Cisco IOS IP SLAs Configuration Guide, Release 12.4
IP SLAs--Analyzing IP Service Levels Using the UDP Jitter Operation
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IP SLAs—Analyzing IP Service Levels Using the UDP Jitter Operation

Table Of Contents

IP SLAs—Analyzing IP Service Levels Using the UDP Jitter Operation

Finding Feature Information

Contents

Information About the IP SLAs UDP Jitter Operation

IP SLAs UDP Jitter Operation

How to Configure the IP SLAs UDP Jitter Operation

Configuring the IP SLAs Responder on the Destination Device

Configuring and Scheduling a UDP Jitter Operation on the Source Device

Prerequisites

Restrictions

Configuring and Scheduling a Basic UDP Jitter Operation on the Source Device

Configuring and Scheduling a UDP Jitter Operation with Additional Characteristics

Configuration Example for the IP SLAs UDP Jitter Operation

Configuring a UDP Jitter Operation: Example

Where to Go Next

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for the IP SLAs UDP Jitter Operation


IP SLAs—Analyzing IP Service Levels Using the UDP Jitter Operation


First Published: May 2, 2005
Last Updated: March 10, 2009

This document describes how to use the Cisco IOS IP Service Level Agreements (SLAs) UDP jitter operation to analyze round-trip delay, one-way delay, one-way jitter, one-way packet loss, and connectivity in networks that carry UDP traffic.

Cisco IOS IP SLAs is an embedded feature set in Cisco IOS software that allows you to analyze IP service levels for IP applications and services, to increase productivity, to lower operational costs, and to reduce occurrences of network congestion or outages. IP SLAs uses active traffic monitoring—the generation of traffic in a continuous, reliable, and predictable manner—for measuring network performance. The accuracy of measured data is enhanced by enabling the IP SLAs Responder, available in Cisco routers, on the destination device. This module also demonstrates how the data gathered using the UDP jitter operation can be displayed and analyzed using the Cisco IOS command-line interface (CLI).


Note A VoIP-specific implementation of the UDP jitter operation is available to measure performance by simulating specific voice codecs and returned voice quality scores. For more information, see the "IP SLAs—Analyzing Service Levels Using the VoIP UDP Jitter Operation" chapter of the Cisco IOS IP SLAs Configuration Guide, Release 12.4.


Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for the IP SLAs UDP Jitter Operation" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

Information About the IP SLAs UDP Jitter Operation

How to Configure the IP SLAs UDP Jitter Operation

Configuration Example for the IP SLAs UDP Jitter Operation

Where to Go Next

Additional References

Feature Information for the IP SLAs UDP Jitter Operation

Information About the IP SLAs UDP Jitter Operation

To perform the tasks required to verify service levels using the IP SLAs UDP jitter operation, you should understand the following concept:

IP SLAs UDP Jitter Operation

IP SLAs UDP Jitter Operation

The IP SLAs UDP jitter operation was primarily designed to diagnose network suitability for real-time traffic applications such as voice over IP (VoIP), video over IP, or real-time conferencing.

Jitter means inter-packet delay variance. When multiple packets are sent consecutively from source to destination, for example, 10 ms apart, and if the network is behaving ideally, the destination should be receiving them 10 ms apart. But if there are delays in the network (like queuing, arriving through alternate routes, and so on) the arrival delay between packets might be greater than or less than 10 ms. Using this example, a positive jitter value indicates that the packets arrived greater than 10 ms apart. If the packets arrive 12 ms apart, then positive jitter is 2 ms; if the packets arrive 8 ms apart, then negative jitter is 2 ms. For delay-sensitive networks like VoIP, positive jitter values are undesirable, and a jitter value of 0 is ideal.

However, the IP SLAs UDP jitter operation does more than just monitor jitter. As the UDP jitter operation includes the data returned by the IP SLAs UDP operation, the UDP jitter operation can be used as a multipurpose data gathering operation. The packets IP SLAs generates carry packet sending sequence and receiving sequence information, and sending and receiving time stamps from the source and the operational target. Based on these, UDP jitter operations are capable of measuring the following:

Per-direction jitter (source to destination and destination to source)

Per-direction packet-loss

Per-direction delay (one-way delay)

Round-trip delay (average round-trip time)

As the paths for the sending and receiving of data may be different (asymmetric), the per-direction data allow you to more readily identify where congestion or other problems are occurring in the network.

The UDP jitter operation functions by generating synthetic (simulated) UDP traffic. The UDP jitter operation sends N UDP packets, each of size S, sent T milliseconds apart, from a source router to a target router, at a given frequency of F. By default, ten packet-frames (N), each with a payload size of 10 bytes (S) are generated every 10 ms (T), and the operation is repeated every 60 seconds (F). Each of these parameters are user-configurable, so as to best simulate the IP service you are providing, or want to provide.

How to Configure the IP SLAs UDP Jitter Operation

This section contains the following procedures:

Configuring the IP SLAs Responder on the Destination Device (required)

Configuring and Scheduling a UDP Jitter Operation on the Source Device

Configuring the IP SLAs Responder on the Destination Device

Before configuring a UDP jitter operation on the source device, the IP SLAs Responder must be enabled on the target device (the operational target). The IP SLAs Responder is available only on Cisco IOS software-based devices.

Perform this task to enable the IP SLAs Responder.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip sla monitor responder

4. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal


Router# configure terminal

Enters global configuration mode.

Step 3 

ip sla monitor responder


Router(config)# ip sla monitor responder

Enables the IP SLAs Responder.

Step 4 

exit


Router(config)# exit

(Optional) Exits global configuration mode and returns to privileged EXEC mode.

Configuring and Scheduling a UDP Jitter Operation on the Source Device

The IP SLAs operations function by generating synthetic (simulated) network traffic. A single IP SLAs operation (for example, IP SLAs operation 10) will repeat at a given frequency for the lifetime of the operation.

A single UDP jitter operation consists of N UDP packets, each of size S, sent T milliseconds apart, from a source router to a target router, at a given frequency of F. By default, ten packets (N), each with an RTP payload size of 32 bytes (S), are generated every 20 ms (T), and the operation is repeated every 60 seconds (F). Each of these parameters are user-configurable, as shown in Table 1.

Table 1 UDP Jitter Operation Parameters 

UDP Jitter Operation Parameter
Default
Configured Using:

Number of packets (N)

10 packets

type jitter dest-ipaddr command, num-packets option

Payload size per packet (S)

32 bytes

request-data-size command

Time between packets, in milliseconds (T)

20 ms

type jitter dest-ipaddr command, interval option

Elapsed time before the operation repeats, in seconds (F)

60 seconds

frequency (IP SLA) command


Prerequisites

Use of the UDP jitter operation requires that the IP SLAs Responder be enabled on the target Cisco device. To enable the Responder, perform the task in the "Configuring the IP SLAs Responder on the Destination Device" section.

Time synchronization, such as that provided by NTP, is required between the source and the target device in order to provide accurate one-way delay (latency) measurements. To configure NTP on the source and target devices, perform the tasks in the "Performing Basic System Management" chapter of the Cisco IOS Configuration Fundamentals Configuration Guide, Release 12.2. Time synchronization is not required for the one-way jitter and packet loss measurements, however. If the time is not synchronized between the source and target devices, one-way jitter and packet loss data will be returned, but values of "0" will be returned for the one-way delay measurements provided by the UDP jitter operation.

Before configuring any IP SLAs application, you can use the show ip sla monitor application command to verify that the operation type is supported on your software image.

Restrictions

The responder should not configure a permanent port for the same sender. If the responder configures the permanent port for the same sender, even if the packets are successfully sent (no timeout or packet loss issues), the jitter values will be zero.

Configuring and Scheduling a Basic UDP Jitter Operation on the Source Device

Perform this task to configure and schedule a basic UDP jitter operation.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip sla monitor operation-number

4. type jitter dest-ipaddr {hostname | ip-address} dest-port port-number [num-packets number-of-packets] [interval inter-packet-interval]

5. frequency seconds

6. exit

7. ip sla monitor schedule operation-number [life {forever | seconds}] [start-time {hh:mm[:ss] [month day | day month] | pending | now | after hh:mm:ss] [ageout seconds] [recurring]

8. exit

9. show ip sla monitor configuration [operation-number]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ip sla monitor operation-number

Example:

Router(config)# ip sla monitor 10

Begins configuration for an IP SLAs operation and enters IP SLA monitor configuration mode.

Step 4 

type jitter dest-ipaddr {hostname | ip-address} dest-port port-number
[source-ipaddr {name | ip-address}] [source-port port-number]
[num-packets number-of-packets]
[interval inter-packet-interval]
[control {enable | disable}]

Example:

Router(config-sla-monitor)# type jitter dest-ipaddr 172.29.139.134 dest-port 5000

Configures the IP SLAs operation as a UDP jitter operation and enters UDP jitter configuration submode.

Use the dest-ipaddr keyword to specify the IP address or IP hostname of the destination for the UDP jitter operation.

Use the dest-port keyword and associated option to specify the destination port number, in the range from 1 to 65535.

All other keywords and arguments are optional. See the command reference document for more information. The default number of packets (num-packets) sent is 10. The default interval between packets is 20 milliseconds.

The control disable keyword combination should only be used if you are disabling the IP SLAs control protocol on both the source and target routers. The IP SLAs control protocol is enabled by default.

After entering this command, the command-line interface (CLI) enters IP SLA monitor jitter configuration mode to allow you to specify optional characteristics for the operation.

Step 5 

frequency seconds

Example:

Router(config-sla-monitor-jitter)# frequency 30

(Optional) Sets the rate at which a specified IP SLAs operation repeats.

Step 6 

exit

Example:

Router(config-sla-monitor-jitter)# exit

Exits UDP jitter configuration submode and returns to global configuration mode.

Step 7 

ip sla monitor schedule operation-number [life {forever | seconds}] [start-time {hh:mm[:ss] [month day | day month] | pending | now | after hh:mm:ss] [ageout seconds] [recurring]

Example:

Router(config)# ip sla monitor schedule 5 start-time now life forever

Configures the scheduling parameters for an individual IP SLAs operation.

Step 8 

exit

Example:

Router(config)# exit

(Optional) Exits global configuration mode and returns to privileged EXEC mode.

Step 9 

show ip sla monitor configuration [operation-number]

Example:

Router# show ip sla monitor configuration 10

(Optional) Displays configuration values including all defaults for all IP SLAs operations or a specified operation.

Troubleshooting Tips

If the IP SLAs operation is not running and generating statistics, add the verify-data command to the configuration of the operation (while configuring in IP SLA monitor mode) to enable data verification. When enabled, each operation response is checked for corruption. Use the verify-data command with caution during normal operations because it generates unnecessary overhead.

Use the debug ip sla monitor trace and debug ip sla monitor error commands to help troubleshoot issues with an IP SLAs operation.

What to Do Next

To view and interpret the results of an IP SLAs operation use the show ip sla monitor statistics command. Checking the output for fields that correspond to criteria in your service level agreement will help you determine whether the service metrics are acceptable.

If you with configure and schedule a UDP jitter operation with additional characteristics, perform the task in the "Configuring and Scheduling a UDP Jitter Operation with Additional Characteristics" section.

Configuring and Scheduling a UDP Jitter Operation with Additional Characteristics

Perform this task to configure and schedule a UDP jitter operation with additional parameters.

Restrictions

The IP SLAs UDP jitter operation does not support the IP SLAs History feature (statistics history buckets) because of the large data volume involved with UDP jitter operations. This means that the following commands are not supported for UDP jitter operations: buckets-of-history-kept, filter-for-history, lives-of-history-kept, samples-of-history-kept, and show ip sla monitor history.

The MIB used by IP SLAs (CISCO-RTTMON-MIB) limits the hours-of-statistics kept for the UDP jitter operation to two hours. Configuring a larger value using the hours-of-statistics hours global configuration change will not increase the value beyond two hours.

However, the Data Collection MIB can be used to collect historical data for the operation. See the CISCO-DATA-COLLECTION-MIB (available from http://www.cisco.com/go/mibs).

SUMMARY STEPS

1. enable

2. configure terminal

3. ip sla monitor operation-number

4. type jitter dest-ipaddr {hostname | ip-address} dest-port port-number [source-ipaddr {name | ip-address}] [source-port port-number] [num-packets number-of-packets] [interval inter-packet-interval] [control {enable | disable}]

5. dest-ipaddr ip-address

6. dest-port port-number

7. distributions-of-statistics-kept size

8. enhanced-history [interval seconds] [buckets number-of-buckets]

9. frequency seconds

10. hours-of-statistics-kept hours

11. owner owner-id

12. request-data-size bytes

13. statistics-distribution-interval milliseconds

14. tag text

15. threshold milliseconds

16. timeout milliseconds

17. tos number

18. verify-data

19. vrf vrf-name

20. exit

21. ip sla monitor schedule operation-number [life {forever | seconds}] [start-time {hh:mm[:ss] [month day | day month] | pending | now | after hh:mm:ss] [ageout seconds] [recurring]

22. exit

23. show ip sla monitor configuration [operation-number]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ip sla monitor operation-number

Example:

Router(config)# ip sla monitor 10

Begins configuration for an IP SLAs operation and enters IP SLA monitor configuration mode.

Step 4 

type jitter dest-ipaddr {hostname | ip-address} dest-port port-number
[source-ipaddr {name | ip-address}] [source-port port-number]
[num-packets number-of-packets]
[interval inter-packet-interval]
[control {enable | disable}]

Example:

Router(config-sla-monitor)# type jitter dest-ipaddr 172.29.139.134 dest-port 5000

Configures the IP SLAs operation as a UDP jitter operation and enters UDP jitter configuration submode.

Use the dest-ipaddr keyword to specify the IP address or IP hostname of the destination for the UDP jitter operation.

Use the dest-port keyword and associated option to specify the destination port number, in the range from 1 to 65535.

All other keywords and arguments are optional. See the command reference document for more information. The default number of packets (num-packets) sent is 10. The default interval between packets is 20 milliseconds.

The control disable keyword combination should only be used if you are disabling the IP SLAs control protocol on both the source and target routers. The IP SLAs control protocol is enabled by default.

After entering this command, the command-line interface (CLI) enters IP SLA monitor jitter configuration mode to allow you to specify optional characteristics for the operation.

Step 5 

dest-ipaddr ip-address

Example:

Router(config-sla-monitor-jitter)# dest-ipaddr 172.29.139.135

(Optional) Specifies the destination IP address for the IP SLAs operation.

Use of this command will overwrite the IP address specified in the syntax of the type jitter command.

This command allows you to change the target device for the operation without disabling and reenabling the operation type.

Step 6 

dest-port port-number

Example:

Router(config-sla-monitor-jitter)# dest-port 5001

(Optional) Specifies the destination port number for the IP SLAs operation.

Use of this command will overwrite the port number specified in the syntax of the type jitter command.

This command allows you to change the target port for the operation without disabling and reenabling the operation type.

Step 7 

distributions-of-statistics-kept size

Example:

Router(config-sla-monitor-jitter)# distributions-of-statistics-kept 5

(Optional) Sets the number of statistics distributions kept per hop during an IP SLAs operation.

Step 8 

enhanced-history [interval seconds] [buckets number-of-buckets]

Example:

Router(config-sla-monitor-jitter)# enhanced-history interval 900 buckets 100

(Optional) Enables enhanced history gathering for an IP SLAs operation.

Step 9 

frequency seconds

Example:

Router(config-sla-monitor-jitter)# frequency 30

(Optional) Sets the rate at which a specified IP SLAs operation repeats.

Step 10 

hours-of-statistics-kept hours

Example:

Router(config-sla-monitor-jitter)# hours-of-statistics-kept 4

(Optional) Sets the number of hours for which statistics are maintained for an IP SLAs operation.

Step 11 

owner owner-id

Example:

Router(config-sla-monitor-jitter)# owner admin

(Optional) Configures the Simple Network Management Protocol (SNMP) owner of an IP SLAs operation.

Step 12 

request-data-size bytes

Example:

Router(config-sla-monitor-jitter)# request-data-size 64

(Optional) Sets the protocol data size in the payload of an IP SLAs operation's request packet.

Step 13 

statistics-distribution-interval milliseconds

Example:
Router(config-sla-monitor-jitter)# 
statistics-distribution-interval 10

(Optional) Sets the time interval for each statistics distribution kept for an IP SLAs operation.

Step 14 

tag text

Example:

Router(config-sla-monitor-jitter)# tag TelnetPollServer1

(Optional) Creates a user-specified identifier for an IP SLAs operation.

Step 15 

threshold milliseconds

Example:

Router(config-sla-monitor-jitter)# threshold 10000

(Optional) Sets the upper threshold value for calculating network monitoring statistics created by an IP SLAs operation.

Step 16 

timeout milliseconds

Example:

Router(config-sla-monitor-jitter)# timeout 10000

(Optional) Sets the amount of time an IP SLAs operation waits for a response from its request packet.

Step 17 

tos number

Example:

Router(config-sla-monitor-jitter)# tos 160

(Optional) Defines a type of service (ToS) byte in the IP header of an IP SLAs operation.

Step 18 

verify-data

Example:

Router(config-sla-monitor-jitter)# verify-data

(Optional) Causes an IP SLAs operation to check each reply packet for data corruption.

Step 19 

vrf vrf-name

Example:

Router(config-sla-monitor-jitter)# vrf vpn-A

(Optional) Allows monitoring within Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs) using IP SLAs operations.

Step 20 

exit

Example:

Router(config-sla-monitor-jitter)# exit

Exits UDP jitter configuration submode and returns to global configuration mode.

Step 21 

ip sla monitor schedule operation-number [life {forever | seconds}] [start-time {hh:mm[:ss] [month day | day month] | pending | now | after hh:mm:ss] [ageout seconds] [recurring]

Example:

Router(config)# ip sla monitor schedule 5 start-time now life forever

Configures the scheduling parameters for an individual IP SLAs operation.

Step 22 

exit

Example:

Router(config)# exit

(Optional) Exits global configuration mode and returns to privileged EXEC mode.

Step 23 

show ip sla monitor configuration [operation-number]

Example:

Router# show ip sla monitor configuration 10

(Optional) Displays configuration values including all defaults for all IP SLAs operations or a specified operation.

Troubleshooting Tips

If the IP SLAs operation is not running and generating statistics, add the verify-data command to the configuration of the operation (while configuring in IP SLA monitor mode) to enable data verification. When enabled, each operation response is checked for corruption. Use the verify-data command with caution during normal operations because it generates unnecessary overhead.

Use the debug ip sla monitor trace and debug ip sla monitor error commands to help troubleshoot issues with an IP SLAs operation.

What to Do Next

To view and interpret the results of an IP SLAs operation use the show ip sla monitor statistics command. Checking the output for fields that correspond to criteria in your service level agreement will help you determine whether the service metrics are acceptable.

Configuration Example for the IP SLAs UDP Jitter Operation

This section provides the following configuration example:

Configuring a UDP Jitter Operation: Example

Configuring a UDP Jitter Operation: Example

In the following example, two operations are configured as UDP jitter operations, with operation 2 starting five seconds after the first operation. Both operations will run indefinitely.

ip sla monitor 1
 type jitter dest-ipaddr 20.0.10.3 dest-port 65051 num-packets 20
 request-data-size 160
 tos 128
 frequency 30
ip sla monitor schedule 1 start-time after 00:05:00
ip sla monitor 2
 type jitter dest-ipaddr 20.0.10.3 dest-port 65052 num-packets 20 interval 10
 request-data-size 20
 tos 64
 frequency 30
ip sla monitor schedule 2 start-time after 00:05:05


On the target (destination) device:

ip sla monitor responder

Where to Go Next

If you want to configure multiple Cisco IOS IP SLAs operations at once, see the "IP SLAs—Multiple Operation Scheduling" chapter of the Cisco IOS IP SLAs Configuration Guide, Release 12.4.

If you want to configure threshold parameters for an IP SLAs operation, see the "IP SLAs—Proactive Threshold Monitoring" chapter of the Cisco IOS IP SLAs Configuration Guide, Release 12.4.

If you want to configure other types of IP SLAs operations, see the "Where to Go Next" section of the "Cisco IOS IP SLAs Overview" chapter of the Cisco IOS IP SLAs Configuration Guide, Release 12.4.

Additional References

The following sections provide references related to configuring IP SLAs UDP Jitter operations.

Related Documents

Related Topic
Document Title

Overview of Cisco IOS IP SLAs

"Cisco IOS IP SLAs Overview" chapter of the Cisco IOS IP SLAs Configuration Guide, Release 12.4

Cisco IOS IP SLAs commands: complete command syntax, defaults, command mode, command history, usage guidelines, and examples

Cisco IOS IP SLAs Command Reference, Release 12.4


Standards

Standards
Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by features in this document.


MIBs

MIBs
MIBs Link

CISCO-RTTMON-MIB

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFCs
Title

No specific RFCs are supported by the features in this document.


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for the IP SLAs UDP Jitter Operation

Table 2 lists the features in this module and provides links to specific configuration information. Only features that were introduced or modified in Cisco IOS Release 12.3(14)T or a later release appear in the table.

For information on a feature in this technology that is not documented here, see the "Cisco IOS IP SLAs Features Roadmap."

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.


Note Table 2 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.


Table 2 Feature Information for the IP SLAs UDP Jitter Operation 

Feature Name
Releases
Feature Information

IP SLAs UDP Jitter Operation

12.3(14)T

The Cisco IOS IP SLAs User Datagram Protocol (UDP) jitter operation allows you to measure round-trip delay, one-way delay, one-way jitter, one-way packet loss, and connectivity in networks that carry UDP traffic.