引导时网桥无法通过DHCP获取IP

我正在运行CentOS7。我没有在运行NetworkManager，实际上已经将其卸载。

我的系统应该br0在启动时通过DHCP获取IPv4地址。但是，当我登录时，没有地址。

我的配置：

# pwd
/etc/sysconfig/network-scripts

# cat ifcfg-enp5s0 
DEVICE=enp5s0
ONBOOT="yes"
BRIDGE=br0

# cat ifcfg-br0 
DEVICE=br0
ONBOOT=yes
TYPE=Bridge
BOOTPROTO=dhcp
STP=on
DELAY=0

请注意，我没有手动配置此网桥。virt-manager当我br0在此对话框中添加内容时：

相关journalctl --boot | grep '\(\<br0\>\|enp5s0\)'和上下文：

Jan 08 21:04:32 jonathon-centos7 kernel: r8169 0000:05:00.0 enp5s0: link down
Jan 08 21:04:32 jonathon-centos7 kernel: IPv6: ADDRCONF(NETDEV_UP): enp5s0: link is not ready
Jan 08 21:04:32 jonathon-centos7 kernel: r8169 0000:05:00.0 enp5s0: link down
Jan 08 21:04:32 jonathon-centos7 kernel: device enp5s0 entered promiscuous mode
Jan 08 21:04:32 jonathon-centos7 network[947]: Bringing up interface enp5s0:  [  OK  ]
...
Jan 08 21:04:32 jonathon-centos7 network[947]: Bringing up interface br0:
Jan 08 21:04:32 jonathon-centos7 kernel: IPv6: ADDRCONF(NETDEV_UP): br0: link is not ready
...
Jan 08 21:04:34 jonathon-centos7 kernel: r8169 0000:05:00.0 enp5s0: link up
Jan 08 21:04:34 jonathon-centos7 kernel: IPv6: ADDRCONF(NETDEV_CHANGE): enp5s0: link becomes ready
Jan 08 21:04:34 jonathon-centos7 kernel: br0: port 1(enp5s0) entered listening state
Jan 08 21:04:34 jonathon-centos7 kernel: br0: port 1(enp5s0) entered listening state
//// (Note: 2 second delay here, with no other events)
Jan 08 21:04:36 jonathon-centos7 avahi-daemon[957]: Registering new address record for fe80::f66d:4ff:fe3b:c24e on enp5s0.*.
Jan 08 21:04:36 jonathon-centos7 kernel: br0: port 1(enp5s0) entered learning state
///// (Too soon!)
Jan 08 21:04:38 jonathon-centos7 network[947]: Determining IP information for br0... failed; no link present.  Check cable?
Jan 08 21:04:38 jonathon-centos7 network[947]: [FAILED]
Jan 08 21:04:38 jonathon-centos7 systemd[1]: network.service: control process exited, code=exited status=1
Jan 08 21:04:38 jonathon-centos7 systemd[1]: Failed to start LSB: Bring up/down networking.
Jan 08 21:04:38 jonathon-centos7 systemd[1]: Unit network.service entered failed state.
...
Jan 08 21:04:38 jonathon-centos7 kernel: br0: topology change detected, propagating
Jan 08 21:04:38 jonathon-centos7 kernel: br0: port 1(enp5s0) entered forwarding state
Jan 08 21:04:38 jonathon-centos7 kernel: IPv6: ADDRCONF(NETDEV_CHANGE): br0: link becomes ready
Jan 08 21:04:39 jonathon-centos7 avahi-daemon[957]: Registering new address record for fe80::f66d:4ff:fe3b:c24e on br0.*.
Jan 08 21:04:41 jonathon-centos7 avahi-daemon[957]: Registering new address record for 2605:a000:1315:8119:f66d:4ff:fe3b:c24e on br0.*.
Jan 08 21:04:41 jonathon-centos7 avahi-daemon[957]: Withdrawing address record for fe80::f66d:4ff:fe3b:c24e on br0.

///// (Here's where I entered `ifup br0`)
Jan 08 22:43:30 jonathon-centos7 dhclient[5009]: DHCPDISCOVER on br0 to 255.255.255.255 port 67 interval 6 (xid=0x25f649b7)
Jan 08 22:43:31 jonathon-centos7 dhclient[5009]: DHCPREQUEST on br0 to 255.255.255.255 port 67 (xid=0x25f649b7)
Jan 08 22:43:34 jonathon-centos7 avahi-daemon[957]: Joining mDNS multicast group on interface br0.IPv4 with address 10.0.1.128.
Jan 08 22:43:34 jonathon-centos7 avahi-daemon[957]: New relevant interface br0.IPv4 for mDNS.
Jan 08 22:43:34 jonathon-centos7 avahi-daemon[957]: Registering new address record for 10.0.1.128 on br0.IPv4.
Jan 08 23:43:17 jonathon-centos7 dhclient[5124]: DHCPREQUEST on br0 to 10.0.1.1 port 67 (xid=0x25f649b7)

系统启动并登录后，我可以打开一个终端，并：

# ifup br0
set forward delay failed: Numerical result out of range

Determining IP information for br0... done.

然后，我连接到我的网络。

为什么我br0在启动时无法获得IP ？

有关：

• 带有dhcp的以太网桥 [CentOS形式]

笔记：

• brctl showstp br0显示前向延迟设置为2.00。brctl setfd br0 0显示与相同的错误ifup br0。看来virt-manager指定了的无效DELAY=0值br0。
• 在日志中找到重要条目后，似乎systemd正在尝试获取IP，br0然后再进入转发状态。
• 我已经在CentOS错误跟踪器上打开了错误8086。

您的网桥不受网络初始化脚本的控制，而由libvirt控制。libvirtd服务启动时，网桥应该启动。

我不会这样跑。我将使网桥由网络初始化脚本控制，而在libvirt配置中没有网桥。

您现在拥有的ifcfg-文件就可以了。只需从libvirt中删除配置，确保您仍然有那些文件，然后chkconfig network on

是的，chkconfig可在EL7上使用。

来自http://www.microhowto.info/howto/persistently_bridge_traffic_between_two_or_more_ethernet_interfaces_on_redhat.html的引用：

因此，在某些简单情况下（例如，将一组虚拟机桥接到单个物理接口时），您可能希望禁用STP。

禁用STP似乎是使其正常工作的方法。

当网桥启动时，您的物理链接没有建立。给您的物理接口增加延迟。