Issues enabling bond with non-zero `updelay` on RHEL 7.4 and system repeatedly logs "bond: link status up for interface, enabling it in ms" and bonding slave MII status is DOWN

Solution Verified - Updated -

Issue

  • Starting a bonded network with a non-zero updelay configuration neither forms the bond interface properly, nor fails over if their primary interface becomes unresponsive.

  • RHEL 7.4 system repeatedly logs "bond: link status up for interface, enabling it in ms" and bonding slave MII status is DOWN

  • System repeatedly logs the same "link status up" message:

    Aug 17 14:21:00 localhost kernel: bond0: link status up for interface eth6, enabling it in 2000 ms
    Aug 17 14:21:00 localhost kernel: bond1: link status up for interface eth2, enabling it in 2000 ms
    Aug 17 14:21:00 localhost kernel: bond2: link status up for interface eth3, enabling it in 2000 ms
    Aug 17 14:21:00 localhost kernel: bond0: link status up for interface eth6, enabling it in 2000 ms
    Aug 17 14:21:00 localhost kernel: bond1: link status up for interface eth2, enabling it in 2000 ms
    Aug 17 14:21:00 localhost kernel: bond2: link status up for interface eth3, enabling it in 2000 ms
    Aug 17 14:21:00 localhost kernel: bond0: link status up for interface eth6, enabling it in 2000 ms
    Aug 17 14:21:01 localhost kernel: bond1: link status up for interface eth2, enabling it in 2000 ms
    Aug 17 14:21:01 localhost kernel: bond2: link status up for interface eth3, enabling it in 2000 ms
    Aug 17 14:21:01 localhost kernel: bond0: link status up for interface eth6, enabling it in 2000 ms
    Aug 17 14:21:01 localhost kernel: bond1: link status up for interface eth2, enabling it in 2000 ms
    Aug 17 14:21:01 localhost kernel: bond2: link status up for interface eth3, enabling it in 2000 ms
    Aug 17 14:21:01 localhost kernel: bond0: link status up for interface eth6, enabling it in 2000 ms
    
  • Additionally, the MII Status is always shown as down for these interfaces:

    $ cat /proc/net/bonding/bond0
    Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
    
    Bonding Mode: fault-tolerance (active-backup)
    Primary Slave: eth4 (primary_reselect always)
    Currently Active Slave: eth4
    MII Status: up
    MII Polling Interval (ms): 100
    Up Delay (ms): 2000
    Down Delay (ms): 0
    
    Slave Interface: eth4
    MII Status: up
    Speed: 10000 Mbps
    Duplex: full
    Link Failure Count: 0
    Permanent HW addr: 10:15:a4:d8:c2:1c
    Slave queue ID: 0
    
    Slave Interface: eth6
    MII Status: down
    Speed: 10000 Mbps
    Duplex: full
    Link Failure Count: 0
    Permanent HW addr: 10:15:a4:d8:c1:e0
    Slave queue ID: 0
    
  • The bug doesn't trigger 100% reliably, but can be provoked by removing and re-adding interfaces to the bond via sysfs.

Environment

  • Red Hat Enterprise Linux 7.4
  • Bonding

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