这个问题困扰了我好几天。我在 PowerKVM 主机上运行 Ubuntu 14.04 客户机（PowerKVM 是 IBM Power Systems 上的 KVM，所以基本上就是 KVM。）。我无法让桥接网络工作。我甚至无法 ping 默认网关。我猜是 XML 配置文件出了问题。
这些是文件。
KVM 主机
localhost:/root # ifconfig -a
brenP3p5s0f3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.16.229.200 netmask 255.255.255.192 broadcast 172.16.229.255
inet6 fe80::42f2:e9ff:fe5d:61bb prefixlen 64 scopeid 0x20<link>
ether 40:f2:e9:5d:61:bb txqueuelen 0 (Ethernet)
RX packets 40709 bytes 3013319 (2.8 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 38 bytes 6015 (5.8 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
enP3p5s0f0: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 40:f2:e9:5d:61:b8 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 252
enP3p5s0f1: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 40:f2:e9:5d:61:b9 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 253
enP3p5s0f2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.16.229.199 netmask 255.255.255.192 broadcast 172.16.229.255
inet6 fe80::42f2:e9ff:fe5d:61ba prefixlen 64 scopeid 0x20<link>
ether 40:f2:e9:5d:61:ba txqueuelen 1000 (Ethernet)
RX packets 36345 bytes 4200608 (4.0 MiB)
RX errors 0 dropped 2 overruns 0 frame 0
TX packets 23689 bytes 12817261 (12.2 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 252
enP3p5s0f3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::42f2:e9ff:fe5d:61bb prefixlen 64 scopeid 0x20<link>
ether 40:f2:e9:5d:61:bb txqueuelen 1000 (Ethernet)
RX packets 32473 bytes 2927091 (2.7 MiB)
RX errors 0 dropped 3080 overruns 0 frame 0
TX packets 364 bytes 78478 (76.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 253
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 108802 bytes 28022560 (26.7 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 108802 bytes 28022560 (26.7 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:7b:a3:23 txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr1: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.121.1 netmask 255.255.255.0 broadcast 192.168.121.255
ether 52:54:00:1e:11:18 txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0-nic: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 52:54:00:7b:a3:23 txqueuelen 500 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr1-nic: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 52:54:00:1e:11:18 txqueuelen 500 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
主机的路由表
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 172.16.229.193 0.0.0.0 UG 0 0 0 enP3p5s0f2
169.254.0.0 0.0.0.0 255.255.0.0 U 1004 0 0 enP3p5s0f2
169.254.0.0 0.0.0.0 255.255.0.0 U 1039 0 0 brenP3p5s0f3
172.16.229.192 0.0.0.0 255.255.255.192 U 0 0 0 enP3p5s0f2
172.16.229.192 0.0.0.0 255.255.255.192 U 0 0 0 brenP3p5s0f3
192.168.121.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr1
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
保存在主机中的客户机 XML 文件（界面部分）。
localhost:/root # virsh edit ubuntu01
<interface type='bridge'>
<mac address='52:54:00:b8:bd:eb'/>
<source bridge='brenP3p5s0f3'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
主机中保存的桥接网络 XML 文件：
localhost:/root # cat /etc/libvirt/qemu/networks/bridged.xml
<network>
<name>bridged</name>
<uuid>01ebaa45-0034-4a3f-8d57-fe67e03130b6</uuid>
<forward mode='bridge'/>
<bridge name='brenP3p5s0f3'/>
</network>
客人
我无法复制/粘贴，因为我无法使用 ssh（因为它无法访问），而且 virsh 上的控制台不知何故不起作用。但是，当我启动虚拟机时，我看不到定义的 ip 地址。然后我做了以下事情：
ifconfig eth0 172.16.229.201 netmask 255.255.255.192 up
ip route add default via 172.16.229.193
主机的默认网关也相同。我使用的网络掩码对于客户机和主机都相同。
问题：当我 ping 默认网关时，出现错误“目标主机无法访问”。当我 ping 自己 172.16.229.201 时，可以成功 ping。
一个更新：尝试 tcpdump 默认网关的 IP 地址时发生了一个有趣的行为：我得到了类似这样的信息：
ARP, Request who-has 10.10.10.6 tell 10.10.10.105, length 46
ARP, Request who-has 10.10.10.6 tell 10.10.10.102, length 46
ARP, Request who-has 10.10.10.252 tell 10.10.10.253, length 46
IP 10.10.10.2.1985 > 224.0.0.102.1985: HSRPv1
像这样的多行。我不知道它从哪里获取这些 IP 地址。“有趣”的是，我通过 tcpdump 主机上的桥接接口获得了相同的输出！因此，看起来 tcpdump 正在以某种方式从客户机访问网络！否则我无法解释为什么这些行是相同的。我想强调的是，这些以 10 开头的私有 IP 地址未在我的子网中的任何地方分配。
任何想法？
提前致谢！