Introduction to Virtual Extensible LAN (VXLAN)

Hello Patrick

Remember that the purpose of VXLANs is not only to surpass the limitation of 4K VLAN IDs, but also to add flexibility to deployments, allowing for the simpler spanning of VLANs across sites. When there is no need to expand beyond that 4K limit, typical customer deployments will use a 1:1 mapping of available VLANs for simplicity.

However, when scalability to reach beyond this limit is needed, then it is possible to do so by assigning the same VLAN IDs to multiple unique VNIs found on different VTEPs within the fabric. So for example, you could have

  • VLAN 456 mapped to VNI 123 using a subnet of
  • VLAN 456 mapped to VNI 321 using a subnet of

The same VLAN ID is used, but on different VNIs. You can theoretically have 16 million VNIs each having 4000+ VLANs mapped to them.

Typically, you would have one VNI on a single physical switch, so you do have a limitation of 4k per physical device, but that is typically not a limiting factor.

I hope this has been helpful!