Configuring Cisco IOS IP SLAs DHCP Operations

First Published: August 14, 2006
Last Updated: September 10, 2010

This module describes how to configure the Cisco IOS IP Service Level Agreements (SLAs) Dynamic Host Control Protocol (DHCP) operation to measure the response time between a Cisco device and a DHCP server to obtain an IP address.

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 Cisco IOS IP SLAs DHCP 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

•Information About Cisco IOS IP SLAs DHCP Operations

•How to Configure Cisco IOS IP SLAs DHCP Operations

•Configuration Examples for Cisco IOS IP SLAs DHCP Operations

•Additional References

•Feature Information for Cisco IOS IP SLAs DHCP Operations

Information About Cisco IOS IP SLAs DHCP Operations

•DHCP Operation

•IP SLAs DHCP Relay Agent Options

DHCP Operation

DHCP provides a mechanism for allocating IP addresses dynamically so that addresses can be reused when hosts no longer need them. The DHCP operation measures the round-trip time (RTT) taken to discover a DHCP server and obtain a leased IP address from it. IP SLAs releases the leased IP address after the operation.

You can use the RTT information to determine DHCP performance levels.

There are two modes for the DHCP operation. By default, the DHCP operation sends discovery packets on every available IP interface on the router. If a specific server is configured on the router, discovery packets are sent only to the specified DHCP server.

IP SLAs DHCP Relay Agent Options

A DHCP relay agent is any host that forwards DHCP packets between clients and servers. Relay agents are used to forward requests and replies between clients and servers when they are not on the same physical subnet. Relay agent forwarding is distinct from the normal forwarding of an IP router, where IP packets are switched between networks somewhat transparently. Relay agents receive DHCP messages and then generate a new DHCP message to send out on another interface.

The IP SLAs DHCP operation contains a relay agent information option—Option 82—which is inserted by the DHCP relay agent when forwarding client-originated DHCP packets to a DHCP server. Servers recognizing the relay agent information option may use the information to implement IP address or other parameter assignment policies. The DHCP server echoes the option back verbatim to the relay agent in server-to-client replies, and the relay agent strips the option before forwarding the reply to the client.

Option 82 includes three suboptions that convey information known by the relay agent:

•circuit-id—identifies the incoming circuit.

•remote-id—provides a trusted identifier for a remote high-speed modem.

•subnet-mask—identifies the mask of the logical IP subnet from which the relay agent received the client DHCP packet.

How to Configure Cisco IOS IP SLAs DHCP Operations

Note There is no need to configure an IP SLAs responder on the destination device.

•Configuring a DHCP Operation on the Source Device (required)

•Scheduling IP SLAs Operations (required)

Configuring a DHCP Operation on the Source Device

Perform one of the following tasks:

•Configuring a DHCP Operation on the Source Device

•Configuring a DHCP Operation with Optional Parameters

Configuring a Basic DHCP Operation

SUMMARY STEPS

1. enable

2. configure terminal

3. ip sla operation-number

4. dhcp {destination-ip-address | destination-hostname} [source-ip {ip-address | hostname}] [option-82 [circuit-id circuit-id] [remote-id remote-id] [subnet-mask subnet-mask]]

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 

dhcp {destination-ip-address | destination-hostname} [source-ip {ip-address | hostname}] [option-82 [circuit-id circuit-id] [remote-id remote-id] [subnet-mask subnet-mask]]

Example:

Router(config-ip-sla)# dhcp 10.10.10.3

Defines a DHCP operation and enters IP SLA DHCP configuration mode.

Step 5 

frequency seconds

Example:

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

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

Step 6 

end

Example:

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

Exits to privileged EXEC mode.

Configuring a DHCP Operation with Optional Parameters

SUMMARY STEPS

1. enable

2. configure terminal

3. ip sla operation-number

4. dhcp {destination-ip-address | destination-hostname} [source-ip {ip-address | hostname}] [option-82 [circuit-id circuit-id] [remote-id remote-id] [subnet-mask subnet-mask]]

5. history buckets-kept size

6. history distributions-of-statistics-kept size

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

8. history filter {none | all | overThreshold | failures}

9. frequency seconds

10. history hours-of-statistics-kept hours

11. history lives-kept lives

12. owner owner-id

13. history statistics-distribution-interval milliseconds

14. tag text

15. threshold milliseconds

16. timeout milliseconds

17. 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 

dhcp {destination-ip-address | destination-hostname} [source-ip {ip-address | hostname}] [option-82 [circuit-id circuit-id] [remote-id remote-id] [subnet-mask subnet-mask]]

Example:

Router(config-ip-sla)# dhcp 10.10.10.3 option-82 circuit-id 10005A6F1234

Defines a DHCP operation and enters IP SLA DHCP configuration mode.

Step 5 

history buckets-kept size

Example:

Router(config-ip-sla-dhcp)# history buckets-kept 25

(Optional) Sets the number of history buckets that are kept during the lifetime of an IP SLAs operation.

Step 6 

history distributions-of-statistics-kept size

Example:

Router(config-ip-sla-dhcp)# history distributions-of-statistics-kept 5

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

Step 7 

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

Example:

Router(config-ip-sla-dhcp)# history enhanced interval 900 buckets 100

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

Step 8 

history filter {none | all | overThreshold | failures}

Example:

Router(config-ip-sla-dhcp)# history filter failures

(Optional) Defines the type of information kept in the history table for an IP SLAs operation.

Step 9 

frequency seconds

Example:

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

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

Step 10 

history hours-of-statistics-kept hours

Example:

Router(config-ip-sla-dhcp)# history hours-of-statistics-kept 4

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

Step 11 

history lives-kept lives

Example:

Router(config-ip-sla-dhcp)# history lives-kept 5

(Optional) Sets the number of lives maintained in the history table for an IP SLAs operation.

Step 12 

owner owner-id

Example:

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

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

Step 13 

history statistics-distribution-interval milliseconds

Example:

Router(config-ip-sla-dhcp)# history 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-ip-sla-dhcp)# tag TelnetPollServer1

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

Step 15 

threshold milliseconds

Example:

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

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

Step 17 

end

Example:

Router(config-ip-sla-dhcp)# 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 multioperations 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 1 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 mulioperation scheduler only:

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

•The frequency of all operations scheduled in the operation group should be the same.

•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

The following sample output shows the configuration of all the IP SLAs parameters (including defaults) for the DHCP operation number 12. 

Router# show ip sla configuration 12


Complete Configuration Table (includes defaults)

Entry number: 12

Owner: DHCP-Test

Tag: DHCP-Test

Type of operation to perform: dhcp

Target address: 10.10.10.3

Source address: 0.0.0.0

Operation timeout (milliseconds): 5000

Dhcp option:

Operation frequency (seconds): 30

Next Scheduled Start Time: Start Time already passed

Group Scheduled: FALSE

Life (seconds): Forever

Entry Ageout (seconds): never

Recurring (Starting Everyday): FALSE

Status of entry (SNMP RowStatus): Active

Threshold (milliseconds): 5000

Number of statistic hours kept: 2

Number of statistic distribution buckets kept: 1

Statistic distribution interval (milliseconds): 20

Number of history Lives kept: 0

Number of history Buckets kept: 15

History Filter Type: None

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 add proactive threshold conditions and reactive triggering for generating traps, or for starting another operation, to an IP SLAs operation, see Configuring Proactive Threshold Monitoring.

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 Cisco IOS IP SLAs DHCP Operations

•Example: Configuration for an IP SLAs DHCP Operation

Example: Configuration for an IP SLAs DHCP Operation

In the following example, IP SLAs operation number 12 is configured as a DHCP operation enabled for DHCP server 172.16.20.3. Note that DHCP option 82 is used to specify the circuit ID.

Router B Configuration 

ip dhcp-server 172.16.20.3

!

ip sla 12

 dhcp 10.10.10.3 option-82 circuit-id 10005A6F1234

 frequency 30

 timeout 5000

 tag DHCP_Test

!

ip sla schedule 12 start-time now

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 this feature.

—


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 new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

—


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 Cisco IOS IP SLAs DHCP 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 Cisco IOS IP SLAs DHCP Operations

Feature Name
Releases
Feature Information

IP SLAs DHCP 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 Dynamic Host Control Protocol (DHCP) operation allows you to schedule and measure the network response time between a Cisco device and a DHCP server to obtain an IP address.


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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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