EVPN fabric overview
An EVPN-VXLAN fabric uses EVPN as the control plane and VXLAN as the data plane to stretch Layer-2/Layer-3 segments across a spine-leaf underlay. It fits multi-tenant data centers and large campus cores that need scalable segmentation — not every branch office.
Key facts
- Control plane: EVPN (BGP address families)
- Data plane: VXLAN overlays on an IP underlay
- Primary pattern: spine-leaf with leaf VTEPs
Summary
Reference note for fabric roles and decision boundaries.
Audience
Data-center and campus fabric designers.
Prerequisites
- IP underlay with ECMP between leaves and spines
- Hardware/software that implements the required EVPN features
- Clear tenant/VRF segmentation model
Requirements
- Stable underlay MTU accounting for VXLAN overhead
- BGP design (route reflectors or equivalent)
- Operational tooling for overlay state visibility
Architecture / components
- Leaf: VTEP for servers/access; host overlays
- Spine: high-bandwidth underlay forwarding (often L3 only)
- Border/edge: interconnect to WAN, Internet, or legacy DC
- Route reflector / BGP design for EVPN address families
Workflow
- Validate underlay reachability and ECMP
- Enable EVPN address families and VTEP loopbacks
- Map VNI/VRF policy
- Verify control-plane routes before hosting production workloads
Configuration
Vendor-specific CLI is intentionally omitted. Follow platform documentation after the logical design is approved.
Verification
- EVPN route presence for expected VNIs/MACs/IPs
- East-west connectivity tests within and across VNIs per policy
- Leaf failure / ECMP rebalance checks
Troubleshooting
If overlays fail, prove underlay first (loopback ping, BGP session state, MTU), then inspect EVPN routes.
When not to use this pattern
Small single-switch sites, purely Layer-3 routed campuses without overlay requirements, or environments without EVPN-capable hardware should use simpler designs first.
Rollback
Keep underlay-only reachability for critical services during migration; retain pre-overlay configs for rapid restore.
References
Related guides
- EVPN-VXLAN technology — EVPN control plane with VXLAN data plane for scalable fabrics.
- Spine-leaf underlay pattern — Equal-cost multipath leaf-spine underlay used beneath overlays such as EVPN-VXLAN.
- Campus network reference architecture — Layered campus design: access, distribution/core, services edge.
Owner: Novatelia Engineering / AEO Program. Reviewed: 2026-07-22. Doc version: 2026.07. Change log: Phase 6 technical authority pilot.
No datasheet copies, fabricated benchmarks, or unverified vendor authorizations appear in this document.