ACI - Bridge Groups

In the Cisco Application Centric Infrastructure (ACI) architecture, the Bridge Group (BG) concept is equivalent to a traditional VLAN in a networking context. A Bridge Group is essentially a Layer 2 domain where you can group together a set of related endpoints.

Bridge Domain Interfaces (BDIs) and Bridged Virtual Interfaces (BVIs) are both concepts related to Bridge Groups.

  • A BDI is a logical interface that allows bidirectional flow of traffic between a routed interface and a bridge group within the same network. It’s a routed interface that represents a set of interfaces that are bridged.
  • A BVI, on the other hand, is used in bridging environments where you want to enable IP connectivity to the bridge group. The BVI provides a means to route traffic between different VLANs.

In terms of their relationship, a Bridge Group can contain one or more BDIs or BVIs. The BDI or BVI allows the Bridge Group to communicate with other Bridge Groups or with routed interfaces. In essence, the BDI or BVI provides the “gateway” for the Bridge Group’s Layer 2 traffic to be routed.