在 RHEL 7.4 上启用带有非零 "updelay" 的绑定出现问题，系统在日志中不断记录 "bond: link status up for interface, enabling it in ms" 信息，绑定 slave MII 的状态为 DOWN

Issue

• 使用非零 updelay 配置启动绑定网络无法正确组成绑定接口，或在主接口没有响应时不会出现故障转移。

• RHEL 7.4 系统在日志中不断记录 "bond: link status up for interface, enabling it in ms" 信息，绑定 slave MII 的状态为 DOWN

• 系统不断记录相同的 "link status up" 信息：

  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
  

• 另外，对于这些接口，MII Status 始终显示为 down ：

  $ 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
  

• 这个程序错误可能不会 100% 被触发，但可能会在通过 sysfs 为绑定删除接口并重新添加接口时出现。