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CSS Content Load-Balancing Configuration Guide (Software Version 8.10)
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Index
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Preface
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Content Load-Balancing Overview
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Configuring Flow and Port Mapping Parameters
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Configuring Services
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Configuring Service, Global, and Script Keepalives
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Configuring Source Groups for Services
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Configuring Loads for Services
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Configuring Server/Application State Protocol for Server Load Balancing
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Configuring Dynamic Feedback Protocol for Server Load Balancing
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Configuring Owners
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Configuring Content Rules
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Configuring Sticky Parameters for Content Rules
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Configuring HTTP Header Load Balancing
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Configuring Caching
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Configuring Content Replication
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Table Of Contents
Configuring Service, Global, and Script Keepalives
Configuring Service Keepalives
Creating and Naming a Global Keepalive
Configuring a Global Keepalive IP Address
Configuring a Global Keepalive Description
Activating the Global Keepalive
Associating a Service with a Global Keepalive
Configuring Service and Global Keepalive Attributes
Configuring a Keepalive Frequency
Configuring a Keepalive Retry Period
Configuring the Maximum Number of Failures for a Keepalive
Configuring a TCP Keepalive with Graceful Socket Close (FIN)
Configuring a Keepalive Port Number
Configuring the HTTP Keepalive Method
Configuring a Keepalive HTTP Response Code
Configuring a Keepalive Hash Value
Showing Keepalive Configurations
Using Script Keepalives with Services
Script Keepalive Considerations
Viewing a Script Keepalive in a Service
Script Keepalives and Upgrading WebNS Software
Configuring Service, Global, and Script Keepalives
When you configure a service on the CSS, the CSS determines the state of the service by sending keepalive messages. By default, the CSS assigns each service with an ICMP keepalive with a frequency and retry period of 5 seconds, and a maximum failure rate of 3 times. To change the default keepalive settings for a service, you can configure individual keepalive attributes for the service or create a keepalive in keepalive mode and apply the service to it.
This chapter describes how to configure service, global, and script keepalives. Information in this chapter applies to all CSS models except where noted.
This chapter contains the following major sections to configure CSS keepalives:
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Configuring Service Keepalives
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CSS Keepalive Overview
The CSS supports a total of 2048 keepalives. These keepalives include:
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Global keepalives supersede the individual keepalive parameters configured in service mode. For information on configuring global keepalives, see the "Configuring Global Keepalives" section later in this chapter.
The CSS divides the keepalive types into two categories, Class A and Class B keepalives. The CSS supports a maximum of 2048 Class A keepalives. The CSS supports a maximum of 512 Class B keepalives.
Caution
Table 4-1 lists the keepalive types in each class, the maximum number of each type, and the maximum number of each keepalive type that can execute concurrently.
Table 4-1 Keepalive Class, Types, and Limitations
A
(The CSS limits 2048 keepalives per Class A.)
ICMP
2048
2048
HTTP-HEAD non-persistent1
2048
2048
SSL (Hello)
2048
2048
TCP
2048
2048
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(The CSS limits 512 keepalives per Class B.)
FTP
256
32
HTTP (GET persistent or non-persistent, or HEAD persistent)1
256
32
Script
256
16
1 An SSL proxy list contains a maximum of 256 SSL back-end servers. Therefore, the combined total number of Class A and Class B encrypted HTTP keepalives can only be 256.
When you configure a keepalive for a service (or associate a service with a global keepalive), the CSS periodically sends a message to the service based on the keepalive frequency to determine the state of the service. See the "Configuring a Keepalive Frequency" section. The CSS considers the service to be alive when a service responds to the keepalive message.
The CSS transitions the service to the dying state when the service fails to respond to a keepalive message. The CSS tests whether the failed service is functional by sending a keepalive message at time intervals based on the retry period. See the "Configuring a Keepalive Retry Period" section.
The CSS transitions the service to the down state if the service fails to respond a maximum number of retries to the keepalive message. See the "Configuring the Maximum Number of Failures for a Keepalive" section. Then the CSS removes the service from the load-balancing algorithm. The CSS continues to test whether the service is functional at time intervals based on the retry period.
Thus, using the default values of a 5-second keepalive frequency interval, a 5-second retry period interval, and maximum of three failures, a service can transition from the alive state to the dead state in 15 seconds; a 5-second interval between a keepalive response and the initial keepalive failure based on the keepalive frequency, and two failures, each occurring at 5-second intervals based on the retry period.
However, if the keepalives are Class B type keepalives, the time for a service to transition from an alive state to the dead state may take longer. This transition delay occurs because the CSS executes smaller numbers of Class B keepalives at the same time. For example, if you configure 256 HTTP-GET keepalives using the default values for frequency, retry period, and maximum failure, and all services fail, the time for all of the services to transition from the alive state to the dead state is 120 seconds; 32 services transitioning in 15 seconds followed by another 32 services until all 256 services have transitioned.
Configuring Service Keepalives
A service keepalive is the keepalive configured for a specific service. As you configure a service, you can configure its keepalive attributes. To configure keepalive attributes for a service, access Service configuration mode for the service and use the keepalive command. For information, see the "Configuring Service and Global Keepalive Attributes" section.
If you want to apply a CSS service to a global keepalive, see the "Configuring Global Keepalives" section.
After you configure a service including its keepalive attributes, you can activate the service. Activating a service puts it into the resource pool for load-balancing content requests and starts the keepalive function. For example, to activate service serv1, enter:
(config-service[serv1])# activeConfiguring Global Keepalives
A global keepalive allows you to configure keepalive attributes and apply multiple services to the keepalive. As long as one service is alive, the global keepalive service is alive. By having a single keepalive configuration for more than one service, you can reduce the amount of time to configure each service. Also the keepalive counts as one keepalive no matter how many services you apply to it.
Table 4-2 provides a quick overview of the basic steps required to configure a global keepalive. Each step includes the CLI command required to complete the task. For a complete description of each feature and all the options associated with the CLI commands, see the sections following Table 4-2.
Table 4-2 Global Keepalive Configuration Quick Start
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# config(config)#2.
(config)# keepalive keepimages(config-keepalive[keepimages])#3.
(config-keepalive[keepimages])# ip address 192.168.7.64.
(config-keepalive[keepimages])# type http5.
(config-keepalive[keepimages])# method get6.
(config-keepalive[keepimages])# uri "/index.html"7.
(config-keepalive[keepimages])# active8.
(config-service[imageserver1])# keepalive type named keepimages9.
(config-keepalive[keepimages])# show keepalive10.
(config-service[imageserver1])# show service
The following running-configuration example shows the results of entering the commands in Table 4-2 as shown in bold and any related commands.
!************************** SERVICE **************************server2ip address 10.3.6.1keepalive type named keepimagesactive!************************* KEEPALIVE *************************keepalive keepimagesip address 192.168.7.6type httpmethod geturi "/index.html"activeThe following sections provides information on:
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For information on configuring the keepalive attributes, see the "Configuring Service and Global Keepalive Attributes" section.
Creating and Naming a Global Keepalive
To create and name a global keepalive, use the keepalive command to access keepalive mode. You can access keepalive mode from circuit, global, interface, and IP configuration modes. The prompt changes to (config-keepalive [name]). You can also use this command from keepalive mode to access another keepalive.
Enter the name of the new keepalive you want to create or the name of an existing keepalive. Enter an unquoted text string with no spaces and a length of 1 to 31 characters. To see a list of existing keepalive names, use the keepalive ? command.
For example, to create the global keepalive keepimages, enter:
(config)# keepalive keepimagesWhen you access this mode, the prompt changes to (config-keepalive [keepimages]).
(config-keepalive[keepimages])#To remove an existing keepalive, enter:
(config)# no keepalive keepimagesConfiguring a Global Keepalive IP Address
The CSS sends global keepalives to a service that monitors the state of services assigned to it. Use the ip address command to specify the IP address where the keepalive messages are sent. Enter the IP address in dotted-decimal notation.
For example, to enter an IP address for keepalive keepimages, enter:
(config-keepalive[keepimages])# ip address 192.168.7.6Configuring a Global Keepalive Description
Optionally, you can provide a description for the global keepalive. To specify the description, use the description command. Enter the description as a quoted text string with a maximum of 64 characters, including spaces.
For example, to enter a description for the global keepalive keepimages, enter:
(config-keepalive[keepimages])# description "This keepalive is for the image servers"To delete a description, enter:
(config-keepalive[keepimages])# no descriptionActivating the Global Keepalive
Activating a keepalive enables the CSS to start sending keepalive messages to the IP address. Use the active command to activate the global keepalive.
For example, to activate the global keepalive keepimages, enter:
(config-keepalive[keepimages])# activeSuspending a Global Keepalive
To deactivate the keepalive, use the suspend command.
For example, enter:
(config-keepalive[keepimages])# suspendAssociating a Service with a Global Keepalive
To associate a service with a global keepalive, use the keepalive type named command. The service maintains the global keepalive attributes when you add the service to content rules.
For example, to associate imageserver1 with global keepalive keepimages, enter:
(config-service[imageserver1])# keepalive type named keepimagesConfiguring Service and Global Keepalive Attributes
The following sections describe the attributes you can configure for keepalives:
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Configuring a Keepalive Frequency
The keepalive frequency specifies the interval in seconds between keepalives messages sent to a service. Specify a frequency from 2 to 255 seconds. The default is 5 seconds.
Note
Note
For versions 7.20.1.04 and greater, the timeout is 2 seconds less than the keepalive frequency with a minimum of 1 second. From version 5.20 up to version 7.20.1.04, the timeout is one second less than the keepalive frequency.•
(config-service[serv1])# keepalive frequency 15To reset the frequency to its default value of 5, enter:
(config-service[serv1])# no keepalive frequency•
For example, to set the frequency time to 10 seconds, enter:
(config-keepalive[keepimages])# frequency 10To reset the frequency to its default value of 5, enter:
(config-keepalive[keepimages])# no frequencyConfiguring a Keepalive Retry Period
When a service has failed to respond to a given keepalive message (the service has transitioned to the dying state), the retry period specifies how frequently the CSS tests the service to see if it is functional. Enter the retry period as an integer from 2 to 255 seconds. The default is 5 seconds.
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(config-service[serv1])# keepalive retryperiod 60To reset the retry period to its default value of 5, enter:
(config-service[serv1])# no keepalive retryperiod•
(config-keepalive[keepimages])# retryperiod 60To reset the retry period to its default value of 5, enter:
(config-keepalive[keepimages])# no retryperiodConfiguring the Maximum Number of Failures for a Keepalive
The maximum failures is the number of times a service can fail to respond to a keepalive message before the CSS considers it offline. Specify a maximum failure number from 1 to 10. The default is 3.
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(config-service[serv1])# keepalive maxfailure 5To reset the maximum failure number to its default value of 3, enter:
(config-service[serv1])# no keepalive maxfailure•
(config-keepalive[keepimages])# maxfailure 7To reset the maximum failure number to its default value of 3, enter:
(config-keepalive[keepimages])# no maxfailureConfiguring a Keepalive Type
The keepalive type specifies the type of keepalive message assigned to the keepalive. The keepalive types include ICMP, HTTP-GET, HTTP-HEAD, TCP, FTP, SSL, and script keepalives. Also, with the use of an SSL module, you can configure encrypted HTTP-type keepalives to allow for HTTPS application verification.
For a service keepalive, a named keepalive type allows you to apply the service to a configured global keepalive.
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(config-service[serv1])# keepalive type ftp•
(config-keepalive[keepimages])# type tcpEach time you assign a keepalive type to a service or global keepalive, the CSS counts it as one keepalive.
Caution
The options for the keepalive type or type command are:
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The FTP keepalive type is a Class B type. The CSS supports a maximum of 256 FTP keepalives and concurrently executes a maximum of 32 keepalives of this type at a time.
When configuring the CSS for FTP keepalives, do not configure the keepalive frequency or the keepalive retryperiod to a value less than 15 seconds. Note that the CSS does not prevent you from configuring smaller values. Also, the default value for the keepalive frequency or the keepalive retryperiod is five seconds. You must use the keepalive frequency and keepalive retryperiod commands to override the defaults.
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For configuring the method for the HTTP keepalive type, see the "Configuring the HTTP Keepalive Method" section. The HTTP-HEAD persistent, and HTTP-GET persistent keepalive types are Class B types. Of each of these types, the CSS supports a maximum of 256 keepalives and concurrently executes a maximum of 32 keepalives at a time.
If an HTTP persistent keepalive fails to make a persistent connection, then it attempts to make a non-persistent connection. If the non-persistent connection succeeds, then the keepalive succeeds. At the next interval, the keepalive attempts a persistent connection.
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For configuring the method for the HTTP keepalive type, see the "Configuring the HTTP Keepalive Method" section. The HTTP-GET non-persistent keepalive type is a Class B type. Of this type, the CSS supports a maximum of 256 keepalives and concurrently executes a maximum of 32 keepalives at a time.
The HTTP-HEAD non-persistent keepalive type is a Class A type. The CSS supports a maximum of 2048 HTTP-HEAD non-persistent keepalives and concurrently executes a maximum of 2048 keepalives of this type at a time.
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For an SSL initiation server, the keepalives perform an HTTP GET or HEAD that is directed to the SSL module configured for the server. Then, the module connects to the configured server.
An SSL proxy list can consist of a maximum of 256 SSL back-end or initiation servers, thus the CSS supports a maximum of 256 encrypted keepalives.
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For information on configuring an SSL back-end or initiation server, refer to the Cisco Content Services Switch SSL Configuration Guide.
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The ICMP keepalive type is a Class A type. The CSS supports a maximum of 2048 ICMP keepalives and concurrently executes a maximum of 2048 keepalives of this type at a time.
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Before using this command, ensure that the global keepalive is activated through the (config-keepalive) active command. Assigning a service to a global keepalive overrides any keepalive properties you assigned in service mode. For information on creating a global keepalive, see the "Configuring Global Keepalives" section.
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The optional arguments variable passes arguments into the keepalive script. Enter a quoted text string with a maximum of 128 characters including spaces.
The use-output option allows the script to parse the output for each executed command. This optional keyword allows the use grep and file direction within a script. By default, the script does not parse the output. For details on using script keepalives, see the "Using Script Keepalives with Services" section later in this chapter.
The script keepalive type is a Class B type. The CSS supports a maximum of 256 script keepalives and concurrently executes a maximum of 16 keepalives of this type at a time.
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The SSL keepalive type is a Class A type. The CSS supports a maximum of 2048 SSL keepalives and concurrently executes a maximum of 2048 keepalives of this type at a time.
When the 11500 series CSS is using an SSL module, use the keepalive type of none. The SSL module is an integrated device in the CSS and does not require the use of keepalive messages for the service.
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The TCP keepalive type is a Class A type. The CSS supports a maximum of 2048 TCP keepalives and concurrently executes a maximum of 2048 keepalives of this type at a time.
Configuring a TCP Keepalive with Graceful Socket Close (FIN)
By default and in compliance with RFC 1122, the CSS sends a reset (RST) to close the socket on a server port for TCP keepalives. An RST is faster than a FIN, because an RST requires only one packet, while a FIN can take up to four packets. If your servers require a graceful closing of a socket using a FIN, you can configure a keepalive to send a FIN to close a socket.
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(config-service[serv1])# keepalive tcp-close finTo reset the keepalive to send an RST, enter:
(config-service[serv1])# keepalive tcp-close rst•
(config-keepalive[keepimages])# tcp-close finTo reset the keepalive to send an RST, enter:
(config-keepalive[keepimages])# tcp-close rstConfiguring a Keepalive Port Number
By default, the port number for keepalives is based on the keepalive type. If the keepalive type is:
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You can configure a port number from 0 to 65535.
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(config-service[serv1])# keepalive port 8080To reset the keepalive port to its default value, enter:
(config-service[serv1])# no keepalive port•
(config-keepalive[keepimages])# port 8080To reset the keepalive port to its default value, enter:
(config-keepalive[keepimages])# no portConfiguring the HTTP Keepalive Method
By default, when you configure an HTTP keepalive type, the CSS uses an HTTP-HEAD method. The CSS issues an HTTP-HEAD method to the service and a 200 OK status is required. The CSS does not compute a reference hash value for this type of keepalive. If the 200 OK status is not returned, the CSS considers the service down.
You can also configure an HTTP GET method. The CSS issues an HTTP GET method to the service, computes an MD5 (Message Digest Algorithm Version 5) hash value on the page, and stores the hash value as a reference hash. Subsequent GETs require a 200 OK status (HTTP command completed OK response) and the hash value to equal the reference hash value. If the 200 OK status is not returned, or if the 200 OK status is returned but the hash value is different from the reference hash value, the CSS considers the service down.
When you specify the content information of an HTTP Uniform Resource Identifier (URI) for an HTTP keepalive, the CSS calculates a hash value for the content. If the content information changes, the hash value no longer matches the original hash value and the CSS assumes that the service is down. To prevent the CSS from assuming that a service is down due to a hash value mismatch, specify the keepalive method as HTTP HEAD.
For information of configuring an HTTP response code, see the "Configuring a Keepalive HTTP Response Code" section. For information of configuring an HTTP URI, see the "Configuring a Keepalive URI" section.
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(config-service[serv1])# keepalive method getTo reset the HTTP keepalive method to HTTP HEAD, enter:
(config-service[serv1])# keepalive method head•
(config-keepalive[keepimages])# method getTo reset the HTTP keepalive method to HTTP HEAD, enter:
(config-keepalive[keepimages])# method headIf you change the keepalive method on an active service, make sure that you suspend and reactivate the service for the change to take effect.
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Configuring a Keepalive HTTP Response Code
By default, when the CSS issues an HTTP-HEAD keepalive, the CSS expects a response code of 200 in the response packet from the server it is querying. For HTTP-HEAD non-persistent keepalives, you can configure the CSS to expect a non-200 response code (for example, a 302 redirect response code). Enter the response code as an integer from 100 to 999.
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(config-service[serv1])# keepalive http-rspcode 302To reset the response code to its default value of 200, enter:
(config-service[serv1])# no keepalive http-rspcode•
(config-keepalive[keepimages])# http-rspcode 302To reset the response code to its default value of 200, enter:
(config-keepalive[keepimages])# no http-rspcodeConfiguring a Keepalive URI
When you configure an HTTP keepalive type, the CSS uses the URI string to determine if the service is alive. By default, the CSS uses the URI string to the root directory,"/". For an HTTP Get, the CSS uses the URI information to calculate the hash value. You can specify the URI content information for an HTTP keepalive.
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Enter the content information of the URI as a quoted text string with a maximum of 64 characters. Do not include the host information in the string. The CSS derives the host information from the service IP address and the keepalive port number.
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(config-service[serv1])# keepalive uri "/index.html"To clear the content information for the keepalive, enter:
(config-service[serv1])# no keepalive uri•
(config-keepalive[keepimages])# uri "/index.html"To clear the content information assigned to this keepalive, enter:
(config-keepalive[keepimages])# no uriConfiguring a Keepalive Hash Value
By default, the CSS uses the MD5 (Message Digest Algorithm Version 5) hash for an HTTP GET keepalive. The CSS compares the hash value against the computed hash value of all HTTP GET responses. A successful comparison causes the keepalive to maintain an Alive state.
For a service keepalive, use the service mode keepalive hash command to override the default MD5 hash. To configure the hash value for a service keepalive:
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(config)# service serv1(config-service[serv1])# ip address 10.0.3.21(config-service[serv1])# keepalive type http(config-service[serv1])# keepalive method get(config-service[serv1])# keepalive uri "/testpage.html"(config-service[serv1])# keepalive hash "1024b91e516637aaf9ffca21b4b05b8c"(config-service[serv1])# active2.
(config-service[serv1])# show keepaliveKeepalives:Name: serv1Index: 0 State: ALIVEDescription: Auto generated for service serv1Address: 10.0.3.21 Port: 80Type: HTTP:GET:/testpage.htmlHash: 1024b91e516637aaf9ffca21b4b05b8cFrequency: 5Max Failures: 3Retry Frequency: 5Dependent Services:3.
(config-service[serv1])# keepalive hash "1024b91e516637aaf9ffca21b4b05b8c"An excerpt of the service configuration from the running-config is as follows:
service serv1ip address 10.0.3.21keepalive type httpkeepalive method getkeepalive uri "/testpage.html"keepalive hash "1024b91e516637aaf9ffca21b4b05b8c"activeTo clear a hash value and return to the default hash value, enter:
(config-service[serv1])# no keepalive hashFor a global keepalive, use the hash command to override the default MD5 hash for an HTTP GET keepalive. To configure the hash value for a global keepalive:
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(config-keepalive[keepimages])# method get(config-keepalive[keepimages])# uri "/testpage.html"(config-keepalive[keepimages])# hash "1024b91e516637aaf9ffca21b4b05b8c"2.
(config)# service imageserver1(config-service[imageserver1])# ip address 10.0.3.21(config-service[imageserver1])# keepalive type named keepimages(config-service[imageserver1])# active3.
(config-keepalive[keepimages])# show keepaliveKeepalives:Name: imageserver1Index: 0 State: ALIVEDescription: Auto generated for service serv1Address: 10.0.3.21 Port:80Type: HTTP GET:/testpage.htmlHash: 1024b91e516637aaf9ffca21b4b05b8cFrequency: 5Max Failures: 3Retry Frequency: 5Dependent Services:4.
(config-keepalive[keepimages])# hash "1024b91e516637aaf9ffca21b4b05b8c"An excerpt of the service configuration from the running-config is as follows:
service imageserver1ip address 10.0.3.21keepalive type httpkeepalive method getkeepalive uri "/testpage.html"keepalive hash "1024b91e516637aaf9ffca21b4b05b8c"activeTo clear a hash value and return to the default hash value, enter:
(config-keepalive[keepimages])# no hashShowing Keepalive Configurations
To display keepalive information for a service, use the show service command. For more information on this command and what it displays, see the "Showing Service Configurations" section in Chapter 3, Configuring Services.
To display global keepalive configurations, use the show keepalive command. To display a list of existing keepalives, use the show keepalive ? command.
Note
Command Aborted!!! Configuration changed. Please reissue command.This command provides the following options:
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For example, enter:
(config)# show keepaliveKeepalives:Name: keepimages Index: 1 State: ALIVE ( ICP Check )Description: This keepalive is for image serversAddress: 172.16.1.7 Port: 80Type: HTTP:HEAD-302:/index.htmlFrequency: 5Max Failures: 3Retry Frequency: 5Dependent Services: imageserver1Name: rualive Index: 2 State: ALIVEDescription: Auto generated for service serv2Address: 172.16.1.8 Port: 80Type: HTTP:HEAD:/index.htmlFrequency: 5Max Failures: 3Retry Frequency: 5Dependent Services: serv2(config)# show keepalive-summaryKeepalives:Alive1 DOWN 192.25.1.7Alive2 ALIVE 192.25.1.8Table 4-3 describes the fields in the show keepalive command output.
Using Script Keepalives with Services
Script keepalives are scripts that you can create to provide custom keepalives for your specific service requirements. To create the scripts, use the rich CSS Scripting Language that is included in your CSS software. For details on using the CSS Scripting Language, including using socket commands and examples of keepalive scripts, refer to the Cisco Content Services Switch Administration Guide.
Currently, a CSS provides keepalives for FTP, HTTP, ICMP, SSL, and TCP. For information on configuring keepalive messages, see the "CSS Keepalive Overview" section earlier in this chapter.
Using script keepalives allow you to extend the CSS keepalive functionality beyond the default keepalives. For example, you can develop a script specifically to connect a CSS to a Post Office Protocol 3 (POP3) mail server.
Once you create a script offline, you can upload it to the CSS and configure the script keepalive option on a service.
The CSS supports a maximum of 256 script keepalives. If you specify a script to parse the output for each executed command, you can configure only 16 keepalives that use script output.
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Script Keepalive Considerations
When you configure a script keepalive, follow the same general guidelines as those for keepalive types, with the exceptions noted in these sections. For details on keepalives, see the "CSS Keepalive Overview" section earlier in this chapter.
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To see a complete list of all scripts available in the /<current running version>/script directory, press the Tab key or "?". Optionally, you can type a script name not found in the list, then you can upload the script later. You can manipulate scripts using the archive, clear, and copy commands. You can also upload a script from a local hard drive to the /script directory on the CSS, or download a script from the /script directory on the CSS to a local hard drive.
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Configuring Script Keepalives
Script keepalives are scripts that you can create to provide custom keepalives for your specific service requirements. Use the keepalive type script command to configure script keepalives. The syntax for this service configuration mode command is:
keepalive type script script_name {"arguments"} {use-output}
Enter the name of an existing script keepalive. The optional arguments variable passes arguments into the keepalive script. Enter a quoted text string with a maximum of 128 characters including spaces.
The optional use-output keyword allows the script to parse the output for each executed command. This optional keyword allows the use of grep and file direction within a script. You can configure a maximum of 16 script keepalives (out of a maximum of 255 script keepalives) to use script output. By default, the script does not parse the output.
For example, to configure a script keepalive named ap-kal-httplist, enter:
(config-service[serv1)# keepalive type script ap-kal-httplist "10.10.102.105 /default.htm"In the previous example, the keepalive command configures the serv1 service keepalive to be of type script with the script name ap-kal-httplist and the arguments "10.10.102.105 /default.htm". The output is not parsed by the script.
To disable a script keepalive on a service, enter:
(config-service[serv1])# keepalive type noneViewing a Script Keepalive in a Service
When you add a script keepalive to a service, the CSS recognizes that the script is the keepalive for the service in the show service screen. The script name appears in the Keepalive field, and any potential arguments appear directly below in the Script Arguments field. If there are no script arguments, then the Script Arguments field does not appear.
For example, enter:
(config-service[serv1])# show serviceName: serv1 Index: 1Type: Local State: AliveRule (10.10.102.105 ANY ANY)Session Redundancy: DisabledRedirect Domain:Redirect String: Keepalive: (SCRIPT ap-kal-httplist 10 3 5)Script Arguments: "10.10.102.105 /default.htm"Script Error: NoneScript Run Time: 1 secondScript Using Output Parsing: NoLast Clearing of Stats Counters 03/15/2002 13:45:01Mtu: 1500 State Transitions: 0Connections: 0 Max Connections: 0Total Connections: 0 Total Reused Conns: 0Weight: 1 Load: 2
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You can also use the show running-config command to display the script keepalive and its arguments.
For example, enter:
(config-service[serv1])# show running-configservice serv1ip address 10.10.102.105keepalive frequency 10keepalive type script ap-kal-httplist "10.10.102.105/default.htm"activeThe example above shows the script keepalive and arguments that have been configured on a service. If no arguments are specified in the script, then the quoted text following the script name will not appear.
Script Keepalive Status Codes
A script can return a status code of zero or non-zero. On a return of non-zero, the CSS flags the service state as Dying or Down; on a return of zero, the CSS flags the service state as Alive. For example, enter:
! Connect to the remote hostsocket connect host einstein port 25 tcp! Purposely failexit script 1Because the above script fails when it executes the exit command, the script returns a non-zero value. By default, the script will fail with a syntax error if the connect command fails. Be sure to check the logic of your scripts to ensure that the CSS returns the correct value.
Script Keepalives and Upgrading WebNS Software
When you upgrade the WebNS software in your CSS, the upgrade process creates a new /<current running version>/script directory. You must copy your custom scripts (including custom script keepalives) to the new /<current running version>/script directory so that the CSS can find them.
Use the following procedure to ensure that your custom script keepalives operate properly after upgrading the software.
1.
2.
3.
