In one embodiment, a method includes establishing a control channel across a wide area network (WAN) from a first gateway that has a first public internetwork layer (L3) address to a second gateway that has a second public L3 address. Each gateway connects a local area network (LAN) to the WAN. Negotiations over the control channel establish a first set of private L3 addresses for the first LAN and a non-overlapping second set for the second LAN. A different address from the first set is provided for each different node in the first LAN. A discovery packet is received from the first LAN. The discovery packet is encapsulated in a tunnel packet directed to the second public L3 address. The tunnel packet is sent over the WAN to the second gateway which extracts the discovery packet. The second gateway sends the discovery packet over the second LAN.