[c-nsp] Cisco uRPF/ Bogon route help

[f287cd76 at opayq.com]

Hello

Looking for help on how to configure uRPF on Cisco IOS-XE 3.13 in an asymmetric multiple ISP Edge scenario

We currently have an edge/customer router that receives a list of 'known bad' routes via BGP.   
These are re-routed to 192.0.2.1/NULL0 with a route-map. 

Today.. I only have one ISP and uRPF works fine with this syntax 
-> " ip verify unicast source reachable-via any 2699" 

I'm moving to a router with multiple  ISP and IX connections and some of our traffic is now asymmetric.
The above uRPF config didn't work and was removed. 

But I still need to drop traffic sourced from any of the above 'bad' networks. 

Suggestions on how to configure for this now?

thanks in advance 

WS