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Diagnostic Functions
If the TDM system is Out of Sync, you will be allowed to initiate a User Data Test at the Node S
supervisory port CRT interface, with data origin and loopback point at Node S. This test can de-
termine if the Out of Sync problem is caused at Node S, or due to failures elsewhere in the system
(see the following paragraphs).
FIGURE 8-1. AGGREGATE USER DATA LOOPBACK PATHS (NODE M DATA ORIGIN)
The User Data Test may be applied in two ways. If customer test equipment is connected to a
channel, test data is looped back for error analysis by the test equipment. When used with external
test equipment, the User Data Test evaluates the operation of the involved channel as well as
Common Set and Redundancy Control modules. This arrangement is shown in Figure 8-1.
The User Data Test may also be used without external test equipment to evaluate node operation
when the system is Out of Sync. Since the Transmit/Receive Logic Plus module always attempts
to maintain synchronization with the opposite-end multiplexer, it will synchronize on the data
looped back to it during the User Data Test (even if no channels are operating). If the card fails
to achieve synchronization during the loopback, the system remains Out of Sync. This is an indi-
cation that the failure is located at the node where the test is being run.
If the alarm scan reports:
IN SYNC
after the loopback is put into effect, then the TDM unit at that node is operating properly; the Out
of Sync condition is due to failures at the opposite-end node, or in the aggregate link connecting
nodes. Follow these steps to perform an Aggregate User Data Test Loopback:
NOTE
When initiated, the Aggregate User Data Test disrupts all normal
TDM data traffic.
8-5
036R660-000, Issue 10
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