When using RFC 3069 and bonding, backup slave is always down in RHEL 4 and 5

Solution Verified - Updated -


  • When we failover the eth0 (primary slave), it does failover to eth1; however, the "MII Status" of eth1 interface under /proc/net/bonding/bond0 shows as "down".  After approximately 11s, eth3 becomes primary and eth2's "MII Status" is marked as being "down".
  • While failing back to primary eth2, it simply does not happen. eth3 remains as active slave, even though I have 'primary=eth2' flag set in my /etc/modprobe.conf


  • Red Hat Enterprise Linux (RHEL) 4 and 5

  • Bonded interface using mode=1, with a primary interface specified and ARP monitoring

  • Network environment using RFC 3069, also known as VLAN aggregation, private VLAN, source-port filtering, and port isolation

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