Allied Telesis AT-MCF112VF, SM, LH - Manual (Page 15)

AT-MCF106xx and AT-MCF112xx Installation Guide
7
MissingLink Feature
The MissingLink
™
feature enables the twisted pair and fiber optic ports of
each channel on the media converter to pass the “Link” status of their
connections to each other. When a channel detects a problem with one of the
ports, such as the loss of connection to a node, the channel shuts down the
connection to the other port of the channel, thus notifying the node that the
connection has been lost.
For example, Figure 5 illustrates the two ports of Channel 1 on an
AT-MCF106xx unit. The twisted pair port in Channel 1 is connected to a port
on an AT-8224XL Ethernet switch and the fiber optic port is connected to an
AT-FS709FC Ethernet switch. If the fiber optic cable to the AT-FS709FC
switch experiences a failure, the MissingLink feature in the channel will
detect the problem and drop the link on the twisted pair port. In this way, the
AT-MCF106xx unit notifies the AT-8224XL Ethernet switch that the
connection to the AT-FS709FC Ethernet switch has been lost. If the failure
had started with the twisted pair cabling, the MissingLink feature would drop
the link to the fiber optic port.
Figure 5 MissingLink Example
The value to this type of network monitoring and fault notification is that
some hubs and switches can be configured to take a specific action in the event
of the loss of connection on a port. In some cases, the unit can be configured to
seek a redundant path to a disconnected node or send out a trap to a network
management station, and so alert the network administrator of the problem.
In the example above, once the AT-8224XL Ethernet switch realizes that its
connection has been lost to the media converter, and, consequently, to the
AT-FS709FC switch, the switch can send a trap to the management station,
alerting the network administrator of the problem.
Note
The MissingLink feature is disabled when you perform a link test with
the Link Test switch. Consequently, to ensure that the MissingLink
feature is enabled on the media converter, always set the Link Test
switch to the Normal position during normal network operations.
Tx
Rx
Tx
Rx
Tx
Rx
7
8
9
T-LNK
F-LNK
Active
77
7
Connected to an
AT-8224XL Ethernet Switch Connected to an
AT-FS709FC Ethernet Switch