ASA Active/Standby with BDI/BVI
I see a lot of ASA designs and they are typically flanked with switches. One of the reasons for this is that the failover requirements typically dictate that the devices to be layer 2 adjacent in each security zone. There is obviously the requirement to be L3 directly connected to their next hop. The result of this requirement that an ASA can’t typically be directly connected directly to an L3 only device and it is often the case that a switch is sandwiched between the FW and the next L3 device.
This article is meant to outline a possible work around with IOS and IOS-XE based routers to provide the L2 two adjacency using inherit L2 features. Readers may use these sample configurations to build out there own labs and more fully validate the applicability the their environment.
TL;DR–BDI and BVI allow ASA A/S to function properly in my testing.
The Topology
Below is the topology that used for validating this. In a real world scenario it is less likely that routers would be the connection point on all interfaces. The reason I positioned them here is to demonstrate both IOS and IOS-XE techniques in the same lab.