Configuring IP SLAs ICMP Path Jitter Operations

This document describes how to configure an 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 commands.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table.

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

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

  • IP SLAs - ICMP Path Jitter 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, we recommend that you use the IP SLAs UDP Jitter operation.

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

  • A 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 commands and statistics can only be returned using the show ip sla commands.

  • IP SLAs - Path Jitter 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

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

An ICMP Path Jitter operation can be used a supplement to the standard UDP Jitter operation. For example, results from a UDP Jitter operation may indicate unexpected delays or high jitter values; an 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 IP SLAs - ICMP Path Jitter are approximates because ICMP only provides round trip times.

ICMP Path Jitter operations function 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


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.

Before you begin

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:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

ip sla responder

Example:

Example:


Device(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:


Device(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 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:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

ip sla operation-number

Example:

Device(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:

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

Enters IP SLA Path Jitter configuration mode for configuring an ICMP Path Jitter operation.

Step 5

frequency seconds

Example:

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

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

Step 6

end

Example:

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

Exits to privileged EXEC mode.

Example

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. 


Device(config)# ip sla 1
Device(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. end

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

ip sla operation-number

Example:

Device(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:

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

Enters IP SLA Path Jitter configuration mode for defing an ICMP Path Jitter operation.

Step 5

frequency seconds

Example:

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

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

Step 6

owner owner-id

Example:

Device(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:

Device(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:

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

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

Step 9

timeout milliseconds

Example:

Device(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:

Device(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:

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

Exits to privileged EXEC mode.

Scheduling IP SLAs Operations

Before you begin

  • All IP Service Level Agreements (SLAs) operations to be scheduled must be already configured.
  • The frequency of all operations scheduled in a multioperation group must be the same.
  • The list of one or more operation ID numbers to be added to a multioperation group must be limited to a maximum of 125 characters in length, including commas (,).

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. Enter one of the following commands:
    • 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 ]
    • ip sla group schedule group-operation-number operation-id-numbers {schedule-period schedule-period-range | schedule-together } [ageout seconds ] frequency group-operation-frequency [life {forever | seconds }] [start-time {hh: mm [: ss ] [month day | day month ] | pending | now | after hh: mm [: ss] }]
  4. end
  5. show ip sla group schedule
  6. show ip sla configuration

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

Enter one of the following commands:

  • 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 ]
  • ip sla group schedule group-operation-number operation-id-numbers {schedule-period schedule-period-range | schedule-together } [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:


Device(config)# ip sla schedule 10 life forever start-time now

Device(config)# ip sla group schedule 10 schedule-period frequency

Device(config)# ip sla group schedule 1 3,4,6-9 life forever start-time now 

Device(config)# ip sla schedule 1 3,4,6-9 schedule-period 50 frequency range 80-100

  • Configures the scheduling parameters for an individual IP SLAs operation.

  • Specifies an IP SLAs operation group number and the range of operation numbers for a multioperation scheduler.

Step 4

end

Example:


Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Step 5

show ip sla group schedule

Example:


Device# show ip sla group schedule

(Optional) Displays IP SLAs group schedule details.

Step 6

show ip sla configuration

Example:


Device# show ip sla configuration

(Optional) Displays IP SLAs configuration details.

Troubleshooting Tips

  • If the IP Service Level Agreements (SLAs) operation is not running and not generating statistics, add the verify-data command to the configuration (while configuring in IP SLA configuration mode) to enable data verification. When data verification is 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 trace and debug ip sla error commands to help troubleshoot issues with an IP SLAs operation.

What to Do Next

To add proactive threshold conditions and reactive triggering for generating traps (or for starting another operation) to an IP Service Level Agreements (SLAs) operation, see the “Configuring Proactive Threshold Monitoring” section.

Configuration Examples for IP SLAs ICMP Path Jitter Operations

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. 


Device# configure terminal
Device(config)# ip sla 15011
Device(config-sla-monitor)# path-jitter 10.222.1.100 source-ip 10.222.3.100 num-packets 20
Device(config-sla-monitor-pathJitter)# frequency 30
Device(config-sla-monitor-pathJitter)# exit
Device(config)# ip sla schedule 15011 life forever start-time now
Device(config)# exit
Device# 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

Standards and RFCs

Standard/RFC

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.

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

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

The following table provides release information about the feature or features described in this module. This table 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.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for IP SLAs ICMP Path Jitter Operations

Feature Name

Releases

Feature Information

IP SLAs Path Jitter Operation

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).

IPSLA 4.0 - IP v6 phase2

Support was added for operability in IPv6 networks.

The following commands are introduced or modified: path- jitter , show ip sla configuration , show ip sla summary .