Allied Telesis AT-S63 - Manual (Page 196)

Chapter 16: Group Link Control
196 Section II: Advanced Operations
In this example the primary and backup trunks have four links each.
Figure 24. Group Link Control Example 7
If you wanted switch 3 to shutdown the primary trunk if any two links were
lost, you would need to create six groups to cover all of the possible
combinations. The groups are listed in Table 59. As mentioned previously,
only one of the groups has to be true for the switch to disable the
remaining ports in the trunk. For instance, a loss of connectivity on ports 8
and 10 would make group 5 true, causing the switch to disable ports 7 and
9, which would shut down the trunk. If a link is reestablished on either port
8 or 10, the switch would activate ports 7 and 9 again.
Switch 1
Network
Switch 3
Switch 2
Switch 4
Ports 7, 8, 9, 10
Table 59. Link Control Groups on Switch 3 in Example 7
Link Control
Group
Upstream
Ports
Downstream
Ports
1 7, 8 9, 10
2 8, 9 7, 10
3 9, 10 7, 8
4 7, 9 8, 10
5 8, 10 7, 9
6 7, 10 8, 9