Table Of Contents
Configuring Cisco IOS IP SLAs DNS Operations
Finding Feature Information
Contents
Information About IP SLAs DNS Operations
DNS Operation
How to Configure IP SLAs DNS Operations
Configuring an IP SLAs DNS Operation on the Source Device
Configuring a Basic DNS Operation on the Source Device
Configuring a DNS Operation with Optional Parameters on the Source Device
Scheduling IP SLAs Operations
Restrictions
Examples
Troubleshooting Tips
What to Do Next
Configuration Examples IP SLAs DNS Operations
Example: Configuring a DNS Operation
Additional References
Related Documents
Standards
MIBs
RFCs
Technical Assistance
Feature Information for IP SLAs DNS Operations
Configuring Cisco IOS IP SLAs DNS Operations
First Published: August 14, 2006
Last Updated: January 6, 2011
This module describes how to configure the Cisco IOS IP Service Level Agreements (SLAs) Domain Name System (DNS) operation to measure the difference between the time taken to send a DNS request and receive a reply. This module also demonstrates how the results of the DNS operation can be displayed and analyzed to determine the DNS lookup time which is a critical element for determining the performance of a DNS or web server.
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 DNS 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 IP SLAs DNS Operations
•How to Configure IP SLAs DNS Operations
•Configuration Examples IP SLAs DNS Operations
•Additional References
•Feature Information for IP SLAs DNS Operations
Information About IP SLAs DNS Operations
•DNS Operation
DNS Operation
The DNS operation measures the difference between the time taken to send a DNS request and receive a reply. DNS is used in the Internet for translating names of network nodes into addresses. The IP SLAs DNS operation queries for an IP address if you specify a host name, or queries for a host name if you specify an IP address.
In Figure 1 Router B is configured as the source IP SLAs device and a DNS operation is configured with the DNS server as the destination device.
Figure 1 DNS Operation
Connection response time is computed by measuring the difference between the time taken to send a request to the DNS server and the time a reply is received by Router B. The resulting DNS lookup time can help you analyze your DNS performance. Faster DNS lookup times translate to a faster web server access experience.
How to Configure IP SLAs DNS Operations
•Configuring an IP SLAs DNS Operation on the Source Device (required)
•Scheduling IP SLAs Operations (required)
Configuring an IP SLAs DNS Operation on the Source Device
Note There is no need to configure an IP SLAs responder on the destination device.
Perform one of the following tasks:
•Configuring a Basic DNS Operation on the Source Device
•Configuring a DNS Operation with Optional Parameters on the Source Device
Configuring a Basic DNS Operation on the Source Device
SUMMARY STEPS
1. enable
2. configure terminal
3. ip sla operation-number
4. dns {destination-ip-address | destination-hostname} name-server ip-address [source-ip {ip-address | hostname} source-port port-number]
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
|
dns {destination-ip-address |
destination-hostname} name-server ip-address
[source-ip {ip-address | hostname} source-port
port-number]
Example:
Router(config-ip-sla)# dns host1 name-server
172.20.2.132
|
Defines a DNS operation and enters IP SLA DNS configuration mode.
|
Step 5
|
frequency seconds
Example:
Router(config-ip-sla-dns)# frequency 60
|
(Optional) Sets the rate at which a specified IP SLAs operation repeats.
|
Step 6
|
end
Example:
Router(config-ip-sla-dns)# end
|
Exits to privileged EXEC mode.
|
Configuring a DNS Operation with Optional Parameters on the Source Device
SUMMARY STEPS
1. enable
2. configure terminal
3. ip sla operation-number
4. dns {destination-ip-address | destination-hostname} name-server ip-address [source-ip {ip-address | hostname} source-port port-number]
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
|
dns {destination-ip-address |
destination-hostname} name-server ip-address
[source-ip {ip-address | hostname} source-port
port-number]
Example:
Router(config-ip-sla)# dns host1 name-server
172.20.2.132
|
Defines a DNS operation and enters IP SLA DNS configuration mode.
|
Step 5
|
history buckets-kept size
Example:
Router(config-ip-sla-dns)# 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-dns)# 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-dns)# 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-dns)# 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-dns)# 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-dns)# 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-dns)# 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-dns)# 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-dns)# 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-dns)# tag
TelnetPollServer1
|
(Optional) Creates a user-specified identifier for an IP SLAs operation.
|
Step 15
|
threshold milliseconds
Example:
Router(config-ip-sla-dns)# 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-dns)# 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-dns)# 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 11 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 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 DNS operation number 11.
Router# show ip sla configuration 11
Complete Configuration Table (includes defaults)
Type of operation to perform: dns
Target address: www.cisco.com
Operation timeout (milliseconds): 9000
Operation frequency (seconds): 60
Next Scheduled Start Time: Start Time already passed
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 IP SLAs DNS Operations
•Example: Configuring a DNS Operation
Example: Configuring a DNS Operation
The following example shows how to configure a DNS operation as shown in Figure 1 from Router B to the DNS server (IP address 172.20.2.132). The operation is scheduled to start immediately. In this example, the target address is a hostname and the DNS operation will query the DNS server for the IP address associated with the hostname host1. No configuration is required at the DNS server.
Router B Configuration
dns host1 name-server 172.20.2.132
ip sla schedule 11 start-time now
Additional References
Related Documents
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 IP SLAs DNS 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 the IP SLAs DNS Operation
Feature Name
|
Releases
|
Feature Information
|
IP SLAs DNS 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 Domain Name System (DNS) operation allows you to measure the difference between the time taken to send a DNS request and receive a reply.
|
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)
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.
© 2006-2010 Cisco Systems, Inc. All rights reserved.
