What is a bridge domain in Cisco ACI?

A bridge domain in Cisco ACI serves as a logical construct that functions as a forwarding domain specifically for all Layer 2 traffic. Each bridge domain can span one or more physical or virtual networks and allows for the segmentation of broadcast domains, effectively managing and containing broadcast traffic within a specified area. This setup facilitates the efficient handling of traffic, as it delineates how Layer 2 frames are processed, ensuring that they are forwarded appropriately based on the network policies and configurations set in ACI.

Choosing bridge domains correctly is crucial for maintaining network performance and segmentation, as it allows for flexibility in defining how various tenant networks interact. This is particularly important in a multi-tenant environment where isolation and security are key requirements. Therefore, defining a bridge domain optimally aligns with the hierarchical design and operational philosophies structured within Cisco ACI’s architecture.