I met a situation. In order to simplify it, I imitate it with the following diagram
there is a vpn tunnel between Pix1 and Pix3. R4 has two paths to reach R5. One is the vpn and another is through R6. The result is the traffic goes through R6(R5, R6 and R4 are configured with eigrp) and the vpn is just backup.
The question is how to configure the balance in order that the traffic goes through the vpn and R6 is used as backup ? As we know, AD, metric and cost etc decide the path selection. in this situation, what factor affect the path selection ? thank you.