MAC address synchronization for multi-homing with multichassis link aggregation

A network device comprising:

• a control unit comprising one or more processors;
• an interface of the control unit configured to provide a multi-chassis link aggregation group (LAG) in an active-active multi-homing configuration with a peer network device of the network device to provide a layer two (L2) network with redundant layer three (L3) connectivity to an L3 network;
• a synchronization module of the control unit configured to receive a synchronization message that specifies an L2 address of the peer network device,
• wherein the synchronization module is configured to associate the L2 address of the peer network device with a routing instance of the network device, wherein an L2 address of the network device is also associated with the routing instance of the network device, and wherein neither the L2 address of the peer network device nor the L2 address of the network device comprises a virtual gateway L2 address shared by the network device and the peer network device,
• wherein the interface is configured to receive an L2 packet data unit (PDU) from the L2 network;
• and
• a routing instance of the control unit configured to route, when the PDU has an L2 destination address that matches the L2 address of the peer router, a layer three (L3) packet encapsulated at least in part by the PDU to the L3 network without switching the PDU toward the peer router according to the L2 destination address of the PDU.

A non-transitory computer-readable medium comprising instructions for causing one or more programmable processors to:

• establish, with a router, a multi-chassis link aggregation group (LAG) in an active-active multi-homing configuration with a peer router to provide a layer two (L2) network with redundant layer three (L3) connectivity to an L3 network;
• receive, with the router, a synchronization message that specifies an L2 address of the peer router;
• associate the L2 address of the peer router with a routing instance of the router without using a virtual gateway L2 address shared by the router and the peer router;
• receive, with the router, an L2 packet data unit (PDU) from the L2 network;
• and
• route, with the routing instance of the router when the PDU has an L2 destination address that matches the L2 address of the peer router, a layer three (L3) packet encapsulated at least in part by the PDU to an L3 network without switching the PDU toward the peer router according to the L2 destination address of the PDU.