I am planning on getting rid of packets going to unrouted nonexistent rfc1918 networks in our DC environment going into internet facing firewall from our core/distribution switch via default route. I am thinking on setting a bunch of rfc1918 static routes to Null0 on the core/distro switches so they will kill all the packets destined to unused rfc1918 networks into Null0. Wondering if that would be a good solution to this.
I am not sure quite what you have in mind when you talk about a bunch of rfc1918 static routes. I could see doing a route for 10.0.0.0 range, for 172.16.0.0 range, and for 192.168.0.0 range. Is 3 a bunch? If you had more in mind what would they be?
If you do static routes to Null0 for the summarized spaces then it would allow routing to any private addresses used inside your network to work since they should have more specific entries in your routing table and it would discard traffic with destination addresses in private address space. Be aware that if you have any site to site VPN tunnels from the firewall or any address translations on the firewall that use private addresses that your plan may very well have negative consequences for them.