Hitless migration of interconnected data center networks for network virtualization overlay using gateways

A first network device comprising:

• one or more processors;
• one or more network interfaces;
• and
• at least one memory storing instructions that, as a result of execution by the one or more processors, cause the first network device to:
• operate in a first mode in which the first network device is configured to process network traffic according to a first communication protocol and to process network traffic according to a second communication protocol;
• receive, from a second network device, first routing information regarding a first route associated with a first host device in a first data center, the first route including an address of the second network device formatted according to the second communication protocol;
• install the first route in a routing table stored in the at least one memory of the first network device;
• generate a second route that includes an identifier of the first network device formatted according to the first communication protocol;
• export the second route to a third network device over one or more external networks;
• receive, from the third network device, an encapsulated data packet having an overlay that includes the identifier;
• replace, in the overlay, the identifier with the address based on the first route stored in the routing table of the first network device;
• and
• send a re-encapsulated data packet to the second network device.

One or more non-transitory computer-readable media storing instructions that, as a result of execution by one or more processors, cause the one or more processors to:

• enable operation of a first network device in a first data center in a first mode in which the first network device is configured to process network traffic according to a first communication protocol and to process network traffic according to a second communication protocol;
• receive, from a second network device in the first data center, first routing information regarding a first route associated with a first host device in the first data center;
• generate, based on the first route, a second route that includes a first address of the first network device formatted according to a first communication protocol;
• export the second route to a third network device in a second data center;
• receive, from the third network device, an encapsulated data packet having a first overlay that includes the initial address;
• and
• decapsulate and send a re-encapsulated data packet to the second network device, the re-encapsulated data packet having a second overlay that includes a second address, wherein the first address is formatted according to the first communication protocol and the second address is formatted according to a second communication protocol.