Cisco Nexus 7000 Series NX-OS IP SLAs Configuration Guide
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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.
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 nmessages 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.
Procedure
Command or Action
Purpose
Step 1
enable
Example:
switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configure terminal
Example:
switch# configure terminal
Enters global configuration mode.
Step 3
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]
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: