Allied Telesis AT-8100 Series - Manual (Page 518)

Chapter 31: Group Link Control
518
Only one group has to be true for the switch to shut down the ports of the
trunk. If, for instance, port 8 loses connectivity, making group 2 true, the
switch shuts down ports 7 and 9. When connectivity is restored on port 8,
it enables ports 7 and 9 again.
In this example, the primary and backup trunks have four links each.
Figure 113. Group Link Control Example 7
If you want switch 3 to shut down the primary trunk if two links are lost, you
create six groups to cover all of the possible combinations. The groups are
listed in Table 50 on page 519. 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 makes group 5
true, causing the switch to disable ports 7 and 9, which shuts down the
trunk. If a link is reestablished on either port 8 or 10, the switch activates
ports 7 and 9 again.
3 9 7, 8
Table 49. Link Control Groups on Switch 3 in Example 6
Link Control
Group
Upstream Port Downstream Ports