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If you configure a network only with switches having the Loop detection and
blocking function, the upstream Switching Hub may detect a loop occurring on the
downstream Switching Hub first depending on the condition. Then, all communi
-
cations to the downstream Switching Hub 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
Switching Hub. Then, network configuration and Switching Hub settings need to
be changed to block only the port having a loop on the Switching Hub.
Figure 6-2 Notes when using the Loop detection and blocking function
Notes when using the Loop detection and blocking function - Disable the function
on the upstream Switching Hub
Upstream
Switching Hub
Downstream
Switching Hub 1
Downstream
Switching Hub 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 Switching Hub 2.
(3) The upstream Switching Hub detects the loop first and blocks
the uplink port on downstream Switching Hub 2. (Normally,
only the loop-connected port is blocked.)
(4) The uplink port on downstream Switching Hub 2 is linked
down, and all communication to other switches is blocked.
