Checklist and troubleshooting

Checklist

• Underlay first: every leaf loopback reachable from every other, over every path.
• EVPN address family on every session; advertise-all-vni on the leaves.
• Spines with eBGP: attribute-unchanged next-hop for EVPN.
• VXLAN interfaces sourced from the loopback, with nolearning, attached to the VNI's bridge.
• Route targets explicit in mixed-vendor fabrics.
• MTU: VXLAN adds 50 bytes. Raise the underlay MTU (9000 is common) so 1500-byte host frames fit.

When it doesn't work

Symptom	Look at	Usual cause
No EVPN routes at all	show bgp l2vpn evpn summary	Address family not activated, or advertise-all-vni missing
VNI missing from show evpn vni	The kernel: ip -d link show vxlan100	VXLAN interface down or not in a bridge
Remote MACs present, no traffic	Underlay ping between loopbacks	VTEP addresses not reachable
Traffic goes via the spine, or not at all	Next hop on received EVPN routes	Spine rewrote the next hop
Routes received but not imported	show bgp l2vpn evpn vni <n>	Route targets don't match
Small packets work, big ones don't	Underlay MTU	50 bytes of VXLAN overhead