Which statement is correct about a collapsed fabric EVPN-VXLAN architecture?

In an EVPN-VXLAN fabric, connectivity to external networks is provided by a border gateway function. This function can reside on the spine devices (in a centrally-routed bridging model) or on dedicated leaf devices, known as border leaf devices (in an edge-routed bridging model). A collapsed fabric architecture is a common spine-leaf design where placing the border gateway function on specific border leaf devices is a valid and frequently used implementation pattern for external connectivity.

A. Inter-spine links are not used in a standard Clos-based spine-leaf fabric topology, which aims for non-blocking, predictable performance between leaf devices.

C. Using Virtual Chassis (VC) at the leaf layer is generally not recommended for high resiliency as it creates a single control plane, making it a single point of failure. ESI-LAG is preferred.

B. EVPN-VXLAN is a standards-based technology that supports multi-vendor interoperability; there is no requirement that all spine devices must be from a single vendor.

1. Juniper Networks. (2021). Data Center Fabric Design and Implementation Guide. "Border Gateway Routing," p. 21. This guide discusses the role of border leaf devices for connecting the data center to the outside world.

2. Juniper Networks. (2023). EVPN-VXLAN Campus Architectures. "Core-Distribution Layer," p. 10. Describes collapsed core designs where border gateway functions are integrated.

3. Juniper Networks. (2023). EVPN Multihoming Overview. This document explains that ESI-LAG provides higher resiliency than MC-LAG or Virtual Chassis in data center fabrics.