A retail bank is building an ACI fabric and has placed the infrastructure VLAN into a tenant VLAN pool so servers can use that VLAN. What is wrong with that plan?
Select an answer to reveal the explanation.
Short Explanation
The infrastructure VLAN is the service corridor, not a tenant hallway. You keep it out of the tenant VLAN pool so servers are not placed on the VLAN the fabric uses for discovery and control. Out-of-band management is a separate network from this VLAN.
Full Explanation
ACI uses an infrastructure VLAN for fabric discovery and control traffic between APICs, leaves, and spines. That VLAN is reserved. Putting it in a tenant VLAN pool so servers can use it collides with the control VLAN, and tenant endpoints are not supposed to be addressed on it. The bank should pick a different VLAN for the tenant pool and leave the infrastructure VLAN for the fabric. The infrastructure VLAN is not a label for the out-of-band management subnet. Out-of-band management is a separate network, and it does not carry leaf-to-spine discovery. Leaves join spines over the fabric links using the infrastructure VLAN. Requiring the tenant pool to contain that VLAN reverses the rule and would spread a reserved VLAN into tenant policy. Spines forward tenant traffic inside the overlay, not by handing the infrastructure VLAN to servers. The overlap is not a required design. Caveat: the infrastructure VLAN is chosen when the fabric is set up, and changing it later is a fabric-wide event, so pick a VLAN the data center is willing to reserve. Operational check: remove the infrastructure VLAN from the tenant pool, confirm the pool deploys without that ID, and confirm servers use a tenant VLAN instead.