12-2
Cisco ONS 15600 SDH Reference Manual, Release 9.0
78-18400-01
Chapter 12 Performance Monitoring
12.2 Intermediate-Path Performance Monitoring
During the accumulation cycle, if the current value of a performance monitoring parameter reaches or
exceeds its corresponding threshold value, a threshold crossing alert (TCA) is generated by the node and
sent to CTC. TCAs provide early detection of performance degradation. When a threshold is crossed,
the node continues to count the errors during a given accumulation period. If 0 is entered as the threshold
value, the performance monitoring parameter is disabled.
Change the threshold if the default value does not satisfy your error monitoring needs. For example,
customers with a critical VC3 installed for on-demand emergency calls must guarantee the best quality
of service on the line; therefore, they lower all thresholds so that the slightest error raises a TCA.
12.2 Intermediate-Path Performance Monitoring
Intermediate-path performance monitoring (IPPM) allows a nonterminating node to transparently
monitor a constituent channel of an incoming transmission signal. ONS 15600 SDH networks only use
line terminating equipment (LTE), not path terminating equipment (PTE). The following cards are LTE
equipment in the ONS 15600 SDH system:
•
OC48/STM16 SR/SH 16 Port 1310
•
OC48/STM16 LR/LH 16 Port 1550
•
OC192/STM64 SR/SH 4 Port 1310
•
OC192/STM64 LR/LH 4 Port 1550
•
OC192LR/STM64 4 Port ITU C-Band
IPPM enables LTE cards to monitor near-end path PM data on individual virtual containers (VC)
payloads. After enabling IPPM on provisioned VC3 or VC4 ports, service providers can monitor large
amounts of VC traffic through intermediate nodes, thus making troubleshooting and maintenance
activities more efficient.
IPPM occurs only on VC4 paths that have IPPM enabled, and TCAs are raised only for PM parameters
on the selected IPPM paths. The monitored IPPMs are VC4 HP-EB, VC4 HP-ES, VC4 HP-SES,
VC4 HP-UAS, and VC4 HP-BBE. The following ratio parameters are provided: VC4 HP-BBER,
VC4 HP-ESR, and VC4 HP-SESR. To enable IPPM, refer to the
Cisco ONS 15600 SDH Procedure
Guide
.
The ONS 15600 SDH performs IPPM by examining the overhead in the monitored path and reading all
of the near-end path performance monitoring parameters in the incoming transmission direction. The
IPPM process allows the path overhead to pass bidirectionally through the node completely unaltered.
For detailed information about specific performance monitoring parameters, see the
“12.4 Performance-Monitoring Parameter Definitions” section on page 12-3
.
12.3 Pointer Justification Count
Pointers are used to compensate for frequency and phase variations. Pointer justification counts indicate
timing differences on SDH networks. When a network is not synchronized, frequency and phase
variations occur on the transported signal. Excessive frequency and phase variations can cause
terminating equipment to slip. These variations also cause slips at the SDH and plesiosynchronous
digital hierarchy (PDH) boundaries.
