DISL C
RMST C
Note:
The Remote self-test (external loopback test) can be run through any loopback
that is external to the DTI/PRI card. The loopback can range from a loopback
connector plugged into the NTBK04 cable to a remote loopback on the far-end
DTI/PRI, or at any point in between on the DS-1 facility.
Figure 18: DTI/PRI link diagnostic and remote loopback tests on page 111 shows
the relationship between the remote loopback test and the link diagnostic test.
Figure 18: DTI/PRI link diagnostic and remote loopback tests
DTI/PRI error detection
Bit error rate
Bit error rate monitoring detects errors in transmission (see Figure 19: Bipolar violations on
page
112). There are two methods of bit error monitoring: bipolar violation tracking and Cyclic
Redundancy Check (CRC).
If the D2, D3, or D4 framing format is selected in LD 17 prompt DLOP, then bipolar violation
tracking is implemented. If the Extended Superframe (ESF) format is selected, CRC is
implemented.
Bipolar Violation tracking In a bipolar pulse stream, pulses alternate in polarity. A bipolar
violation (BPV) has occurred if, after transmission, two pulses of the same polarity are received
in succession (this could be caused by an electrical disturbance such as noise).
DTI/PRI maintenance tools
ISDN Primary Rate Interface Maintenance November 2011 111
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