Configuring Cisco IOS IP SLAs ICMP Path Jitter Operations

First Published: August 14, 2006
Last Updated: January 6, 2010

This document describes how to configure a Cisco IOS IP Service Level Agreements (SLAs) Internet Control Message Protocol (ICMP) Path Jitter operation to monitor hop-by-hop jitter (inter-packet delay variance). This document also demonstrates how the data gathered using the Path Jitter operations can be displayed and analyzed using Cisco IOS commands.

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 IP SLAs ICMP Path Jitter Operations" section.

Use Cisco Feature Navigator to find information about platform support and Cisco 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

•Prerequisites for ICMP Path Jitter Operations

•Restrictions for ICMP Path Jitter Operations

•Information About IP SLAs ICMP Path Jitter Operations

•How to Configure the IP SLAs ICMP Path Jitter Operation

•Configuration Examples for IP SLAs ICMP Path Jitter Operations

•Additional References

•Feature Information for IP SLAs ICMP Path Jitter Operations

Prerequisites for ICMP Path Jitter Operations

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

•In contrast with other IP SLAs operations, the IP SLAs Responder does not have to be enabled on either the target device or intermediate devices for Path Jitter operations. However, the operational efficiency may improve if you enable the IP SLAs Responder.

Restrictions for ICMP Path Jitter Operations

•The IP SLAs ICMP Path Jitter operation is ICMP-based. ICMP-based operations can compensate for source processing delay but cannot compensate for target processing delay. For more robust monitoring and verifying, use of the IP SLAs UDP Jitter operation is recommended.

•The jitter values obtained using the ICMP Path Jitter operation are approximates because ICMP does not provide the capability to embed processing times on routers in the packet. If the target router does not place ICMP packets as the highest priority, then the router will not respond properly. ICMP performance also can be affected by the configuration of priority queueing on the router and by ping response.

•The path jitter operation does not support hourly statistics and hop information.

•Unlike other IP SLAs operations, the ICMP Path Jitter operation is not supported in the RTTMON MIB. Path Jitter operations can only be configured using Cisco IOS commands and statistics can only be returned using the show ip sla commands.

•The IP SLAs Path Jitter operation does not support the IP SLAs History feature (statistics history buckets) because of the large data volume involved with Jitter operations.

•The following commands, available in Path Jitter configuration mode, do not apply to Path Jitter operations:

–history buckets-kept

–history distributions-of-statistics-kept

–history enhanced

–history filter

–history hours-of-statistics-kept

–history lives-kept

–history statistics-distribution-interval

–samples-of-history-kept

–lsr-path

–tos

–threshold

–verify-data

Information About IP SLAs ICMP Path Jitter Operations

•ICMP Path Jitter Operation

ICMP Path Jitter Operation

The IP SLAs ICMP Path Jitter operation provides hop-by-hop jitter, packet loss, and delay measurement statistics in an IP network. The Path Jitter operation functions differently than the standard UDP Jitter operation, which provides total one-way data and total round-trip data.

The ICMP Path Jitter operation can be used a supplement to the standard UDP Jitter operation. For example, results from the UDP Jitter operation may indicate unexpected delays or high jitter values; the ICMP Path Jitter operation could then be used to troubleshoot the network path and determine if traffic is bottlenecking in a particular segment along the transmission path.

The operation first discovers the hop-by-hop IP route from the source to the destination using a traceroute utility, and then uses ICMP echoes to determine the response times, packet loss and approximate jitter values for each hop along the path. The jitter values obtained using the ICMP Path Jitter operation are approximates because ICMP only provides round trip times.

The ICMP Path Jitter operation functions by tracing the IP path from a source device to a specified destination device, then sending N number of Echo probes to each hop along the traced path, with a time interval of T milliseconds between each Echo probe. The operation as a whole is repeated at a frequency of once every F seconds. The attributes are user-configurable, as shown here:

Path Jitter Operation Parameter
Default
Configured Using:

Number of echo probes (N)

10 echos

path-jitter command, num-packets option

Time between Echo probes, in milliseconds (T)

20 ms

path-jitter command, interval option

Note The operation's frequency is different than the operation's interval.

The frequency of how often the operation is repeated (F)

once every 60 seconds

frequency command


How to Configure the IP SLAs ICMP Path Jitter Operation

•Configuring the IP SLAs Responder on a Destination Device (optional)

•Configuring an ICMP Path Jitter Operation on the Source Device (required)

•Scheduling IP SLAs Operations (required)

Configuring the IP SLAs Responder on a Destination Device

Note An IP SLAs Responder is not required on either the target device or intermediate devices for Path Jitter operations. However, operational efficiency may improve if you enable the IP SLAs Responder.

Prerequisites

The networking device to be used as the responder must be a Cisco device and you must have connectivity to that device through the network.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip sla 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

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ip sla responder


Example:

Router(config)# ip sla responder

(Optional) Temporarily enables IP SLAs Responder functionality on a Cisco device in response to control messages from source.

•Control is enabled by default.

Step 4 

exit

Example:

Router(config)# exit

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

Configuring an ICMP Path Jitter Operation on the Source Device

Perform only one of the following procedures in this section:

•Configuring the IP SLAs Responder on a Destination Device

•Configuring an ICMP Path Jitter Operation with Additional Parameters

Configuring a Basic ICMP Path Jitter Operation

SUMMARY STEPS

1. enable

2. configure terminal

3. ip sla operation-number

4. path-jitter {destination-ip-address | destination-hostname} [source-ip {ip-address | hostname}] [num-packets packet-number] [interval milliseconds] [targetOnly]

5. frequency seconds

6. end

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 operation-number

Example:

Router(config)# ip sla 10

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

Step 4 

path-jitter {destination-ip-address | destination-hostname} [source-ip {ip-address | hostname}] [num-packets packet-number] [interval milliseconds] [targetOnly]

Example:

Router(config-ip-sla)# path-jitter 172.31.1.129 source-ip 10.2.30.1 num-packets 12 interval 22

Defines an ICMP Path Jitter operation and enters IP SLA Path Jitter configuration mode.

Step 5 

frequency seconds

Example:

Router(config-ip-sla-pathJitter)# frequency 30

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

Step 6 

end

Example:

Router(config-ip-sla-pathJitter)# end

Exits to privileged EXEC mode.

Examples

In the following example, the targetOnly keyword is used to bypass the hop-by-hop measurements. With this version of the command, echo probes will be sent to the destination only. 

Router(config)# ip sla 1

Router(config-ip-sla)# path-jitter 172.17.246.20 num-packets 50 interval 30 targetOnly

Configuring an ICMP Path Jitter Operation with Additional Parameters

SUMMARY STEPS

1. enable

2. configure terminal

3. ip sla operation-number

4. path-jitter {destination-ip-address | destination-hostname} [source-ip {ip-address | hostname}] [num-packets packet-number] [interval milliseconds] [targetOnly]

5. frequency seconds

6. owner owner-id

7. request-data-size bytes

8. tag text

9. timeout milliseconds

10. vrf vrf-name

11. 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

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ip sla operation-number

Example:

Router(config)# ip sla 10

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

Step 4 

path-jitter {destination-ip-address | destination-hostname} [source-ip {ip-address | hostname}] [num-packets packet-number] [interval milliseconds] [targetOnly]

Example:

Router(config-ip-sla)# path-jitter 172.31.1.129 source-ip 10.2.30.1 num-packets 12 interval 22

Defines an ICMP Path Jitter operation and enters IP SLA Path Jitter configuration mode.

Step 5 

frequency seconds

Example:

Router(config-ip-sla-pathJitter)# frequency 30

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

Step 6 

owner owner-id

Example:

Router(config-ip-sla-pathJitter)# owner admin

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

Step 7 

request-data-size bytes

Example:

Router(config-ip-sla-pathJitter)# request-data-size 64

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

Step 8 

tag text

Example:

Router(config-ip-sla-pathJitter)# tag TelnetPollServer1

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

Step 9 

timeout milliseconds

Example:

Router(config-ip-sla-pathJitter)# timeout 10000

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

Step 10 

vrf vrf-name

Example:

Router(config-ip-sla-pathJitter)# vrf vpn-A

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

Step 11 

end

Example:

Router(config-ip-sla-pathJitter)# end

Exits to privileged EXEC mode.

Scheduling IP SLAs Operations

Restrictions

•The frequency of all operations scheduled in a multioperation group must be the same.

•Operation ID numbers are limited to a maximum of 125 characters. Do not give large integer values as operation ID numbers.

SUMMARY STEPS

1. enable

2. configure terminal

For individual IP SLAs operations only:

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

For multioperation scheduler only:

4. ip sla group schedule group-operation-number operation-id-numbers schedule-period schedule-period-range [ageout seconds] [frequency group-operation-frequency] [life {forever | seconds}] [start-time {hh:mm[:ss] [month day | day month] | pending | now | after hh:mm:ss}]

5. exit

6. show ip sla group schedule

7. show ip sla configuration

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 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 schedule 10 start-time now life forever

For individual IP SLAs operations only:

Configures the scheduling parameters for an individual IP SLAs operation.

Step 4  

ip sla group schedule group-operation-number 
operation-id-numbers 
schedule-period schedule-period-range [ageout  
seconds] [frequency group-operation-frequency] 
[life {forever | seconds}] 
[start-time {hh:mm[:ss] 
[month day | day month] | pending | now | 
after hh:mm:ss}]
Example:

Router(config)# ip sla group schedule 1 3,4,6-9

For multioperation scheduler only:

Specifies an IP SLAs operation group number and the range of operation numbers to be scheduled in global configuration mode.

•The operation ID numbers are limited to a maximum of 125 characters. Do not use large integer values as operation ID numbers.

Step 5 

exit

Example:

Router(config)# exit

Exits to privileged EXEC mode.

Step 6 

show ip sla group schedule

Example: 
Router# show ip sla group schedule

(Optional) Displays the IP SLAs group schedule details.

Step 7  

show ip sla configuration
Example: 
Router# show ip sla configuration

(Optional) Displays the IP SLAs configuration details.

Examples

In the following example, a Path Jitter operation is configured to run over a VPN using the VRF "red" to the CE at 10.3.30.130: 

Router# configure terminal

Enter configuration commands, one per line.  End with the end command.

Router(config)# ip sla 7

Router(config-ip-sla)# path-jitter 10.3.30.130

Router(config-ip-sla-pathJitter)# vrf red

Router(config-ip-sla-pathJitter)# exit

Router(config)# ip sla schedule 7 start-time now life forever

 

Troubleshooting Tips

Use the debug ip sla trace and debug ip sla 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 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 Examples for IP SLAs ICMP Path Jitter Operations

•Example: Configuring a Path Jitter Operation

Example: Configuring a Path Jitter Operation

The following example shows the output when the ICMP Path Jitter operation is configured. Because the path jitter operation does not support hourly statistics and hop information, the output for the show ip sla statistics command for the path jitter operation displays only the statistics for the first hop.

The following example shows the output when the ICMP Path Jitter operation is configured. 

Router# configure terminal

Router(config)# ip sla 15011

Router(config-sla-monitor)# path-jitter 10.222.1.100 source-ip 10.222.3.100 num-packets 20

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

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

Router(config)# ip sla schedule 15011 life forever start-time now

Router(config)# exit

Router# show ip sla statistics 15011


Round Trip Time (RTT) for       Index 15011

        Latest RTT: 1 milliseconds

Latest operation start time: 15:37:35.443 EDT Mon Jun 16 2008

Latest operation return code: OK


---- Path Jitter Statistics ---- 


Hop IP 10.222.3.252:

Round Trip Time milliseconds:

        Latest RTT: 1 ms

        Number of RTT: 20

        RTT Min/Avg/Max: 1/1/3 ms

Jitter time milliseconds:

        Number of jitter: 2

        Jitter Min/Avg/Max: 2/2/2 ms

Packet Values:

        Packet Loss (Timeouts): 0

        Out of Sequence: 0

        Discarded Samples: 0

Operation time to live: Forever

Additional References

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

Cisco IOS IP SLAs commands

Cisco IOS IP SLAs Command Reference

Cisco IOS IP SLAs: general information

"Cisco IOS IP SLAs Overview" chapter of the Cisco IP SLAs Configuration Guide.


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

MIB support for the Path Jitter operation is not provided.

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

RFC 18891

RTP: A Transport Protocol for Real-Time Applications; see the section "Estimating the Interarrival Jitter"

1 Support for the listed RFC is not claimed; listed as a reference only.


Technical Assistance

Description
Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html


Feature Information for IP SLAs ICMP Path Jitter Operations

Table 1 lists the features in this module and provides links to specific configuration information.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which 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 1 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Table 1 Feature Information for IP SLAs ICMP Path Jitter Operations 

Feature Name
Releases
Feature Information

IP SLAs Path Jitter Operation

12.2(31)SB2
12.2(33)SRB1
12.2(33)SXH
12.3(14)T
15.0(1)S
Cisco IOS XE 3.1.0SG

The Cisco IOS IP SLAs Internet Control Message Protocol (ICMP) path jitter operation allows you to measure hop-by-hop jitter (inter-packet delay variance).


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Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.

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