Issue

Bonding interface used to set up a xen bridge works normally when configured in mode 1(or active-backup) but when an interface fails and comes up, it is not active.

In this example, eth13 cannot be joined to the bonding interface once it comes up after failing:

      Bonding Mode: fault-tolerance (active-backup)
      Primary Slave: None
      Currently Active Slave: eth14
      MII Status: up
      MII Polling Interval (ms): 100
      Up Delay (ms): 0
      Down Delay (ms): 0

      Slave Interface: eth10
      MII Status: up
      Link Failure Count: 1
      Permanent HW addr: 00:24:81:7d:b3:ef

      Slave Interface: eth13
      MII Status: up
      Link Failure Count: 1
      Permanent HW addr: 00:24:81:7d:b9:ac

      Slave Interface: eth14
      MII Status: up
      Link Failure Count: 0
      Permanent HW addr: 00:24:81:7d:b9:af

      Slave Interface: eth2
      MII Status: up
      Link Failure Count: 1
      Permanent HW addr: 00:24:81:7d:8b:2f

      Slave Interface: eth6
      MII Status: up
      Link Failure Count: 0
      Permanent HW addr: 00:24:81:7d:bb:43

      Slave Interface: eth9
      MII Status: up
      Link Failure Count: 0
      Permanent HW addr: 00:24:81:7d:b3:ec

      ifdown eth13
      /etc/sysconfig/network-scripts/ifdown-eth: line 101: /sys/class/net/bond2/bonding/slaves: No such file or directory
      Jul 30 10:10:03 dl785-1 kernel: bonding: pbond2: link status definitely down for interface eth13, disabling it
      Jul 30 10:10:03 dl785-1 kernel: bonding: pbond2: making interface eth14 the new active one.
      Jul 30 10:10:03 dl785-1 kernel: device eth13 left promiscuous mode
      Jul 30 10:10:03 dl785-1 kernel: device eth14 entered promiscuous mode

      ifup eth13
      grep: /sys/class/net/bond2/bonding/slaves: No such file or directory
      /etc/sysconfig/network-scripts/ifup-eth: line 110: /sys/class/net/bond2/bonding/slaves: No such file or directory

      [root@dl785-1 ~]# brctl show
      bridge name     bridge id               STP enabled     interfaces
      virbr0          8000.000000000000       yes
      xenbr0          8000.000000000000       no
      xenbr1          8000.feffffffffff       no              pman0
                                                              vif0.1
      xenbr2          8000.0024817db3ef       no              pbond2