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  • 1.  SFP Up, But Link Down After Reboot

    Posted 01-21-2022 18:34
    Working with an EX-4600.   Upon inserting an SFP into this switch and fiber into the SFP, all is working as it should.
    However, when I do a reboot of the switch, the link does not come back up.
    The interface does show in "show interfaces" after the reboot on both the switch and the remote side, however, neither disabling and re-enabling the port nor doing a soft reset of the SFP works to restore it.  The only thing that makes it work again is if I physically unplug and replug the SFP.

    Does anyone have any insights as to what may be the solution here?
    Thank you.

  • 2.  RE: SFP Up, But Link Down After Reboot

    Posted 01-22-2022 05:45
    I should clarify, that both the interface and link are reporting UP when running "show interface terse" command.

  • 3.  RE: SFP Up, But Link Down After Reboot

    Posted 01-22-2022 05:51
    Are you saying that the interface shows but admin and link up on both sides?

    Then what is the exact problem seen?  What does "down" mean for this problem you are troubleshooting?

    And then what is the configuration related to the feature that is down and not working?

    And how was it functioning before the reboot?

    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)

  • 4.  RE: SFP Up, But Link Down After Reboot

    Posted 01-23-2022 05:40
    Thanks, Steve.
    I figured this out last night.  Basically I had the irb.0 and em0.0 subnets the same and this seems to have caused the problem.  While there was nothing in the config check to warn me about this, I did find the warning in the startup section of the logs.  Once I changed the em.0 subnet, then the switch started working normally.  Although I still have to move all the patch cables from the backup switch and test.
    Using version 20.  It's odd that there wouldn't be any warning during a config check. and odd that this would be an issue even though there was nothing plugged into the em0 port.