Even though bonding has been configured for mode 1 [active backup], it still shows as Mode 0 [Round-Robin]

Solution Verified - Updated

Environment

  • Red Hat Enterprise Linux, all versions

Issue

  • Although the system has been configured with mode 1 bonding in /etc/modprobe.conf, running cat /proc/net/bonding/bond0 still shows the bonding to be configured as mode 0 [round-robin]:

        Ethernet Channel Bonding Driver: v2.6.3-rh (June 8, 2005)

    Bonding Mode: load balancing (round-robin)
    MII Status: up
    MII Polling Interval (ms): 100
    Up Delay (ms): 0
    Down Delay (ms): 0

    Slave Interface: eth0
    MII Status: up
    Link Failure Count: 0
    Permanent HW addr: 00:0c:29:40:be:67

    Slave Interface: eth1
    MII Status: up
    Link Failure Count: 0
    Permanent HW addr: 00:0c:29:40:be:71

Resolution

  • Reload the bonding driver or reboot the system. To reload the bonding driver:

       # service network stop
   # modprobe -r -v bonding     -- or # modprobe -r -v bonding -o bond0
   # service network start

  • Running cat /proc/net/bonding/bond0 now shows mode 1:

       Ethernet Channel Bonding Driver: v2.6.3-rh (June 8, 2005)

   Bonding Mode: fault-tolerance (active-backup)
   Primary Slave: None
   Currently Active Slave: eth0
   MII Status: up
   MII Polling Interval (ms): 100
   Up Delay (ms): 0
   Down Delay (ms): 0

   Slave Interface: eth0
   MII Status: up
   Link Failure Count: 0
   Permanent HW addr: 00:0c:29:40:be:67

   Slave Interface: eth1
   MII Status: up
   Link Failure Count: 0
   Permanent HW addr: 00:0c:29:40:be:71

  • Another possible resolution that can be applied is to update the version of initscripts and its dependencies.
    Previous version such as initscripts-9.03.31-2.el6.x86_64 on Rhel 6.3 has been known to cause this issue.

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