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Testing LTPH-UM-1031-03, Issue 3
48 September 12, 2003 H4TU-C-319 List 1
Manual Loopback Session
A manual loopback session allows you to select any one of the HDSL4 loopbacks listed in Table 16 on page 51
with the exception of SmartJack loopbacks, which can only be issued by inband commands.
Setting the Loopback Time-Out Option (LBTO)
Before initiating a loopback session, verify that the Loopback Time-Out parameter is set to the desired setting.
1 Use the MODE and SEL pushbuttons as described in “Setting Options through MODE and SEL” on page 10.
(The loopback time-out parameter is also user-selectable from the Config Menu, Standard Options screen
when using a maintenance terminal.)
2 Select the desired setting:
• NONE (time-out disabled)
• 20 minutes
• 60 minutes
• 120 minutes
• 8 hr
• 24 hr
Activating Manual Loopback Mode
To initiate a manual loopback session:
1 Press both the MODE and SEL pushbuttons on the front panel for at least 3 seconds. The following message
appears on the front-panel display:
MAN LPBK NLO? (XXXX indicates loopback choices)
2 Press SEL to activate NLOC. The display changes to MAN LPBK NLOC.
3 Press MODE to advance to the next available loopback:
• NDx? = Doubler 1 or Doubler 2, if H4D is available
• NRE? = NREM
• CRE? = CREM
With the exception of SmartJack, any of the HDSL4 loopbacks can be executed using the MODE
and SEL pushbuttons.
When executing a manual loopback session using the MODE and SEL pushbuttons:
• The next loopback option can be displayed by pressing the MODE pushbutton, however, the
previously activated loopback remains active until the SEL pushbutton is pressed, which
activates the new loopback.
• If neither pushbutton is pressed for a period of 30 seconds and no loopback is in effect, the
manual loopback session terminates, and the display returns to normal mode.
• If any loopback is in effect, the 30-second time-out is inhibited. The active loopback and the
manual loopback sessions continue until the loopback times out in accordance with the
LBTO setting.
• If there is an active loopback, pressing the MODE and SEL pushbuttons for 3 or more
seconds terminates any active loopback, ends the manual loopback session, and returns the
display to normal mode.