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  1. #1

    Exclamation ethtool showing link detected when no link present

    Hello all,

    I have an SFP ethernet interface which ethtool shows as having a link detected = yes, when there isn't actually any cable present - see output below:

    Settings for eth6:
    Supported ports: [ FIBRE ]
    Supported link modes: 1000baseT/Full
    Supports auto-negotiation: Yes
    Advertised link modes: 1000baseT/Full
    Advertised auto-negotiation: Yes
    Speed: 1000Mb/s
    Duplex: Full
    Port: FIBRE
    PHYAD: 0
    Transceiver: internal
    Auto-negotiation: on
    Supports Wake-on: umbg
    Wake-on: d
    Current message level: 0x00000007 (7)
    Link detected: yes

    Now, the problem is consistent between reboots. I can correct the problem by doing an ifconfig down and then ifconfig up, but this this doesn't sit easy with me. I'd like to find out why the issue occurs in the first place as I think it may be related to an issue where I saw all 16 interfaces fail to come up with the exception of just eth6, the interface I'm experiencing the problem on! The issue occurs regardless of whether there is a fibre transceiver inserted. Furthermore, the issue occurs on multiple identical machines I'm running on, again all consistently showing the problem.

    The only hint I currently have on the problem is the following line in syslog:

    e1000: eth6: e1000_watchdog_task: NIC Link is Up 1000 Mbps Full Duplex

    and there's no other occurrence of this line for any other interface in the syslog.

    lspci shows the driver to be:

    07:00.0 Ethernet controller: Intel Corporation 82571EB Gigabit Ethernet Controller (rev 06)

    And I'm running kernel 2.6.17

    Any light is greatly appreciated!
    Last edited by johndunne; 06-12-2009 at 07:48 AM. Reason: another typo, preview used this time!

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