My client has network setup as in diagram. R0 is the router connected to the LAN and R1 and R2 are connected to different service providers. Currently R1 and R2 are the routers running bgp with providers.
Traffic shifting is done from the R0 with default route pointing towards either R1 or R2 when one of the providers link goes down.
My question is that is there a way I can make sure traffic is automatically shifted from R0 without manually changing the default route. I dont want to run BGP on the R0 router connected to LAN.
What I had in mind was http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html#wp1072790, but from what you wrote, it appears you might not want to do anything on R1 or R2, but limit everything to R0.
If that's the case, Robert's suggestion of using routing tracking with SLA, might help. See http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtpbrtrk.html and http://www.cisco.com/en/US/tech/tk364/technologies_configuration_example09186a0080211f5c.shtml
How about route tracking? you track the route of your isp transfer subnet - Another idea: maybe some IP SLA with ICMP-Echos and tracking of your IP SLA?