Our current scenario is, we have a Router-A cisco 2821 that is connected with two ISPs in multihoming configuration through BGP, so that if one ISP gets down the other takes over, we are receiving just a default route from our ISPs, and PIX 515E have a default static router for internet to router-A. below is the picture of our current scenario
Currently we are planning to add some redundancy in our network and at first stage we want to have another router Router -B parallel to Router-A as shown below.
My Question is
1. if I configure two static routes in PIX 515E so that Router-A is my prefered route to Internet, but if ISP-1 gets down how will PIX come to know that it should forward the traffic to Router-B ?
2. Should I configure dynamic routing protocol like OSPF in between PIX, Router-A and Router-B in such a way that Router-A is my prefered router to Internet? in this case if ISP-1 gets down how OSPF will come to know that ISP-1 is down and now it should change its default route from Router-A to Router-B.