NetworkManager报告"Error: Connection activation failed: No suitable device found for this connection." 且网络服务可能进入失败状态

环境

• Red Hat Enterprise Linux 7
• NetworkManager

问题

• 当尝试使用nmcli激活连接时，看到以下错误：

  [root@r75 ~]# nmcli con up ens9
  Error: Connection activation failed: No suitable device found for this connection.
  

• 在启动时或重新启动network.service时，systemd会记录一个错误，并将服务标记为failed：

  [root@r75 ~]# systemctl restart network.service
  Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
  
  [root@r75 ~]# systemctl -l status network.service
  ● network.service - LSB: Bring up/down networking
     Loaded: loaded (/etc/rc.d/init.d/network; bad; vendor preset: disabled)
     Active: failed (Result: exit-code) since Fri 2018-10-26 05:21:15 EDT; 31s ago
   Docs: man:systemd-sysv-generator(8)
    Process: 12078 ExecStop=/etc/rc.d/init.d/network stop (code=exited, status=0/SUCCESS)
    Process: 12261 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)
  
  Oct 26 05:21:14 r75.example.com systemd[1]: Starting LSB: Bring up/down networking...
  Oct 26 05:21:14 r75.example.com network[12261]: Bringing up loopback interface:  [  OK  ]
  Oct 26 05:21:14 r75.example.com network[12261]: Bringing up interface ens9:  Error: Connection activation failed: No suitable device found for this connection.
  Oct 26 05:21:14 r75.example.com network[12261]: [FAILED]
  Oct 26 05:21:14 r75.example.com network[12261]: Bringing up interface eth0:  Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/2)
  Oct 26 05:21:14 r75.example.com network[12261]: [  OK  ]
  Oct 26 05:21:15 r75.example.com systemd[1]: network.service: control process exited, code=exited status=1
  Oct 26 05:21:15 r75.example.com systemd[1]: Failed to start LSB: Bring up/down networking.
  Oct 26 05:21:15 r75.example.com systemd[1]: Unit network.service entered failed state.
  Oct 26 05:21:15 r75.example.com systemd[1]: network.service failed.
  

解决方案

Connection activation failed: No suitable device found for this connection. 错误可能有多个原因

• 确保与配置文件关联的接口将其链接报告为LOWER_UP。如果存在NO-CARRIER标志，NetworkManager将不会激活连接配置文件：

  [root@r75 ~]# ip link show ens9
  3: ens9: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT qlen 1000
      link/ether 52:54:00:0d:b7:5b brd ff:ff:ff:ff:ff:ff
  

  • 如果链路断开，很可能是物理连接问题（没有插入网线、网线损坏、交换机断开等）。

  • 或者，如果链接断开，系统不需要它，更改相关的连接配置文件，使其不会自动激活，从而避免错误：

    # nmcli con modify ens9 connection.autoconnect no
    

• 如果连接配置文件设置了MAC地址，请确保它与接口匹配。如果它们不匹配，请更正差异：

  [root@r75 ~]# nmcli con show ens9 | grep 802-3-ethernet.mac-address:
  802-3-ethernet.mac-address:             c7:1d:90:f7:8a:dd
  
  [root@r75 ~]# ip link show ens9
  3: ens9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
      link/ether 52:54:00:0d:b7:5b brd ff:ff:ff:ff:ff:ff
  
  [root@r75 ~]# nmcli con modify ens9 802-3-ethernet.mac-address 52:54:00:0d:b7:5b
  [root@r75 ~]# nmcli con up ens9
  Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/4)
  

根本原因

• Connection activation failed: No suitable device found for this connection. 错误最常见的是在尝试激活没有载体的接口（无论是手动还是自动）时出现。