Allied Telesis AT-MCF2012LC/1 - Manual (Page 33)

AT-MCF2012LC and AT-MCF2012LC/1 Media Converter Modules Installation Guide
33
node connected to that port of the loss of the link on the
fiber optic port.
The Link LEDs of the ports in a channel running in this
mode always operate in tandem, as shown in Table 4 on
page 26. They can be both on or off. Both Link LEDs of the
ports of a channel operating in this mode remain off until
both ports can establish a link with their networking device.
This operating mode is useful when the networking devices
connected to the ports of a channel can react to a loss of a
link on a port, such as managed Fast Ethernet switches
running SNMP or a spanning tree protocol. Conversely, the
MissingLink mode will be of little value if the networking
devices of a channel cannot react to a lost link. In the latter
scenario, it would probably be better to set a channel to the
Link Test mode, instead, during normal network operations.
Furthermore, Allied Telesis does not recommend using the
MissingLink mode when troubleshooting a network problem
that may have its roots with a link problem. The MissingLink
mode will not allow you to use the Link LEDs of the ports in
a channel to diagnose the problem. Rather, the Link Test
and the Smart MissingLink modes are more useful when
troubleshooting a link problem.
Smart
MissingLink
Mode
The Smart MissingLink mode, the third operating mode of
the media converter channels, is nearly identical in terms of
functionality to the MissingLink mode. It, too, enables the
ports of a channel to pass the “Link” status of their
connections to each other so that both ports reflect the
same link status.
The difference is that rather than completely shutting off the
transmitter of a port when its companion port in a channel
loses its link, this operating mode pulses the port’s
transmitter and blinks the port’s Link LED every second.
This signals the port’s ability to still establish a link to its
networking device and that the loss of the link originated on
the companion port in the channel.
This difference allows you to use the Link LEDs of the ports
to troubleshoot a link failure. In contrast, when a channel is
operating in the MissingLink mode you cannot use the Link
LEDs of the ports to troubleshoot a link problem because
both LEDs will be off when one port loses its link.
For a definition of the Link LEDs when a channel is
operating in this mode, refer to Table 5 on page 26.