Configuring an IP SLAs HTTP Operations

This chapter describes how to configure an HTTP IP Service Level Agreements (IP SLAs) operation.

This chapter includes the following sections:

Configuring an IP SLAs HTTP Operation

This chapter describes how to configure an IP Service Level Agreements (SLAs) HTTP operation to monitor the response time between a Cisco device and an HTTP server to retrieve a web page. The IP SLAs HTTP operation only supports the normal GET requests.

About IP SLAs HTTP Operations

An HTTP request can be made through a proxy server.

The HTTP operation measures the round-trip time (RTT) between a Cisco device and an HTTP server to retrieve a web page. The HTTP server response time measurements consist of three types:

  • DNS lookup - RTT taken to perform a domain name lookup.

  • TCP Connect - RTT taken to perform a TCP connection to the HTTP server.

  • HTTP transaction time - RTT taken to send a request and get a response from the HTTP server. The operation retrieves only the home HTML page.

The HTTP operation first performs the DNS operation and measures the DNS RTT. Once the domain name is found, the HTTP operation performs a TCP Connect operation to the appropriate HTTP server. The HTTP operation then measures the TCP connect RTT. Finally, the HTTP operation sends a HTTP request to retrieve the home HTML page from the HTTP server. The HTTP operation then measures the RTT to retrieve the home HTML page. The HTTP operation makes another last measurement called "the time to first byte". This measures the time from the start of the TCP Connect operation to the first HTML byte retrieved by the HTTP operation. The total HTTP RTT is a sum of the DNS RTT, the TCP Connect RTT, and the HTTP RTT. You can use the total HTTP RTT to monitor Web server performance levels by determining the RTT taken to retrieve a web page.

For GET requests, IP SLAs will format the request based on the specified URL.

Restrictions for IP SLAs HTTP Operations

IP SLAs HTTP operations have the following restrictions:

  • IP SLAs HTTP operations only support the HTTP GET probe on the Cisco Nexus 9300 and 9500 Series switches beginning with Cisco NX-OS Release 7.0(3)I6(1).

  • Setting the frequency to less than 60 seconds increases the number of packets sent. However, this might impact the performance of IP SLA operations when a scheduled operation has the same start time.

Configuring a Basic HTTP GET Operation

The HTTP GET method retrieves information (in the form of an entity) as identified by the Request-URL.

SUMMARY STEPS

  1. configure terminal
  2. ip sla operation-number
  3. http {get | url [version version-number ] [source-ip {ip-address | hostname }] [source-port port-number ] [cache {enable | disable }] [proxy proxy-url]
  4. frequency seconds
  5. end

DETAILED STEPS

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

ip sla operation-number

Example:

switch(config)# ip sla 10

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

Step 3

http {get | url [version version-number ] [source-ip {ip-address | hostname }] [source-port port-number ] [cache {enable | disable }] [proxy proxy-url]

Example:

switch(config-ip-sla-http)# http get http://198.133.219.25

Defines an HTTP operation and enters IP SLA configuration mode.

Step 4

frequency seconds

Example:

switch(config-ip-sla-http)# frequency 90

(Optional) Sets the repeat rate for a specified IP SLAs HTTP operation. The default and minimum frequency value for an IP SLAs HTTP operation is 60 seconds.

Step 5

end

Example:

switch(config-ip-sla-http)# end

Exits IP SLA config mode.

Configuring a HTTP GET Operation with Optional Parameters

SUMMARY STEPS

  1. configure terminal
  2. ip sla operation-number
  3. http {get | url [version version-number ] [source-ip {ip-address | hostname }] [source-port port-number ] [cache {enable | disable }] [proxy proxy-url]
  4. history buckets-kept size
  5. history distributions-of-statistics-kept size
  6. history enhanced [interval seconds] [buckets number-of-buckets]
  7. history filter { none| all | overThreshold | failures}
  8. frequency seconds
  9. history hours-of-statistics-kept hours
  10. history live-kept lives
  11. owner owner-id
  12. history statistics-distribution-interval milliseconds
  13. tag text
  14. threshold milliseconds
  15. timeout milliseconds
  16. tos number
  17. end

DETAILED STEPS

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

ip sla operation-number

Example:

switch(config)# ip sla 10

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

Step 3

http {get | url [version version-number ] [source-ip {ip-address | hostname }] [source-port port-number ] [cache {enable | disable }] [proxy proxy-url]

Example:

switch(config-ip-sla)# http get http://198.133.219.25

Defines an HTTP operation and enters IP SLA configuration mode.

Step 4

history buckets-kept size

Example:

switch(config-ip-sla-http)# history buckets-kept 25

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

Step 5

history distributions-of-statistics-kept size

Example:

switch(config-ip-sla-http)# history distribution-of-statistics-kept 5

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

Step 6

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

Example:

switch(config-ip-sla-http)# history enhanced interval 900 buckets 100

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

Step 7

history filter { none| all | overThreshold | failures}

Example:

switch(config-ip-sla-http)# history filter failures

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

Step 8

frequency seconds

Example:

switch(config-ip-sla-http)# frequency 90

(Optional) Sets the repeat rate for specified IP SLAs HTTP operation. The default and minimum frequency value for an IP SLAs HTTP operation is 60 seconds.

Step 9

history hours-of-statistics-kept hours

Example:

switch(config-ip-sla-http)# history hours-of-statistics-kept 4

(Optional) Defines the number of hours to maintain for an IP SLAs operation.

Step 10

history live-kept lives

Example:

switch(config-ip-sla-http)# history lives-kept 5

(Optional) Defines the number of lives to maintain for an IP SLAs operation.

Step 11

owner owner-id

Example:

switch(config-ip-sla-http)# owner admin

(Optional) Configures the simple Management Network Protocol (SNMP) for an IP SLAs operation.

Step 12

history statistics-distribution-interval milliseconds

Example:

switch(config-ip-sla-http)# history statistics-distribution-interval 10

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

Step 13

tag text

Example:

switch(config-ip-sla-http)# tag TelnetPollServer1

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

Step 14

threshold milliseconds

Example:

switch(config-ip-sla-http)# threshold 10000

(Optional) Sets the upper threshold value to calculate network monitoring statistics of an IP SLAs operation.

Step 15

timeout milliseconds

Example:

switch(config-ip-sla-http)# timeout 10000

(Optional) Set the maximum response time from a request packet for an IP SLAs operation.

Step 16

tos number

Example:

switch(config-ip-sla-http)# tos 160

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

Step 17

end

Example:

switch(config-ip-sla-http)# end

Exits IP SLA config mode.

Scheduling IP SLAs Operations

Before you begin

  • Configure all the IP Service Level Agreements (SLAs) operations before you schedule them.

  • Check that the frequency of all operations in a multioperation group are the same.

  • Limit the maximum number of operation ID numbers, including commas (,), in a multioperation group to 125 characters.

  • Confirm the following before scheduling operations:

    • Configure any IP SLA operation before scheduling.

    • Configure the frequency of all the scheduled operations in a multioperation group to be the same.

    • The list of one or more operation ID numbers added to a multioperation group is limited to a maximum number of 125 characters in length, including commas (,).

SUMMARY STEPS

  1. configure terminal
  2. Select one of the following commands based on the number of IP SLAs operations you wish to schedule.
    • 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 {foreever }] start-time {hh:mm [:ss] [month day | day month] |pending|now |after hh:mm [:ss]}]
  3. show ip sla group schedule
  4. show ip sla group configuration
  5. end

DETAILED STEPS

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

Select one of the following commands based on the number of IP SLAs operations you wish to schedule.

  • 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 {foreever }] start-time {hh:mm [:ss] [month day | day month] |pending|now |after hh:mm [:ss]}]

Example:

switch (config-ip-sla-http)# ip sla schedule 10 life forever start-time now
switch (config-ip-sla-http)# ip sla group schedule 10 life schedule-period frequency
switch (config-ip-sla-http)# ip sla group schedule 1.3.4.6-9 life forever start-time now
switch (config-ip-sla-http)# ip sla group schedule 1.3.4.6-9 schedule-period 50 frequency range 80-100

The first command configures the scheduling parameters for an individual IP SLAs operation.

The second command specifies the IP SLAs operation group number and the range of operation numbers for a multioperation scheduler.

Step 3

show ip sla group schedule

Example:

switch(config-ip-sla-http)# show ip sla group schedule

(Optional) Displays the IP SLAs group schedule details.

Step 4

show ip sla group configuration

Example:

switch(config-ip-sla-http)# show ip sla group configuration

(Optional) Displays the IP SLAs configuration details.

Step 5

end

Example:

switch(config-ip-sla-http)# end

Exits IP SLA config mode.

Troubleshooting Tips

If the IP SLAs operation is not generating statistics, configure using the verify-data command. This enables a check for response corruption per operation. Make sure that the IP SLAs operation is not running, otherwise the verify-data command generates unnecessary overhead.

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