Allied Telesis AT-S47 - Manual (Page 60)

Section II: Menu Interface
60
Overview
The Missing Link feature of the AT-WD1008 unit enables the
multiplexers to pass the “Link” status of their connections to each other.
If a multiplexer detects a problem with one of the ports, such as the loss
of connection on a GBIC module, the multiplexer passes the change in
link status to the other multiplexer which shuts down the connection to
the corresponding port, thus notifying the end-node connected to the
port that the connection has been lost.
For instance, if there is the loss of connection on the GBIC module in CH1
on the local multiplexer, the remote multiplexer drops the link on the
GBIC module in CH5, as shown in the illustration below.
X
LOCAL MULTIPLEXER
CH5 CH6 CH7 CH8
WEST
CH1 CH2 CH3 CH4
Switch
X
REMOTE MULTIPLEXER
Failure of fiber cable
Multiplexer drops connection
CH5 CH6 CH7 CH8
WEST
CH1 CH2 CH3 CH4
EAST
Switch
EAST