Adaptive traffic routing in a software-defined wide area network

1. A networking device, comprising:

processing circuitry; and

memory including instructions that, when executed by the processing circuitry, cause the networking device to:

receive, from a branch gateway (BG), an indication that the BG has joined a wide area network (WAN);

assign, based in part on first load information of a first virtual internet gateway (VIG) and second load information of a second VIG, the first VIG as a primary VIG for the BG;

transmit, to the first VIG, a first redistribution cost; and

transmit, to the second VIG, a second redistribution cost greater than the first redistribution cost;

receive, from a second BG, an indication that the second BG has joined the WAN;

assign, based in part on the first load information and the second load information, the second VIG as a primary VIG for the second BG;

transmit, to the second VIG, a third redistribution cost; and

transmit, to the first VIG, a fourth redistribution cost greater than the third redistribution cost; and

assign the first VIG as a secondary VIG for the second BG, wherein a third route passes between the second VIG and the second BG, and a fourth route passes between the first VIG and the second BG, and wherein the third redistribution cost and the fourth redistribution cost indicate that packets addressed to pass addressed to pass between the BG and one of the first VIG and the second VIG should preferably be routed through the second route.

2. The networking device of claim 1 , wherein the instructions further cause the networking device to assign the second VIG as a secondary VIG for the BG.

3. The networking device of claim 2 , wherein a first route is established that passes between the first VIG and the BG, and a second route is established that passes between the second VIG and the BG.

4. The networking device of claim 3 , wherein the first redistribution cost and the second redistribution cost indicate that packets addressed to pass between the BG and one of the first VIG and the second VIG should preferably be routed through the first route.

5. The networking device of claim 1 , wherein the first VIG and the second VIG are OSPF neighbors to a core router of a core site local area network (LAN).

6. A wide area network (WAN), comprising:

a first virtual internet gateway (VIG);

a second VIG;

a branch gateway (BG); and

a network orchestrator to:

receive, from the BG, an indication that the BG has joined the WAN;

determine a first load factor for the first VIG based on load information of the first VIG;

determine a second load factor for the second VIG based on load information of the second VIG;

select a primary VIG and a secondary VIG for the BG based, in part, on the first load factor and the second load factor;

transmit, to the primary VIG, a first redistribution cost;

transmit, to the secondary VIG, a second redistribution cost, greater than the first redistribution cost;

receive, from a second BG, an indication that the second BG has joined the WAN;

determine an updated first load factor for the first VIG based on updated load information of the first VIG;

determine an updated second load factor for the second VIG based on updated load information of the second VIG;

select a primary VIG and secondary VIG for the second BG based, in part, on the updated first load factor and the updated second load factor;

transmit, to the primary VIG for the second BG, a third redistribution cost; and

transmit, to the secondary VIG for the second BG, a fourth redistribution cost greater than the third redistribution cost.

7. The WAN of claim 6 , wherein selecting the primary VIG for the BG is based, in part, on whether a skew between the first VIG and the second VIG is greater than a skew threshold.

8. The WAN of claim 6 , wherein a first route passes between the BG and the primary VIG and a second route passes between the BG and a secondary VIG, and

wherein the first redistribution cost and the second redistribution cost indicate that packets addressed to pass between the BG and one of the primary VIG and the secondary VIG should preferably be routed through the first route.

9. The WAN of claim 6 , wherein a third route passes between the second BG and the primary VIG for the second BG, and a fourth route passes between the second BG and the secondary VIG for the second BG.

10. The WAN of claim 6 , wherein the primary VIG for the BG is the first VIG and the primary VIG for the second BG is the second VIG.