HPE Aruba DC Fabric: EVPN-VXLAN with Fabric Composer

Building a data center fabric by hand is error-prone: underlay addressing, overlay VNI planning, VSX pairs, and BGP route reflectors all have to line up perfectly. HPE Aruba Networking's Fabric Composer automates most of that work through a guided setup process that provisions the routed underlay, the EVPN-VXLAN overlay, and VMware vCenter integration in one flow. Based on the official HPE Aruba Validated Solution Guide, this article explains the key design decisions — naming conventions, address blocks, VTEP loopbacks, and VNI numbering — plus the end-to-end configuration sequence you need to understand even when the wizard does the typing.

Physical Topology and Fabric Roles

The validated design uses spine and leaf switches: leaves act as the VXLAN Tunnel Endpoints (VTEPs), spines provide underlay transit and run BGP route reflectors for the overlay. Server access switches connect as VSF stacks below the leaf pair. A clear naming convention that encodes type, role, and location — for example RSVDC-FB1-SP1 (Spine 1) and RSVDC-FB1-LF1-1 (Leaf pair 1, member 1) — simplifies operation at production scale.

Underlay and Overlay Addressing

Fabric Composer allocates addresses automatically from network ranges you provide:

• Leaf-spine links: a /24 block from which /31 point-to-point L3 links are carved (example 10.255.0.0/23).
• Loopback / VSX transit / keepalive: unique /32 loopbacks per switch plus /31 transit and keep-alive links (example 10.250.0.0/23).
• VTEP addresses: a single /32 loopback common to both ToR peers in a VSX pair, defining one logical VTEP per rack (example 10.250.2.0/24).

VNI Numbering Scheme

Plan VNI values before the wizard runs so they never overlap:

• L2 VNI = VLAN ID + 10000 (VLAN 100 → L2 VNI 10100).
• L3 VNI = overlay number + 100000 (Overlay 1 → L3 VNI 100001).

Each L3 VNI maps to a VRF; each L2 VNI maps to a VLAN ID. iBGP carries the EVPN address family between leaves, with two spines acting as route reflectors and all leaves as clients.

MAC Address Best Practices

Use a Locally Administered Address (LAA) — x2/x6/xA/xE-xx-xx-xx-xx-xx — for the switch virtual MAC, VSX system MAC, or Active Gateway MAC. Reuse the same Active Gateway MAC for every Active Gateway IP assignment, since only a small number of unique virtual MACs can be configured per switch.

Guided Setup Sequence

Fabric Composer's guided setup follows this order: switch discovery → fabric creation → switch assignment → switch profiles and split ports → NTP/DNS → VSX configuration on ToR leaf pairs → leaf/spine IP assignment → OSPF underlay → iBGP overlay → EVPN mapping of VLANs to VNIs. After the wizard, you still configure host onboarding, MC-LAG for hosts, border leaf routing, PIM-SM/IGMP for overlay multicast, and testing loopbacks.

If you are comparing implementations, see our VXLAN with MP-BGP EVPN design and configuration guide, the 400G spine / 100G leaf link consistency article, and for the multi-chassis side of leaf pairs the Arista EOS MLAG explainer.

原文链接：https://arubanetworking.hpe.com/techdocs/VSG/docs/050-dc-deploy/esp-dc-deploy-120-fabric-deploy/