Hello Jvetrive--are you trying to configure so that static route is advertised in the ACI fabric or to the non-ACI device that the L3Out connects to?
Static route advertisement actually very easy.
For static routes you want to advertise within the fabric, such as a dfgw or an all-zeros route, you do that on the L3Out configured node. On your L3Out you navigate to the configured node and select appropriate object. It will be named something like topology/pod-1/node-101. You will be proffered a window that allows you to see or set the properties of the border leaf, such as its RID and any loopback interfaces. If you scroll a little lower, you will see a place where you can configure static routes.
Here you can see that this border leaf has been configured with a RID of 3.0.0.101 and an all-zeros dfgw pointing towards its peer outside the fabric, which is 172.25.1.3. This dfgw gets advertised to all of the leaf switches via MP-BGP (assuming you configured it right). Like so:
pod3-aci1-leaf1# show ip route vrf White_Tree:White_Tree-2
IP Route Table for VRF "White_Tree:White_Tree-1"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%<string>' in via output denotes VRF <string>
0.0.0.0/0, ubest/mbest: 1/0
*via 172.25.1.3, eth1/15.33, [1/0], 16:21:31, static
The other way to advertise a static route is to configure it on the external L3Out network. Static routes configured on the external L3Out network are advertised to the external peer. Often, you are not advertising an all-zeros route out of the ACI fabric. Usually, you're advertising some sort of summary route that represents all of the endpoint subnets in the fabric. To do this, you navigate to the network folder under the L3Out network. Scrolling to the bottom of the properties screen you will see a listing of subnets. Here you want to add a subnet and set its scope for both "external subnet for external EPG" and "export route control subnet." For summarized routes, you must also declare a route summarization policy, even if its just the default policy (A null value in that field will not work.). Looks like this:
Here you can see an all-zeros subnet listed as "external subnets for external EPG." This configuration just tells the ACI fabric that it will get any traffic from the L3Out (that is, there is no limit to the IP range for expected traffic.). The summary route is the static route that is actually advertised. And you can see it in the border leaf's peer. Like this:
CORE-1# sh ip route 172.23.0.0 vrf BLUE
IP Route Table for VRF "BLUE"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%<string>' in via output denotes VRF <string>
172.23.0.0/16, ubest/mbest: 1/0
*via 172.25.1.2, [20/0], 00:02:16, bgp-500, external, tag 300
