现在我这里主机有如下两块网卡：
$ ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.0.1.201 netmask 255.255.255.0 broadcast 10.0.1.255
inet6 fe80::460b:4f00:49d1:2865 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:c4:03:2f txqueuelen 1000 (Ethernet)
RX packets 62 bytes 8044 (7.8 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 58 bytes 9130 (8.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.16.1.201 netmask 255.255.255.0 broadcast 172.16.1.255
inet6 fe80::5091:4f3a:ff97:359d prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:c4:03:39 txqueuelen 1000 (Ethernet)
RX packets 2 bytes 141 (141.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 21 bytes 1632 (1.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
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 1000 (Local Loopback)
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
桥接设备的管理依赖于 brctl 工具，先安装软件包：
$ yum install bridge-utils -y
以使用 eth0 创建桥接网卡为例，有如下几种方式。
注意：务必关闭 NetworkManager 服务。
方式一：手动配置
1、创建桥接网卡配置文件：
$ cd /etc/sysconfig/network-scripts
$ cp ifcfg-eth0 ifcfg-br0
2、编辑桥接网卡配置文件：
$ vim ifcfg-br0
# 虚拟桥设备充当主机网卡
NAME=br0
DEVICE=br0
BOOTPROTO=none
NM_CONTROLLED=no
ONBOOT=yes
TYPE=Bridge
IPADDR=10.0.1.201
PREFIX=24
GATEWAY=10.0.1.2
DNS1=10.0.1.2
3、修改 eth0 配置文件：
$ vim ifcfg-eth0
# 原物理网卡充当交换机，不需要 IP、网关及 DNS。
NAME=eth0
DEVICE=eth0
BOOTPROTO=none
NM_CONTROLLED=no
ONBOOT=yes
TYPE=Ethernet
# 明确指定桥到 br0
BRIDGE=br0
4、重启网卡，查看网卡信息如下：
$ systemctl restart network
$ ifconfig
br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.0.1.201 netmask 255.255.255.0 broadcast 10.0.1.255
inet6 fe80::20c:29ff:fec4:32f prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:c4:03:2f txqueuelen 1000 (Ethernet)
RX packets 2 bytes 98 (98.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 16 bytes 1624 (1.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether 00:0c:29:c4:03:2f txqueuelen 1000 (Ethernet)
RX packets 1103 bytes 125183 (122.2 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 663 bytes 147661 (144.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.16.1.201 netmask 255.255.255.0 broadcast 172.16.1.255
inet6 fe80::20c:29ff:fec4:339 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:c4:03:39 txqueuelen 1000 (Ethernet)
RX packets 2228 bytes 245167 (239.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1333 bytes 515291 (503.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
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 1000 (Local Loopback)
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
可通过 brctl 查看桥设备：
$ brctl show
bridge name bridge id STP enabled interfaces
br0 8000.000c29c4032f no eth0
方式二：命令行配置
1、添加桥接设备：
$ brctl addbr br0
# 可通过 ip a 或 ifconfig -a 查看到新添加的桥设备
2、拆掉 eth0 的地址：
$ ifconfig eth0 0 up
3、把桥设备关联到 eth0：
$ brctl addif br0 eth0
4、给桥设备添加地址并启用：
$ ifconfig br0 10.0.1.201/24 up
5、查看网卡信息如下：
$ ifconfig
br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.0.1.201 netmask 255.255.255.0 broadcast 10.0.1.255
inet6 fe80::20c:29ff:fec4:32f prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:c4:03:2f txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 6 bytes 516 (516.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::ae3d:c19c:1bdf:10df prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:c4:03:2f txqueuelen 1000 (Ethernet)
RX packets 5943 bytes 8638758 (8.2 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1698 bytes 104117 (101.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.16.1.201 netmask 255.255.255.0 broadcast 172.16.1.255
inet6 fe80::5091:4f3a:ff97:359d prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:c4:03:39 txqueuelen 1000 (Ethernet)
RX packets 405 bytes 45762 (44.6 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 283 bytes 68554 (66.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
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 1000 (Local Loopback)
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
建议启动 stp：
brctl stp br0 on。