Cisco Nexus 9000 Series NX-OS IP SLAs Configuration Guide, Release 9.3(x)
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Configuring Proactive Threshold Monitoring for IP SLAs Operations
This chapter describes the proactive monitoring capabilities of IP Service Level Agreements (SLAs) using thresholds and reaction
triggering.
This chapter includes the following sections:
Information About IP
SLAs Reaction Configuration
IP SLAs reactions are
configured to trigger when a monitored value exceeds or falls below a specified
level or when a monitored event, such as a timeout or connection loss, occurs.
If IP SLAs measure too high or too low of any configured reaction, IP SLAs can
generate a notification to a network management application or trigger another
IP SLA operation to gather more data.
IP SLAs Threshold
Monitoring and Notifications
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
An event is
sent and a threshold-exceeded notification is issued when the rising threshold
is exceeded for the first time.
2
Consecutive
over-rising threshold violations occur without issuing additional
notifications.
3
The
monitored value goes below the falling threshold.
4
Another
threshold-exceeded notification is issued when the rising threshold is exceeded
only after the monitored value first fell below the falling threshold.
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.
RTT Reactions for
Jitter Operations
RTT reactions for
jitter operations are triggered only at the end of the operation and use the
latest value for the return-trip time (LatestRTT), which matches the value of
the average return-trip time (RTTAvg).
SNMP traps for RTT
for jitter operations are based on the value of the average return-trip time
(RTTAvg) for the whole operation and do not include RTT values for each
individual packet sent during the operation. For example, if the average is
below the threshold, up to half of the packets can actually be above the
threshold, but this detail is not included in the notification because the
value is for the whole operation only.
Only syslog messages are supported for RTTAvg threshold violations. Syslog messages are sent from the CISCO-RTTMON-MIB.
Configuring
Proactive Threshold Monitoring
This section
describes how to configure thresholds and reactive triggering for generating
traps or starting another operation.
Before you begin
Configure IP SLAs operations to be started when violation conditions are met.
Note
RTT reactions for jitter operations are triggered only at the end of the operation and use the latest value for the return-trip
time (LatestRTT).
SNMP traps for RTT for jitter operations are based on the average value for the return-trip time (RTTAvg) for the whole operation
only and do not include return-trip time values for individual packets sent during the operation. Only syslog messages are
supported for RTTAvg threshold violations.
Only syslog messages are supported for RTT violations during jitter operations.
Only SNMP traps are supported for RTT violations during nonjitter operations.
Only syslog messages are supported for non-RTT violations other than timeout, connectionLoss, or verifyError.
Both SNMP traps and syslog messages are supported for timeout, connectionLoss, or verifyError violations only.
SUMMARY STEPS
enable
configure
terminal
ip sla
reaction-configurationoperation-numberreactmonitored-element[action-typeoption] [threshold-type {average [number-of-measurements] |
consecutive
[occurrences] |
immediate |
never |
xofy [x-valuey-value]}] [threshold-valueupper-thresholdlower-threshold]
ip sla
reaction-triggeroperation-numbertarget-operation
Required if
the
snmp-server enable
traps command is configured.
Step 8
exit
Example:
switch(config)# exit
Exits global
configuration mode and returns to privileged EXEC mode.
Step 9
show ip
sla reaction configuration [operation-number]
Example:
switch# show ip sla reaction configuration 10
(Optional)
Displays the configuration of proactive threshold monitoring.
Step 10
show ip sla reaction
trigger [operation-number]
Example:
switch# show ip sla reaction trigger 2
(Optional)
Displays the configuration status and operational state of target operations to
be triggered.
Configuration
Example for an IP SLAs Reaction Configuration
This example shows
how to configure IP SLAs operation 10 to send an SNMP logging trap when the MOS
value either exceeds 4.9 (best quality) or falls below 2.5 (poor quality):
switch(config)# ip sla reaction-configuration 10 react mos threshold-type immediate threshold-value 490 250 action-type trapOnly
This example shows
how to display the default configuration:
switch# show ip sla reaction-configuration 1
Entry number: 1
Index: 1
Reaction: mos
Threshold Type: Immediate
Rising: 490
Falling: 250
Action Type: Trap only
switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# ip sla reaction-configuration 10 react mos threshold-type immediate threshold-value 490 250 action-type trapOnly
switch(config)# show ip sla reaction-configuration 1
Entry number: 1
Reaction: rtt
Threshold Type: Never
Rising (milliseconds): 5000
Falling (milliseconds): 3000
Threshold Count: 5
Threshold Count2: 5
Action Type: None
Verification Example
for an IP SLAs Reaction Configuration
This example shows
that multiple monitored elements are configured for the IP SLAs operation (1),
as indicated by the values of Reaction: in the output:
Configuration
Example for Triggering SNMP Notifications
This example shows
how to configure proactive threshold monitoring so that CISCO-SYSLOG-MIB traps
are sent to the remote host at 10.1.1.1 if the threshold values for RTT or VoIP
MOS are violated:
! Configure the operation on source.
switch(config)# ip sla 1
switch(config-ip-sla)# udp-jitter 10.1.1.1 3000 codec g711alaw
switch(config-ip-sla-jitter)# exit
switch(config)# ip sla schedule 1 start now life forever
! Configure thresholds and reactions.
switch(config)# ip sla reaction-configuration 1 react rtt threshold-type immediate threshold-value 3000 2000 action-type trapOnly
switch(config)# ip sla reaction-configuration 1 react MOS threshold-type consecutive 4 threshold-value 390 220 action-type trapOnly
switch(config)# ip sla logging traps
! The following command sends traps to the specified remote host.
switch(config)# snmp-server host 10.1.1.1 version 2c public
! The following command is needed for the system to generate CISCO-SYSLOG-MIB traps.
switch(config)# snmp-server enable traps
This example shows
that IP SLAs threshold violation notifications are generated as level 6
(informational) in the Cisco NX-OS system logging process:
3d18h:%RTT-6-SAATHRESHOLD:RTR(11):Threshold exceeded for MOS
This example shows
an SNMP notification from the CISCO-SYSLOG-MIB for the same violation is a
level 7 (info) notification: