We have several WAN connections that are point to point, but the carrier provides an Ethernet handoff to our equipment. One problem with this setup is that if the long haul portion of the circuit goes down our router interface stays up. We use a routing protocol to route around the down circuit, but since our router interface stays up we can not easily detect that the circuit is down.
Is there anyway to have the Ethernet interfaces go down when they can no longer reach the other end of the connection? Would a GRE tunnel or something similar over the connection work for this and then we can detect when the tunnel goes down instead? If so, what would be the pros and cons of doing this.