and running each time).

    I'd like  to avoid this in the future, so I want to downgrade to a current recommended version, which seems to be a 12 or 13 series version. I used one of the images I have available to me, which is 12.3R12.4 and seems to be a fairly up to date 12 version.

    I tried this on another switch. Installed 15.1R7-S7.1, then downgrade to 12.3R12.4. No problem there.

    Then I did my "production" switch this morning and it didn't go well. Whatever I did, the switch insisted on going into a state where the switch was "linecard" mode, "fpc0 is not found", "please login into the master unit" etc etc.  "show vc" says the unit is actually master (and no other unit is present or known).

    These actions did not work:
    - zeroize
    - request reactivate vc
    - remove files under /config/vc (+ reboot)
    - remove vc statements in config (they're not there anyway, it's a standalone switch)
    - reinstall JunOS

    As a last resort I reinstalled 15.1R7-S7.1 again and then it worked again. But that is not what I want. Can anyone give me a good advice on how to downgrade JunOS from 15 to 12 or 13? Are there special precautions to be taken? Would it help to install JunOS from the boot loader prompt? I don't care whether everything is removed/lost/cleared, I can copy the config from USB stick and I don't need anything else.

    These are the images I have available, advice on which to use? How about the 13.2 series?



    Erik Slagter