Allied Telesis AT-MCF12VF, SM - Manual (Page 15)

AT-MCF6xx and AT-MCF12xx 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-MCF6xx 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-3714FXL/SC Ethernet switch. If the fiber optic cable of the AT-3714FXL/
SC 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-MCF6xx unit notifies the AT-8224XL Ethernet switch that the connection
to the AT-3714FXL/SC Ethernet switch has been lost. Had the failure started
with the twisted pair cabling, the MissingLink feature would have dropped
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-3714FXL/SC 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.
Tx
Rx
Tx
Rx
Tx
Rx
7
8
9
T-LNK
F-LNK
Active
7 7
7
Connected to an
AT-8224XL Ethernet
switch
Connected to an
AT-3714FXL/SC
Ethernet switch