Specifications

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Cisco ONS 15454 Installation and Operations Guide, R3.2
March 2002
Chapter 8 Performance Monitoring
Enabling Pointer Justification Count Parameters
8.4 Enabling Pointer Justification Count Parameters
Pointers are used to compensate for frequency and phase variations. Pointer justification counts indicate
timing errors on SONET networks. When a network is out of synch, jitter and wander occurs on the
transported signal. Excessive wander can cause terminating equipment to slip. It also causes slips at the
SDH and PDH boundaries.
Slips cause different effects in service. Voice service has intermittent audible clicks. Compressed voice
technology has short transmission errors or dropped calls. Fax machines lose scanned lines or experience
dropped calls. Digital video transmission has distorted pictures or frozen frames. Encryption service
loses the encryption key, which causes data to be transmitted again.
Pointers provide a way to align the phase variations in STS and VT payloads. The STS payload pointer
is located in the H1 and H2 bytes of the line overhead. Clocking differences are measured by the offset in
bytes from the pointer to the first byte of the STS synchronous payload envelope (SPE) called the J1
byte. Clocking differences that exceed the normal range of 0 to 782 can cause data loss.
Figure 8-9 shows pointer justification count parameters on the Performance Monitoring screen. You can
enable PPJC and NPJC performance monitoring parameters for LTE cards. See Table 8-4 on page 8-13
for a list of Cisco ONS 15454 LTE cards.
Figure 8-9 Reading pointer justification count parameters
There are positive (PPJC) and negative (NPJC) pointer justification count parameters. PPJC is a count
of path-detected (PPJC-Pdet) or path-generated (PPJC-Pgen) positive pointer justifications. NPJC is a
count of path-detected (NPJC-Pdet) or path-generated (NPJC-Pgen) negative pointer justifications
depending on the specific PM name.
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Performance tab Card viewPointer justification counts