When Cisco ACI connects to an outside Layers 2 network, where does the ACI fabric flood the STP BPDU frame?
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A. B. C. D.A.
https://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/application-centric-infrastructure/white-paper-c07-When Cisco ACI connects to an outside Layer 2 network, the ACI fabric floods the Spanning Tree Protocol (STP) Bridge Protocol Data Unit (BPDU) frame within the access encap VLAN. This is because STP BPDUs are Layer 2 multicast frames that are flooded within a VLAN, and the access encap VLAN is the VLAN that is used to encapsulate traffic going to and from the outside Layer 2 network.
In ACI, a bridge domain is a construct that defines a Layer 2 forwarding domain within the fabric. Bridge domains are used to isolate and segment traffic within the fabric, but they do not have any impact on the flooding of STP BPDUs. Therefore, option A is incorrect.
The APIC (Application Policy Infrastructure Controller) is the centralized management and policy engine of the ACI fabric. The APIC is responsible for managing the configuration of the fabric, but it does not participate in the forwarding of data traffic. Therefore, option B is also incorrect.
Option D is incorrect because STP BPDUs are not flooded between all the spine and leaf switches. Rather, they are flooded within the access encap VLAN, which is the VLAN that is used to encapsulate traffic going to and from the outside Layer 2 network.
Therefore, the correct answer is option C: within the access encap VLAN.