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5️⃣ Lab 05 · VXLAN-EVPN DCI & Multi-Site (Border Gateway VTEPs)

✅ Validated on Arista cEOS 4.32.0F. All outputs captured live from fabric in OrbStack.

Time: ~50 minutes · Nodes: 8 (4 Spines/BGWs, 4 Leafs across 2 Datacenter Sites)

🧠 Technology Deep Dive: EVPN Multi-Site DCI Architecture

Connecting multiple geographically dispersed data centers (Data Center Interconnect / DCI) requires scaling EVPN beyond a single IP underlay domain:

+---------------------------------------------------------------------------------------------------+
| EVPN MULTI-SITE DCI ARCHITECTURE                                                                  |
+---------------------------------------------------------------------------------------------------+
| 1. Border Gateway (BGW) VTEPs: Act as control-plane and data-plane anchors between sites.         |
| 2. Overlay Index & Path Decoupling: Hides internal leaf VTEPs behind the Border Gateway.           |
| 3. Distributed Anycast Gateway Across Sites: Enables live VM migration between DC1 and DC2.      |
+---------------------------------------------------------------------------------------------------+

1. Border Gateway (BGW) VTEP Mechanics

  • Internal Fabric: Leaf VTEPs run BGP EVPN peering to local Spines/BGWs.
  • Inter-Site WAN: Border Gateways (bgw1 in DC1 ↔ bgw2 in DC2) peer over eBGP EVPN (AFI 25 / SAFI 70).
  • NLRI Re-Origination: Border Gateways rewrite the BGP Next-Hop on all EVPN Route Types (2, 3, 5) to their local Border VTEP IP, preventing internal VTEP IPs from leaking into the WAN.

Step 1 · Border Gateway (BGW) Configuration

Configure Multi-Site Border Gateway on bgw1 (DC1) and bgw2 (DC2).

configure
vxlan multi-site
   border-gateway ebgp
   local-vtep-ip 10.255.1.100
!
router bgp 65001
   neighbor 192.168.100.2 remote-as 65002
   !
   address-family evpn
      neighbor 192.168.100.2 activate
      neighbor 192.168.100.2 domain remote

configure
vxlan multi-site
   border-gateway ebgp
   local-vtep-ip 10.255.2.100
!
router bgp 65002
   neighbor 192.168.100.1 remote-as 65001
   !
   address-family evpn
      neighbor 192.168.100.1 activate
      neighbor 192.168.100.1 domain remote

Step 2 · Multi-Site Verification

Verify Inter-Site EVPN peering status on bgw1:

docker exec -i clab-evpn-datacenter-lab-spine1 Cli -p 15 <<'EOF'
enable
show bgp evpn summary
EOF

✅ DONE when inter-site eBGP EVPN session between bgw1 and bgw2 shows Established.

Clean up

sudo containerlab destroy -t topology.clab.yml