Allowing Routes to be Advertised Out

A.

In Cisco ACI, L3Outs are used to connect the ACI fabric to external networks. Ext-EPGs (External End Point Groups) are used to control the traffic flow between the ACI fabric and the external networks connected through L3Outs.

To allow routes learned from one L3Out to be advertised out another L3Out, the engineer needs to configure the Ext-EPG with the appropriate attributes. Since the engineer does not have an explicit list of all the routes that must be advertised out, but they know that they are all part of the 10.16.0.0/16 CIDR block, they need to configure the Ext-EPG to advertise the routes in this block.

The two attributes that are relevant in this scenario are Export Route Control Subnet and Aggregate Shared Routes. Export Route Control Subnet allows the Ext-EPG to advertise routes that are learned from other L3Outs. Aggregate Shared Routes allows the ACI fabric to advertise a summary route for a range of IP addresses.

Option A, "Enable Export Route Control Subnet and enable Aggregate Export," is incorrect because there is no such attribute as "Aggregate Export." The correct attribute is "Aggregate Shared Routes."

Option B, "Disable Shared Route Control Subnet and enable Aggregate Shared Routes," is incorrect because the engineer needs to enable Export Route Control Subnet to advertise the routes learned from another L3Out.

Option C, "Enable Export Route Control Subnet and disable Aggregate Shared Routes," is incorrect because the engineer needs to enable Aggregate Shared Routes to advertise the routes in the 10.16.0.0/16 CIDR block.

Therefore, the correct answer is option D, "Enable Export Route Control Subnet and enable Shared Route Control Subnet." By enabling Export Route Control Subnet, the Ext-EPG can advertise routes learned from another L3Out. By enabling Shared Route Control Subnet, the ACI fabric can advertise a summary route for the 10.16.0.0/16 CIDR block.