US Patent 7953103 Multi-homing using controlled route leakage at a backup service provider

In one embodiment, a network node of a secondary network receives a message from a multi-homed network. The message includes a block of network addresses allocated to the multi-homed network. It is determined that a primary network has advertised an aggregated route including the multi-homed network's allocated block of network addresses. Advertisements of the multi-homed network's allocated block of network addresses are suppressed, after a determination that the primary network has advertised an aggregated route including the multi-homed network's allocated block of network addresses. It may be later be determined that the multi-homed network has lost network connectivity via the primary network. Advertisements of the multi-homed network's allocated block of network addresses are unsuppressed, after a determination that the multi-homed network has lost network connectivity via the primary network.