Overview
A transparent bridge is a data-link layer (layer 2) relay device that connects two or more networks or network systems. When a transparent bridge powers up, it automatically begins learning the network topology by examining the media access control (MAC) source address of every incoming packet. The bridge then creates an entry in the forwarding table consisting of the address and associated interface where the packet was received.
You configure transparent bridging by creating one or more bridge groups on the system (you must do this using the CLI). A bridge group is a collection of network interfaces (ports) that forms a broadcast domain. Each bridge group has its own set of forwarding tables and filters and, as such, functions as a logical transparent bridging device.
After you create a bridge group, you assign one or more network interfaces with the bridge group. The association is called a bridge group interface, or simply bridge interface.
You can configure bridge interfaces to add transparent bridging capabilities to your existing network configurations. Currently, bridge interfaces can be stacked on: