Notes when using the Loop detection and blocking function - Disable the function
on the upstream switch
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If you configure a network only with switches having the Loop detection and
blocking function, the upstream switch may detect a loop occurring on the down
-
stream switch first depending on the condition. Then, all communications to the
downstream switch may be blocked.
To minimize the impact of communication blocks caused by loop detection, the
Loop detection and blocking function needs to be disabled on the upstream
switch. Then, network configuration and switch settings need to be changed to
block only the port having a loop on the switch.
Upstream switch
Downstream
switch 1
Downstream
switch 2
PC 1
PC 2
PC 3
(1)
(4)
(3)
(2)
[Occurrence conditions]
(1) Communication is taking place between PC 1 and PC 2, and
between PC 1 and PC 3.
(2) A loop occurs on downstream switch 2.
(3) The upstream switch detects the loop first and blocks the uplink
port on downstream switch 2. (Normally, only the loop-con
-
nected port is blocked.)
(4) The uplink port on downstream switch 2 is linked down, and all
communication to other switches is blocked.
Figure 5-2 Notes when using the Loop detection and blocking function