A Linux bridge behaves like a network switch. It forwards packets between interfaces that are connected to it. It’s usually used for forwarding packets on routers, on gateways, or between VMs and network namespaces on a host. It also supports STP, VLAN filter, and multicast snooping.

How does a bridge interface work?

The bridge interface is a function that accommodates multiple interfaces in one virtual interface and bridges those interfaces. Each accommodated interface connected to a physical segment is handled as one segment.

What does Linux bridge use to forward traffic?

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.