Ethernet link going down and then up after 3 seconds.



  • I have a server that shows the ethernet link going down and then up again. It is always around 3 seconds. In the log the first time it happened was 2 months ago. There are a total of 85 down/ups since then.

    What could be the cause for this? Could it be another device on the LAN? Why always 3 seconds?

    Excerpt from dmesg:

    [28468259.557902] igb: eth0 NIC Link is Down
    [28468262.617576] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [28468268.462849] igb: eth0 NIC Link is Down
    [28468271.522498] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [28468274.480760] igb: eth0 NIC Link is Down
    [28468277.452435] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [28468281.006518] igb: eth0 NIC Link is Down
    [28468283.958191] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [28470067.093744] igb: eth0 NIC Link is Down
    [28470070.033392] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX


  • @pete-s said in Ethernet link going down and then up after 3 seconds.:

    I have a server that shows the ethernet link going down and then up again. It is always around 3 seconds. In the log the first time it happened was 2 months ago. There are a total of 85 down/ups since then.

    What could be the cause for this? Could it be another device on the LAN? Why always 3 seconds?

    Excerpt from dmesg:

    [28468259.557902] igb: eth0 NIC Link is Down
    [28468262.617576] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [28468268.462849] igb: eth0 NIC Link is Down
    [28468271.522498] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [28468274.480760] igb: eth0 NIC Link is Down
    [28468277.452435] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [28468281.006518] igb: eth0 NIC Link is Down
    [28468283.958191] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [28470067.093744] igb: eth0 NIC Link is Down
    [28470070.033392] igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    

    Does this happen every 3 seconds all day every day, or is it random?



  • @dafyre Random in bursts. 85 times total in the last two months.



  • What services are on this?
    What does the switch it is connected to tell you?



  • any L2 managed switch with spanning tree?



  • @momurda said in Ethernet link going down and then up after 3 seconds.:

    What services are on this?
    What does the switch it is connected to tell you?

    It's a file server. No disruption in service has been noticed.

    The switch is one of the HP procurve smart-switches. Can't remember what model but it's gigabit. I don't know what kind of logging it has, if any.



  • @pete-s said in Ethernet link going down and then up after 3 seconds.:

    @momurda said in Ethernet link going down and then up after 3 seconds.:

    What services are on this?
    What does the switch it is connected to tell you?

    It's a file server. No disruption in service has been noticed.

    The switch is one of the HP procurve smart-switches. Can't remember what model but it's gigabit. I don't know what kind of logging it has, if any.

    In my experience spanning tree on managed switches can cause random "holes". If it is a procurve 2xxx or higher it should have a console with a log command. A handy one able to filter warnings and so.
    Would be interesting to log into the switch and check the file server port.



  • Like @matteo-nunziati says, see if STP is turned on on your ProCurve. If it detects a MAC on two interfaces, it will shut one down. Then it doesn't see it, so it turns it back on. I had issues at one time with a Wireless controller (Nortel) that had proxy arp on that would cause a segment of the network (the switch the wireless AP was on) to get shutdown when a laptop would boot up.



  • log in to the switch.... and then

    sho log -r
    

    That will show you the most recent entries in the log. Look for anything related to STP.



  • I will have a look at the switch when I get on site. What you're saying makes a lot of sense.



  • @dafyre said in Ethernet link going down and then up after 3 seconds.:

    log in to the switch.... and then

    sho log -r
    

    That will show you the most recent entries in the log. Look for anything related to STP.

    I think it is:

    log -r -w
    

    Without the 'show'. The -w switch helps filtering out less relevant stuff.


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