A bridge interface is actually a virtual interface handled by a config file on your Linux system. Creating a bridge is quite simple, just follow those steps and you’re all set!
1. Create the bridge interface configuration file :
vi /etc/sysconfig/network-scripts/ifcfg-br0
Add the the following parameters :
DEVICE=br0 TYPE=Bridge BOOTPROTO=static ONBOOT=yes STP=on IPADDR= NETMASK= GATEWAY= DNS1=
2. Configure the physical interface member of the bridge with those values :
DEVICE=eth0 BOOTPROTO=static HWADDR= ONBOOT=yes NETMASK= GATEWAY= BRIDGE=br0 TYPE=Ethernet
As you can see, there is no IP address on the physical interface because they belong to the bridge. For the gateway and netmask, simply add the same as you are using on the bridge interface.