Currently we have our secondary site running ISDN for backup in case primary and secondary mpls circuit are not available. We watching loopback of hub-site on secondary ISDN router with dialer watch list. This scenario works fine, we have flooting static route with AD of 180, as OSPF process is using default-information originate metric 200
Now, we planned to install another ISDN router on primary site dial to Hub router on same dialer interface with /24 networks.
Now requirements is:
1. if both Mpls circuit is not available, primary ISDN dial out to hub location first, if Primary ISDN is not working then Secondary ISDN dial out?
Could any one suggest what options we can use here? What should we watch on secondary ISDN router that it should dial only if primary ISDN is not working and both mpls circuit are down?