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Precautions in using loop detection function
Disable loop detection at upstream port(s)
If a network is consisted of only Switching Hub equipped with loop detection
function, an upstream Switching Hub may detect on ahead and block a loop
occurred in a downstream Switching Hub. This may block all communications to
the downstream Switching Hub(s).
To minimize the communication failure by loop detection, disable the loop
detection function of the upstream Switching Hub so that only a port of the
Switching Hub causing loop will be blocked. You need to examine this type of
network configuration and Switching Hub settings.
Fig. 2 Precautions in using loop detection function
Downstream
Switching Hub 1
Upstream Switching Hub
PC 1
PC 2
PC 3
(1)
[Occurrence conditions]
(1) Communications between PC 1 and PC 2, and between PC 1 and PC 3
are OK.
(2) A loop occurs in the downstream Switching Hub 2.
(3) The upstream Switching Hub detects the loop first, and shuts down the
uplink port to downstream Switching Hub 2.
(Normally, only a port having loop connection is shut down.)
(4) The uplink port to downstream Switching Hub 2 is linked down, and
communications to all other Switching Hubs are blocked.
Downstream
Switching Hub 2
(2)
(3)
(4)