According to Juniper’s Validated Designs (JVD) for campus fabrics, the Campus Fabric IP Clos (often referred to as a 5-stage Clos) is the architecture specifically engineered for high-scale environments supporting 10,000+ users. This design is characterized by extending the EVPN control plane and VXLAN data plane all the way to the access layer. By terminating VXLAN tunnels at the access switch—functioning as a Virtual Tunnel Endpoint (VTEP)—the network can seamlessly support both Layer 2 and Layer 3 devices directly at the edge of the fabric.

The primary driver for choosing IP Clos in large-scale deployments is its superior scalability. In this model, the core switches are shielded from the massive table sizes required to learn thousands of individual endpoint MAC and IP addresses. Instead, core devices only need to maintain reachability to the loopback addresses of the access layer switches. This reduction in the "flood and learn" pressure on the core is critical as the number of endpoints grows, ensuring that the core can scale far into the future with predictable growth.

Additionally, the IP Clos architecture provides the most flexible environment for microsegmentation using Group-Based Policies (GBP) and macrosegmentation using Virtual Routing and Forwarding (VRF) instances. Since routing occurs at the access device, "east-west" traffic between local endpoints remains efficient and does not need to traverse the distribution or core tiers. While EVPN Multihoming and Core-Distribution (CRB/ERB) models are effective for smaller sites or brownfield environments where access switches are legacy Layer 2-only devices, only the IP Clos architecture provides the end-to-end VXLAN capability required for high-density, future-proof campus fabrics.