Establish EVPN

60 minLabConfigurationCorrelationVirtualOpen-source

Turn on the control plane: bring up the loopback-to-loopback BGP session, activate the l2vpn evpn address family, advertise the relevant routes, and confirm the EVPN RIB and remote-VTEP information appear on both leaves. After this lab the directory exists — hosts can find each other.

Safety: Caution

May change state — take a snapshot first.

clear bgp and session config changes flap the control plane — treat as disruptive, work from 'vxlan-configured'.

Two-leaf VXLAN lab (Host1—Leaf1—underlay—Leaf2—Host2)

  Host1 (Linux)                                   Host2 (Linux)
  10.10.10.11/24                                  10.10.10.12/24
      │ eth1                                           eth1 │
      │                                                     │
  ┌───┴────────┐        virtual underlay          ┌────────┴───┐
  │  Leaf1     │  Ethernet0  ── p2p ──  Ethernet0  │  Leaf2     │
  │  SONiC-VS  │◀───────── routed IP fabric ──────▶│  SONiC-VS  │
  │  Lo0 =     │        (BGP, ECMP-capable)        │  Lo0 =     │
  │  10.0.0.1  │                                   │  10.0.0.2  │
  └────────────┘                                   └────────────┘
   access: EthernetX (VLAN 10 ↔ VNI 10010)   access: EthernetX (VLAN 10 ↔ VNI 10010)

Objective

• Establish the overlay BGP session between loopbacks (multihop if needed).
• Activate the l2vpn evpn address family and enable EVPN for the VNI.
• Inspect the EVPN RIB and confirm remote VTEP information.
• Correlate a locally learned MAC to its type-2 advertisement.

Starting state

• VXLAN tunnel + VLAN-VNI map present, but no EVPN session and empty remote MAC/VTEP tables.

Prerequisites: Lab 4.2 complete ('vxlan-configured' snapshot). · Underlay loopbacks reachable (Lab 4.1).

Tasks

1
Bring up the overlay (loopback) BGP session
The EVPN session is separate from the underlay session and typically peers loopback-to-loopback.
FRR / vtysh
```
vtysh
```
FRR / vtysh
```
configure terminal
```
FRR / vtysh
```
router bgp 65001
```
FRR / vtyshpeer the remote loopback
```
 neighbor 10.0.0.2 remote-as 65002
```
FRR / vtysh
```
 neighbor 10.0.0.2 update-source Loopback0
```
FRR / vtyshif eBGP over loopbacks
```
 neighbor 10.0.0.2 ebgp-multihop 3
```
Expected:
- A second BGP session (overlay) reaches Established, distinct from the underlay session.
What happened internally: Rung 5 of the ladder. The overlay and underlay sessions fail independently — keep them mentally separate.
2
Activate the l2vpn evpn address family
FRR / vtysh
```
 address-family l2vpn evpn
```
FRR / vtysh
```
  neighbor 10.0.0.2 activate
```
FRR / vtyshadvertise locally configured VNIs
```
  advertise-all-vni
```
FRR / vtysh
```
end
```
Expected:
- EVPN AF active with the neighbor; local VNIs advertised.
What happened internally: This is where type-3 (IMET) routes get originated so BUM replication works, and type-2 routes will follow as MACs are learned.
3
Inspect the EVPN RIB and remote VTEP info
FRR / vtysh
```
vtysh -c 'show bgp l2vpn evpn summary'
```
FRR / vtyshall route types
```
vtysh -c 'show bgp l2vpn evpn'
```
FRR / vtysh
```
vtysh -c 'show evpn vni'
```
SONiC CLI
```
show vxlan remotevni
```
Expected:
- EVPN session Established; type-3 routes for the VNI present; remote VTEP (remote loopback) learned in show vxlan remotevni.
What happened internally: Rungs 5–7. Remote VTEP now known even before any host traffic — that is the type-3/IMET machinery.
4
Correlate a local MAC to its advertisement
Generate one frame from Host1, then watch the MAC appear locally and as a type-2 route.
Linuxfrom Host1 → Host2 (may need ARP first)
```
ping -c1 10.10.10.12
```
SONiC CLILeaf1: local learn of Host1 MAC
```
show mac
```
FRR / vtyshtype-2 advertisement
```
vtysh -c 'show bgp l2vpn evpn route type macip'
```
Expected:
- Host1's MAC learned locally on Leaf1 and present as a type-2 route; on Leaf2 the same MAC appears as remote behind Leaf1's VTEP.
What happened internally: This is the control-plane half of Lab 4.4's correlation: local learn → type-2 originate → remote import.

Troubleshooting branches

If: EVPN summary shows session down

Then: Overlay session uses loopbacks + update-source; underlay must already route those loopbacks. Check multihop for eBGP.

If: Session up but no type-2/type-3 routes

Then: advertise-all-vni present? VNI locally configured? This is the 'session up, route absent' split state — check RT/import next.

If: Remote VTEP not in show vxlan remotevni

Then: Confirm type-3 routes are being exchanged and VNIs match on both leaves.

Cleanup / rollback

Keep EVPN running — Labs 4.4–4.6 depend on it.
Snapshot each leaf as 'evpn-established'.

Lab evidence checklist

☐ Overlay EVPN session Established (distinct from underlay).
☐ type-3 routes present for the VNI; remote VTEP learned.
☐ A local MAC correlated to its type-2 advertisement.
☐ 'evpn-established' snapshot exists on each leaf.

Reflection

How did Leaf2 learn about Leaf1's VTEP before any unicast traffic flowed?
If the EVPN session were up but no type-2 routes appeared, which two causes would you check first?

Lab notes & observations