What is MP-BGP used for in Cisco ACl fabric?

In Cisco ACI fabric, MP-BGP (Multi-Protocol Border Gateway Protocol) is utilized for several purposes, one of which includes the propagation of L3Out (Layer 3 Out) routes within the fabric. Specifically, MP-BGP with VPNv4 address family (AF) is used in the ACI infra VRF (overlay-1 VRF) to distribute external routes from a border leaf to other leaf switches1. This allows for the efficient dissemination of routing information and ensures that all relevant leaf switches are aware of the routes necessary to reach external networks.

References :=

ACI Fabric L3Out White Paper - Cisco1

Configuring ACI Fabric BGP Route Reflectors - Cisco2

ACI Fabric - Underlying protocols - Cisco Community3

Cisco Application Centric Infrastructure Fundamentals, Release 5.3(x)4