Allied Telesis AT-FS238a/2 - Manual (Page 21)

AT-FS238a/x and AT-FS238b/x Series Installation Guide
9
Duplex Mode
The fiber optic port on the bridging converter can operate in half- or full-
duplex mode. You must set the duplex mode manually using the DIP switches
on the back of the unit.
Mode Selection Button
Link Test
The link test is a fast and easy way for you to test the connections between the
bridging converter ports and the end-nodes that are connected to the ports. If
a network problem occurs, you can perform a link test to determine which port
is experiencing a problem, and be able to focus your troubleshooting efforts on
the cable and end-node where the problem resides.
A link test is performed when the Mode Selection button is toggled until the
LNK LED is green.
Note
Performing a link test does not interfere with a bridging converter’s
ability to pass network traffic.
MissingLink
The MissingLink feature enables the fiber optic ports on the bridging
converter to pass the “Link” status of their connections to each other. When
the bridging converter detects a problem with one of the ports, such as the loss
of connection to an end-node, the bridging converter shuts down the
connection to the other port, thus notifying the end-node that the connection
has been lost.
For example, if the network twisted pair cable to the 10Base-T/100Base-TX
port on the bridging converter were to fail, the unit would respond by dropping
the link on the 100Base-FX fiber optic port. In this way, the bridging
converter notifies the end-node connected to the fiber optic port that the
connection on the twisted pair port has been lost. If the failure had started
with the fiber optic cabling, the unit would drop the link to the twisted pair
port.
The value to this type of network monitoring and fault notification is that
some devices 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 end-node or send out a trap to a network
management station, and so alert the network administrator of the problem.