METRODATA LTD
WCM1100 / WCM3100 / WCM-Serial
User Manual
76-02-082 Rev J
132 of 140
When Physical Loops are disabled, only Safe loops may be applied including OAM loops
and the WAN port Remote Loop. Both of these loop types disconnect the port selected for
test from the LAN and there broadcast loops will not occur. The WAN loops are used with
the BERT tester to test the WAN port.
When Physical Loops are enabled, true physical layer loops are applied and LAN packets
are looped. This mode should not be used when connected to a LAN network and is
intended for use with LAN test equipment.
5.9.1.2 Timeout
Since loopbacks may make a unit inaccessible, a timeout allows the loop to be
automatically removed after a predefined time.
5.9.1.3 LAN / SFP Loops
The LAN and SFP ports support the following loopback options:
5.9.1.3.1 Phy Line Loop (OL)
In order to use the copper phy line loopback (loop receive back to transmit) first the PHY
LOOPs must be enabled. Once enabled, the OL loop may be selected for the PHY port.
Once selected, the loop will be applied for the configured timeout period to prevent a
permanent lock out problem occurring.
5.9.1.3.2 LAN External Loop ( XLL )
In order to use the copper External line loopback (use an external loopback plug to loop
transmit back to receive) first the PHY LOOPs must be globally enabled. Once the EXT
loop is selected an external loopback plug may be connected and the port will become
active.
5.9.1.3.3 LAN/SFP OAM-RL loop
The LAN and SFP ports can request their OAM peer device apply a loopback. This loop is
only available where OAM is enabled on the link. According to the OAM loop standard,
loop prevention is enabled as the return path is blocked internally so traffic injected into a
port will only be counted internally. Check the port counters to verify the link.
