I basically have a 3 site triangle configuration all in OSPF area 0. Two of the sites are connected via T1 and the other link is connected via fiber. I added an OSPF cost to one of the T1's (call is backup T1) so that traffic never get routed accross it. However, I would like to force a small subset of traffic accross is this backup T1.
I know I can use route maps to accomplish this however i'd like to use OSPF in the event that the backup T1 goes down, this small subset of traffic will still be routed the alternitive route.
Is there a way in OSPF to force only a small subset of traffic to route accross a lower cost link, but will still route accross the primary T1 if the backup is down.
There are parts of your question that I do not understand very well. Let me answer what I think I do understand and if that is not the full answer that you need then perhaps you can clarify the rest for me.
There is not any way in OSPF to route a small subset of traffic differently. OSPF determines routes and all traffic is treated the same on these routes. If you need to route a small subset of traffic differently then you need Policy Based Routing, which uses route maps. In PBR you can identify certain types of traffic and can choose to forward it differently from what the routing table would do. With PBR if the next hop that you are using becomes not available then PBR will let the traffic be routed in the normal way. It sounds to me like this is a solution that comes pretty close to what I understand of your requirements.