1. About Network Bridge
A network bridge is a Link Layer device which forwards traffic between networks based on MAC addresses and is therefore also referred to as a Layer 2 device.
It makes forwarding decisions based on tables of MAC addresses which it builds by learning what hosts are connected to each network.
A software bridge can be used within a Linux host in order to emulate a hardware
bridge, for example in virtualization applications for sharing a NIC with one or more virtual NICs.
Example： Sample ifcfg-br0 interface configuration file
Example：Sample ifcfg-eth0 interface configuration file