The scenario requires a high-performance network for AI workloads without any Layer 2 VLAN requirements. An IP fabric using External BGP (EBGP) is a pure Layer 3 architecture that perfectly fits this need. In this design, each link between devices (e.g., leaf-to-spine) is a routed point-to-point link, and BGP is used to exchange reachability information for server endpoints. This approach is highly scalable, stable, and avoids the complexities of Layer 2 protocols and overlay technologies like VXLAN, which are unnecessary when L2 adjacency is not required.

A. an IP fabric using PIM-SM to signal VXLAN overlay: VXLAN is an overlay technology designed to extend Layer 2 segments, which is explicitly not a requirement.

B. an IP fabric using the EVPN-MPLS architecture: EVPN-MPLS is primarily used for extending Layer 2 and Layer 3 VPN services, which adds unnecessary complexity when only L3 connectivity is needed.

C. an IP fabric with an EVPN-VXLAN architecture: This is a common data center architecture, but its main purpose is to provide Layer 2 overlay services, which contradicts the stated requirement.

1. Juniper Networks TechLibrary. (2023). IP Fabric Underlay Network Design and Implementation. "An IP fabric is a simple, scalable, and resilient architecture that is built on a Layer 3-only infrastructure... In an IP fabric, we recommend using EBGP as the routing protocol between the leaf and spine devices."

2. Juniper Networks Day One+. (2022). Data Center Fundamentals. Chapter 3: "Data Center Architectures", Section: "IP Fabric". This section describes the IP Fabric as a two-tier spine-and-leaf architecture using BGP for routing, ideal for modern data centers that do not require L2 extension.