I need help in verifying the legitimacy of a design for a multihomed Internet-facing site. I have attached a Layer 3 diagram that has four routers with red labels and a fault-tolerant ASA 5515 (two ASAs configured in failover). I have also attached the relevant configuration for each device. I need someone to verify that this design will work as expected.
I plan on having two ISPs that I will advertise my public /24 subnet to. Each ISP will advertise only a default route into my AS. I want to achieve fault tolerance at all levels and avoid routing loops and "black holes". I present two optional sections in the configs that pertain to load balancing. One option is to use the round robin load balancing feature in the ASA to balance between both outbound routes. The other option, mentioned in the edge configs, uses the weighted GLBP load balancing, allowing for weights, simpler ASA operation, and the use of a single, virtual gateway IP. I'm liking this design over the ASA load balancer method. Any opinions on this decision? I also plan on running iBGP between the edge routers.
If it needs more explaining, let me know.