Data center fabrics can operate at Layer or Layer .
Layer fabric:
- VLANs span entire fabric
- VMs migrate without IP changes
- Large broadcast domains
- Needs loop prevention like VXLAN
Layer fabric:
- Each leaf is its own subnet
- Routing handles path selection
- Smaller failure domains
- Better scalability
Common approach: Route at the leaf. Each leaf routes between server subnets. Spines run pure Layer . Use VXLAN when you need Layer adjacency.