Allied Telesis AT-FS970M Series - Manual (Page 491)

AT-FS970M Switch Command Line User’s Guide
491
In the first diagram a server with two teamed network adapter cards is
connected to different switches, with the active link to switch 3. If there is a
failure on the active link, the server can detect it directly and would
respond by automatically transferring the traffic to the redundant network
interface and the secondary path, which leads to switch 4.
Figure 102. Group Link Control Example 1
But if the failure occurs further upstream between switches 1 and 3, as
shown in Figure 103 on page 492, the server, unaware of the problem,
loses connectivity to the network. It continues to transmit packets to switch
3, which discards the packets.