IP SLAs support proactive threshold monitoring and notifications for
performance parameters such as average jitter, unidirectional latency,
bidirectional round-trip time (RTT), and connectivity for most IP SLAs
operations. The proactive monitoring capability also provides options for
configuring reaction thresholds for important VoIP related parameters including
unidirectional jitter, unidirectional packet loss, and unidirectional VoIP
voice quality scoring.
Notifications for IP SLAs are configured as a triggered reaction.
Packet loss, jitter, and Mean Operation Score (MOS) statistics are specific to
IP SLAs jitter operations. Notifications can be generated for violations in
either direction (source-to-destination and destination-to-source) or for
out-of-range RTT values for packet loss and jitter. Events, such as traps, are
triggered when the RTT value rises above or falls below a specified threshold.
IP SLAs can generate system logging (syslog) messages when a reaction
condition occurs. System logging messages can be sent as Simple Network
Management Protocol (SNMP) traps (notifications) using the CISCO-RTTMON-MIB.
SNMP traps for IP SLAs are supported by the CISCO-RTTMON-MIB and
CISCO-SYSLOG-MIB.
Severity levels in the CISCO-SYSLOG-MIB are
SyslogSeverity INTEGER {emergency(1), alert(2), critical(3), error(4),
warning(5), notice(6), info(7), debug(8)}.
The values for severity levels are defined differently for the system
logging process in the Cisco NX-OS software. Severity levels for the system logging
process in the Cisco NX-OS software are: {emergency (0), alert
(1), critical (2), error (3), warning (4), notice (5), informational (6),
debugging (7)}.
IP SLAs threshold violations are logged as level 6 (informational)
within the Cisco NX-OS system logging process but are sent as level 7 (info)
traps from the CISCO-SYSLOG-MIB.
Notifications are not issued for every occurrence of a threshold
violation.
The following figure shows the sequence for a triggered reaction that occurs
when the monitored element exceeds the upper threshold. An event is sent and a
notification is issued when the rising threshold is exceeded for the first
time. Subsequent threshold-exceeded notifications are issued only after the
monitored value falls below the falling threshold before exceeding the rising
threshold again.
Figure 1. IP SLAs Triggered Reaction Condition and Notifications for
Threshold Exceeded
1
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An event is sent and a threshold-exceeded notification is
issued when the rising threshold is exceeded for the first time.
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2
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Consecutive over-rising threshold violations occur without
issuing additional notifications.
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3
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The monitored value goes below the falling threshold.
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4
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Another threshold-exceeded notification is issued when the
rising threshold is exceeded only after the monitored value first fell below
the falling threshold.
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Note |
A lower-threshold notification is also issued the first time that
the monitored element falls below the falling threshold (3). Subsequent notifications for lower-threshold violations are issued only
after the rising threshold is exceeded before the monitored value falls below
the falling threshold again.
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