# rank: switch-group id, switch id, port number (this line will be skipped)
0: 0 0 -1
1: 0 0 -1
2: 0 0 -1
3: 0 0 -1
4: 0 1 -1
5: 0 1 -1
6: 0 1 -1
7: 0 1 -1
8: 1 2 -1
9: 1 2 -1
10: 1 2 -1
11: 1 2 -1
12: 1 3 -1
13: 1 3 -1
14: 1 3 -1
15: 1 3 -1
