We have a requirement from our customer to have a fully redundant path to the outside internet.  The servers within our enclave will need to be able be routed to by an external enclave.  The switches with the network are setup as the primary and secondary default gateways for the internal network.  How can we advertise the sole network we have and have each piece of equipment within the chain paying attention to failures ahead so that the route back can be poisoned and traffic be diverted to the secondary path?  I don't have a issue if the solution brings in load sharing, unfortunately I can't solve a way for a windows computer to use a secondary default gateway if the first is still working.  Thanks for your help.