Verilink DIU 2130 (880-503297-001) Product Manual - Manual (Page 45)

Troubleshooting
Verilink 4-3
When a data channel loopback is activated, the incoming channel
data from the network is looped back toward the far-end. This path
allows end-to-end channel testing of the data circuit through the
network and associated DIU and CSU at each end.
Figure 4-1 DIU 2130 Data Channel Loopbacks
The DIU data channel loopback can be activated and deactivated on
either data channel. When this loopback is activated, only the
selected data channel is tested. The other data channel continues
to operate normally and transmission service is not affected.
V.54 Data Channel
Loopbacks
The V.54 data channel loopbacks are identical to the loopbacks
shown in
Figure 4-1 above; however, they can be activated by the
Data Terminal Equipment connected to the DIU 2130’s Data
Interface Module (DIM). The three V.54 leads used to activate these
loopbacks are:
• LL
—activates the data channel loopbacks on the DIU 2130 at
the local node (the node to which the DTE sending LL is
connected).
• RL
—activates the data channel loopbacks on the DIU 2130 on
the far-end of the network connection.
• TM
—is set high by the DIU 2130 upon successfully activating
LL or RL to notify the DTE of its current state.
Once the DTE sets LL or RL low, the DIU 2130 will deactivate the
data channel loopbacks and return to normal transmitting state.
Interpreting Alarms
The alarm buffer displays the following information about alarms
(This information may vary depending on the controller module
and management method used):
• Whenever the system powers up and any module does a self-
test
• Power is lost from one of the redundant power supplies
• A default or user-designated threshold is exceeded
DATA
EQ
DRVR,
RCVR,
&
INTF
XMT
RCV
TO/FROM
NETWORK
DIU 2130
MUX &
DEMUX NCC
OR
TAC
DATA CHANNEL
LOOPBACKS
(DATA
BUS)