Cisco MGX 8240 User Manual

OC3 Statistics

CHAPTER

5

Statistics

This chapter provides an overview of available statistics for troubleshooting the MGX 8240 switch.

Each OC3 performance monitoring statistic is retained for the current 15-minute interval, a history of
the last 32 15-minute intervals (8 hours), the current 24-hour period (starting and ending at midnight
GMT), and the previous 24-hour period. Along with statistics, it is also possible to verify the elapsed
time in the current 15-minute interval and the amount of 15-minute intervals currently stored (this is
relevant only during the first 8 hours of operation). The following statistics are retained:

• Section Errored Seconds

• Section Severely Errored Seconds

• Section Severely Errored Framing Seconds

• Section Coding Violations

• Line Errored Seconds

• Line Severely Errored Seconds

• Line Coding Violations

• Line Unavailable Seconds

• Line Alarm Indication Signal Seconds

• Far End Line Errored Seconds

• Far End Line Severely Errored Seconds

• Far End Line Coding Violations

• Far End Line Unavailable Seconds

• Path Errored Seconds

• Path Severely Errored Seconds

• Path Coding Violations

• Path Unavailable Seconds

• Path Alarm Indication Signal Seconds

• Far End Path Errored Seconds

• Far End Path Severely Errored Seconds

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DS3 Statistics

Chapter 5 Statistics

• Far End Path Coding Violations

• Far End Path Unavailable Seconds

Each DS3 performance monitoring statistic is retained for the current 15-minute interval, a history of the
last 32 15-minute intervals (8 hours), and the current 24-hour period (starting and ending at midnight
GMT). Along with the statistics, it is also possible to verify the elapsed time in the current 15-minute
interval and the amount of 15-minute intervals currently stored (this is relevant only during the first
8 hours of operation). The following statistics are retained:

• P-bit Errored Seconds

• P-bit Severely Errored Seconds

• P-bit Coding Violations

• Severely Errored Framing Seconds

• Line Errored

• Line Severely Errored Seconds

• Line Coding Violations

• Unavailable Seconds

• Alarm Indication Signal Seconds

• C-bit Errored Seconds (applies only to C-bit Parity line type)

• C-bit Severely Errored Seconds (applies only to C-bit Parity line type)

• C-bit Coding Violations (applies only to C-bit Parity line type)

• Far End C-bit Errored Seconds (applies only to C-bit Parity line type)

• Far End C-bit Severely Errored (applies only to C-bit Parity line type)

• Far End C-bit Coding Violations (applies only to C-bit Parity line type)

• Far End Unavailable Seconds (applies only to C-bit Parity line type)

DS1 Statistics

Note Line Errored Seconds, Line Severely Errored Seconds, and Line Coding Violationsare not

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supported directly on the MGX 8240 because the MGX 8240 does not terminate the DS1
line. This means that no performance monitoring statistics can be supported when the DS1
is not set for ESF or SF framing. Since the only means of monitoring far end performance
statistics is through the ESF Facilities Data Link, far end statistics can only be supported
when ESF framing is selected.

The following statistics are retained:

• Errored Seconds (applies only to ESF and SF framing types)

• Severely Errored Seconds (applies only to ESF and SF framing types)

• Severely Errored Framing (applies only to ESF and SF framing types)

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• Unavailable Seconds (applies only to ESF and SF framing types)

• Path Coding Violations (applies only to ESF and SF framing types)

• Alarm Indication Signal Seconds (applies only to ESF and SF framing types)

• Far End Errored Seconds (applies only to ESF framing type)

• Far End Severely Errored Seconds (applies only to ESF framing type)

• Far End Severely Errored Framing Seconds (applies only to ESF framing type)

• Far End Path Coding (applies only to ESF framing type)

• Far End Line Errored Seconds (applies only to ESF framing type)

• Far End Unavailable Seconds (applies only to ESF framing type)

• Out-of-Frame

Protocol Layer Statistics

This protocol layer statistics for the MGX 8240 are described below.

Protocol Layer Statistics

ATM

Each ATM logical port statistic is kept for the current 15-minute interval, a history of the last two
15-minute intervals (30 minutes), and the current 24-hour period (starting and ending at midnight GMT).
The ATM statistics are as follows:

• Valid Cells Ingress

• Cells Ingress discarded due to HEC Errors

• Cells Egress

Circuit Emulation Service

Circuit Emulation Service (CES) connection statistics are kept for the current 15-minute interval, a
history of the last 96 15-minute intervals (24 hours), the current and previous 24-hour period (starting
and ending at midnight GMT).

• Cells Reassembled—Number of incoming cells that were played out to the CES Service interface.

It excludes cells that were discarded for any reason, such as cells that were not used due to being
declared misinserted, or discarded while the reassembler was waiting to achieve synchronization.

• Cells with Header Errors—Cells received with AAL1 header errors detected, including those

corrected. This includes cells with both correctable and uncorrectable CRC, as well as bad parity in
the Sequence Number Protection field of the AAL1 header.

• Pointer Reframes—Number of events in which the AAL1 reassembler found that an SDT pointer is

not where it is expected, and the pointer must be reacquired. This count is only meaningful for
structured CES modules, as Unstructured CES modules do not use pointers. For Unstructured CES
connections, this count is zero. If this occurs, any received cells are dropped until the reassembly
underflows. Sequence number synchronization and valid pointer is then searched for. When sync is
reached, cells are buffered until the configured Cell Delay VariationTolerance buffer is filled.Once
filled, the buffered data is played out the CES service interface.

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Alarms

Chapter 5 Statistics

• Pointer Parity Errors—Number of events in which the AAL1 reassembler detects a parity check

failure at the point where a structured data pointer is expected. This count is only meaningful for
structured CES modules, as Unstructured CES modules do not use pointers. For Unstructured CES
connections, this count is zero.

• Sequence Errors—Number of times that the sequence number of an incoming cell causes a transition

from the Sync state to the Out of Sequence state, as defined in ITU-T I.363.1

• Lost Cells—Number of cells lost in the ATM network, as detected by the AAL1 sequence number

processing.

• Misinserted Cells—Number of AAL1 sequence violations interpreted as a misinserted cell, as

defined by ITU-T I.363.1

• Buffer Underflows —the number of times the CES reassembly buffer underflows. In the case of a

continuous underflow caused by a loss of ATM cell flow, a single buffer underflow is counted. After
an underflow occurs, data is again buffered until the configured Cell Delay Variation Tolerance
buffer is filled. Once filled, the buffered data is played out the CES service interface.

• Buffer Overflows—Number of times the CES reassembly buffer overflows. When this occurs, any

received cells are dropped until the reassembly underflows. Sequence number synchronization is
then searched for again (and structure pointers if in structured mode). When sync is reached, cells
are buffered until the configured Cell Delay Variation Tolerance buffer is filled. Once filled, the
buffered data is played out the CES service interface.

• Dropped Cells—Number of incoming cells dropped due to one of the following:

–

Misinserted cell detected

–

Loss of sequence number synchronization

–

Structured data pointer reframe

–

Buffer overflow

–

Searching for structured data pointer

–

Disabled channel

Alarms

DS1 Alarms

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This section describes the alarms on the MGX 8240.

Alarms are generated when the following conditions are detected, and cleared when the conditions clear.
LOF alarms require 2 seconds to declare and 16 seconds to clear. AIS alarms require 1.6 seconds to
declare and 10 seconds to clear. All of the following are “critical” alarms.

• Receiving AIS

• Receiving Yellow Alarm

• Loss of Frame Pointer (LOF)

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DS3 Alarms

SONET Alarms

Alarms

Alarms are generated when the following conditions are detected, and cleared when the conditions clear.
LOS and LOF alarms require 2 seconds to declare and 16 seconds to clear. AIS alarms require

1.6 seconds to declare and 10 seconds to clear. All of the following are “critical” alarms.

• Receiving AIS

• Receiving Yellow Alarm

• Not Receiving Valid Signal (LOS) (only for DS3 I/O)

• Loss of Frame Pointer (LOF)

Alarms are generated when the following conditions are detected, and cleared when the conditions clear.
Line and Path AIS, RDI, FERF, LOS, LOF, and LOP alarms require 2 seconds to declare and 16 seconds
to clear. The severity of these alarms depends on whether the line is protected using SONET APS. If one
of the APS lines is still active, these are “minor” alarms. If both lines alarm, or APS protection has been
disabled, these are “critical” alarms.

The SONET alarms are as follows:

• Receiving Path AIS

• Receiving Path Yellow Signal (RDI)

• Not Receiving Valid Signal (LOS)

• Loss of Frame Pointer (LOF)

• Receiving Line AIS

• Receiving Line Failure from Far End (FERF)

• Loss of Payload Pointer

• Signal Degrade

The APS specific alarms require 2 seconds to declare and 16 seconds to clear. The APS specific alarms
are as follows:

• APS Protection Byte Failure

• APS Channel Mismatch Failure

• APS Mode Mismatch Failure

CES Alarm Handling

This section covers how CES Service Interface alarms and loss of cells (persistent reassembly buffer
underflow) alarms are handled. Structured and unstructured CES are handled differently.

Unstructured Service Interface Alarms

In unstructured mode, any alarms received at the input of the service interface are carried through
without modification. These alarms can be optionally monitored by the MGX 8240 cards.

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Statistics

Some conditions exist when the frame is not passed through. The ATM Forum CES specification states
that the CES IWF sends cells containing all ones (an unframed AIS signal) when Loss of Signal (LOS)
is detected for the DS1. Since the MGX 8240 does not physically terminate the DS1s, LOS cannot be
detected. If an auxiliary M13 multiplexer is used to terminate the DS1, it detects the LOS and generates
an AIS signal within the DS1 toward the MGX 8240, which passes it through in cells towards the far end.

Although the MGX 8240 cannot detect DS1 LOS, it can detect the following problems:

• Containing DS3 Loss of Signal (only for DS3 I/O)

• Containing DS3 Loss of Frame

• Containing DS3 Receiving AIS

• DS1 Out-of-Frame (only applies when set to monitor the DS1 frame)

When the MGX 8240 detects one of these problems, it sends cells containing all ones toward the far end.

Structured Service Interface Alarms

When providing structured DS1 CES service, the DS1 frame is terminated on the local CES service
interface. The ATM ForumCES specificationstatesthatwhen DS1 Loss of Signal, AIS, or Out-of-Frame
is detected, the CES IWF sends cells containing Trunk Conditioning. Since the MGX 8240 chassis does
not physically terminate the DS1s, LOS cannot be detected. If an auxiliary M13 multiplexer is used to
terminate the DS1, it detects the LOS and generates an AIS signal within the DS1, towards the
MGX 8240, which detects the AIS and reacts appropriately.Although the MGX 8240 cannot detect DS1
LOS, it can detect the following problems:

• DS1 Out-of-Frame

• DS1 Receiving AIS

• Containing DS3 Loss of Signal

• Containing DS3 Loss of Frame

• Containing DS3 Receiving AIS

When the MGX 8240 detects one of these problems, it sends cells containing Trunk Conditioning
towards the far end.

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Statistics

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Each of the ATM connection statistics below is kept for the current 15-minute interval, a history of the
last two 15-minute intervals (30 minutes), and the current 24-hour period (starting and ending at
midnight GMT).

• Valid Cells Ingress

• Cells Ingress discarded due to HEC Errors

• Cells Egress

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Clocking Status

The following timing reference source status is available:

Statistics

• Reference Source—Current timing reference source.

• BITS A Status—Status of the BITS A timing source.

• BITS B Status—Status of the BITS B timing source.

• OC3 1 Status—Status of the first SONET port as a timing source.

• OC3 2 Status—Status of the second network SONET port as a timing source.

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Statistics

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Cisco MGX 8240 Hardware User’s Guide

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