Table 2 An example for RGP on a 6-by-6 regular grid.

1

Choose the busiest router from the location of (3,3), (3,4), (4,3), and (4,4)

2~4

Choose the busiest routers from the location of (2,2), (2,5), (5,2), and (5,5)

5~7

Choose the first 4 gateways at the location of (2,2), (2,5), (5,2), and (5,5) and choose the rest on the other routers with the highest traffic demand

8

36 routers are split into 4 groups. In each group, any two routers are at least 2-hops away, for example, (1,1), (1,3), (1,5), (3,2), (3,4), (3,6), (5,1), (5,3), and (5,5) are in one group. Choose the first gateway on the busiest router and choose the rest 7 gateways on the next 7 busiest routers in the same group with the first one

9

36 routers are split into 4 groups as above. Choose the first gateway on the busiest router, then choose the next 8 gateways on the other routers in the same group with the first one, and choose the rest on the other routers with the highest traffic demand