Catalyst 6500 Series Switch Content Switching Module (CSM) Installation and Configuration Note Software Release 3.1

Configuring Probes for Health Monitoring
Configuring Route Health Injection
- Understanding RHI
- Configuring RHI for Virtual Servers
Configuring Inband Health Monitoring
- Understanding Inband Health Monitoring
- Configuring Inband Health Monitoring
Configuring HTTP Return Code Checking
- Understanding HTTP Return Code Checking
- Configuring HTTP Return Code Checking
Configuring Scripts for Health Monitoring Probes

Configuring Health Monitoring

This chapter describes how to configure the health monitoring on the CSM and contains these sections:

•Configuring Probes for Health Monitoring

•Configuring Route Health Injection

•Configuring Inband Health Monitoring

•Configuring HTTP Return Code Checking

•Configuring Scripts for Health Monitoring Probes

Configuring Probes for Health Monitoring

Configuring probes to the real servers allows you to determine if the real servers are operating correctly. A real server's health is categorized as follows:

•Active—The real server responds appropriately.

•Suspect—The real server is unreachable or returns an invalid response. The probes are retried.

•Failed—The real server fails to reply after a specified number of consecutive retries. You are notified and the CSM adjusts incoming connections accordingly. Probes continue to a failed server until the server becomes active again.

The CSM supports probes used to monitor real servers. Configuring a probe involves the following:

•Entering the probe submode

•Naming the probe

•Specifying the probe type

The CSM supports a variety of probe types that monitor real servers, including FTP, DNS, or HTTP.

Note By default, no probes are configured on the CSM.

To set up a probe, you must configure it by naming the probe and specifying the probe type while in probe submode.

After configuring a probe, you must associate it with a server farm for the probe to take effect. All servers in the server farm receive probes of the probe types that are associated with that server farm. You can associate one or more probe types with a server farm.

If you assign a port number when configuring either the real server or the virtual server you do not need to specify a port number when you configure a probe. The probe inherits the port number from the real or virtual server configuration.

You can override the real server's and virtual server's port information by explicitly specifying a port to probe in the health probe configuration using the optional health probe port feature. This feature allows you to set a port for use by the health probes when no port is specified either in the real server or virtual server.

After you configure a probe, associate single or multiple probes with a server farm. All servers in the server farm receive probes of the probe types that are associated with that pool.

Note If you associate a probe of a particular type with a server farm containing real servers that are not running the corresponding service, the real servers send error messages when they receive a probe of that type. This action causes the CSM to place the real server in a failed state and disable the real server from the server farm.

To specify a probe type and name, perform this task:


	Command	Purpose
Step 1	Router(config-module-csm)# probe probe-name {http \| icmp \| telnet \| tcp \| ftp \| smtp \| dns \| kal-ap-upd}	Specifies a probe type and a name¹ ². •probe-name is the name of the probe being configured; it has a character string of up to 15 characters. •http creates an HTTP probe with a default configuration. •icmp creates an ICMP probe with a default configuration. •telnet creates a Telnet probe with a default configuration. •tcp creates a TCP probe with a default configuration. •ftp creates an FTP probe with a default configuration. •smtp creates an SMTP probe with a default configuration. •dns creates a DNS probe with a default configuration. •kal-ap-upd creates a GSLB target probe.
Step 2	Router(config-slb-probe-tcp)# port port-number: 1-MAXUSHORT	Configure an optional port for a probe³.
Step 3	Router# show module csm slot probe	Displays all probes and their configuration.

¹The no form of this command removes the probe type from the configuration.

²Inband health monitoring provides a more scalable solution if you are receiving performance alerts.

³The port command does not exist for the ICMP or PING health probe.

Note When you specify a probe name and type, it is initially configured with the default values. Enter the probe configuration commands to change the default configuration.

This example shows how to configure a probe:

Router(config-module-csm)# probe probe1 tcp

Router(config-slb-probe-tcp)# interval 120

Router(config-slb-probe-tcp)# retries 3

Router(config-slb-probe-tcp)# failed 300

Router(config-slb-probe-tcp)# open 10

Router(config-slb-probe-tcp)# serverfarm sf4

Router(config-slb-sfarm)# real 10.1.0.105

Router(config-slb-real)# inservice

Router(config-slb-real)# probe probe1

Router(config-slb-sfarm)# vserver vs4

Router(config-slb-vserver)# virtual 10.1.0.84 tcp 80

Router(config-slb-vserver)# serverfarm sf4

Router(config-slb-vserver)# inservice

Router(config-slb-vserver)# end

Note There are two different timeout values: open and receive. The open timeout specifies how many seconds to wait for the connection to open (that is, how many seconds to wait for SYN ACK after sending SYN). The receive timeout specifies how many seconds to wait for data to be received (that is, how many seconds to wait for an HTTP reply after sending a GET/HHEAD request). Because TCP probes close as soon as they open without sending any data, the receive timeout is not used.