Which type of connection is supported by Layer 3 in the Cisco ACI fabric?

In Cisco ACI, eBGP can be configured over an OSPF adjacency, meaning OSPF establishes the routing path between the ACI fabric border leaf nodes and external routers, and then eBGP sessions exchange routes over this established OSPF connectivity.

While ACI supports both eBGP and EIGRP for external connections, 'eBGP over EIGRP' is not a standard or supported combination where EIGRP would directly provide the transport for eBGP sessions in this manner.

ACI does not natively support RIP for L3 external connectivity, and 'eBGP over RIP' is not a recognized or supported routing configuration in ACI.

iBGP is typically used within an autonomous system, and 'iBGP over EIGRP' is not a standard or supported method for external Layer 3 connections in Cisco ACI; ACI uses internal MP-BGP for fabric routing.