300-620 · Question #183
A Cisco ACI endpoint group must have its gateway address migrated out of the ACI fabric. An engineer configures EPG-TEST with a static port binding and configures the encap VLAN with the required…
The correct answer is C. L2 Unknown Unicast: Flood. To migrate an EPG's gateway address outside the ACI fabric, the bridge domain must be configured to flood L2 unknown unicast traffic. This enables ARP requests for the external gateway to be broadcast outside the fabric for proper resolution.
Question
A Cisco ACI endpoint group must have its gateway address migrated out of the ACI fabric. An engineer configures EPG-TEST with a static port binding and configures the encap VLAN with the required VLAN. Which configuration set must be used on the bridge domain to meet these requirements?
Options
- AL2 Unknown Unicast: Hardware Proxy
- BL2 Unknown Unicast: Hardware Proxy
- CL2 Unknown Unicast: Flood
- DL2 Unknown Unicast: Flood
How the community answered
(35 responses)- A9% (3)
- B6% (2)
- C71% (25)
- D14% (5)
Why each option
To migrate an EPG's gateway address outside the ACI fabric, the bridge domain must be configured to flood L2 unknown unicast traffic. This enables ARP requests for the external gateway to be broadcast outside the fabric for proper resolution.
'L2 Unknown Unicast: Hardware Proxy' means that the ACI fabric will learn endpoint MAC addresses and proxy ARPs, which is suitable when the gateway is within the ACI fabric or when ACI is expected to respond, not when an external gateway needs to directly receive flooded ARPs.
'L2 Unknown Unicast: Hardware Proxy' means that the ACI fabric will learn endpoint MAC addresses and proxy ARPs, which is suitable when the gateway is within the ACI fabric or when ACI is expected to respond, not when an external gateway needs to directly receive flooded ARPs.
When the gateway for an EPG is external to the ACI fabric, the bridge domain must be configured for 'L2 Unknown Unicast: Flood.' This setting ensures that ARP requests for the external gateway, which ACI does not know, are flooded out of the fabric on relevant ports, allowing the external gateway to receive the ARP and respond, thus enabling communication.
This option is identical to option C; assuming C is the intended correct answer, this would also be correct for the same reasons.
Concept tested: Cisco ACI external gateway L2 Unknown Unicast
Source: https://www.cisco.com/c/en/us/td/docs/dcn/aci/apic/6x/config-guide/cisco-apic-cisco-aci-configuration-guide-60x/m_configuring-bridge-domains.html
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