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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 Content Replication
Configuring Demand-Based Content Replication
Demand-Based Content Replication Quick Start
Specifying Service Type for Replication
Configuring FTP Access for Content Replication
Configuring Content Staging and Replication
Content Staging and Replication Quick Start
Configuring FTP Access for Publishing and Subscribing
Configuring a Publishing Service
Displaying Publisher Configurations
Configuring a Subscriber Service
Displaying Subscriber Configurations
Configuring a Content Rule for Content Staging and Replication
Configuring Publisher Content Replication
Configuring File-Error Handling for Content Replication
Configuring Content Replication
This chapter describes how to configure demand-based content replication and content staging and replication.
Note
The Demand-Based Content Replication and the Content Staging and Replication features require the CSS Enhanced feature set license.
The information in this chapter applies to all CSS models, except where noted.
This chapter contains the following major sections:
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Configuring Demand-Based Content Replication
One of the biggest challenges for a Web site includes managing unpredictable traffic and flash crowds caused by sudden hot content. Using demand-based content replication, the CSS can track content requests and identify and replicate hot content to overflow Web servers or caches dynamically.
Note
Demand-based content replication is traffic-based. Increases in the flow of traffic make content available automatically at replication services. When you configure demand-based content replication, the CSS automatically:
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The following sections describe how to configure service replication:
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Demand-Based Content Replication Quick Start
Table 14-1 provides a quick overview of the steps required to configure demand-based content replication. 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 command, see the sections following Table 14-1.
Table 14-1 Demand-Based Content Replication Configuration Quick
Start1.
# config (config)#2.
(config)# ftp-record myftprecord 172.16.6.58 bobo "secret" /3.
(config)# owner arrowpoint(config-owner[arrowpoint])#4.
(config-owner[arrowpoint])# content rule1(config-owner-content[arrowpoint-rule1])#5.
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(config-owner-content[arrowpoint-rule1])# hotlist interval 106.
(config)# service local_serv(config-service[local_serv])# exit(config)# service rep_serv(config-service[rep_serv])# type rep-cache-redir7.
(config-service[rep-serv])# access ftp myftprecord8.
# (config)# cmd-sched record content_replication 30 21 3 6 1
The following running-configuration example shows the results of entering the commands in Table 14-1.
!************************** SERVICE **************************service local_servservice rep_servtype rep-cache-rediraccess ftp myftprecord!*************************** OWNER ***************************owner arrowpointaddress "200 Beaver Brook Road, Boxborough, MA 01719"content rule1vip address 192.1.1.100protocol tcpport 80hotlist interval 10Configuring Hot Lists
Defining hot-list attributes for a content rule enables you to determine which content is heavily accessed. With this information, you can accurately determine which content should be replicated. The CSS enables you to configure hot-list attributes for content rules. Use the hotlist command to define a list that captures the names of the most requested content (hot content).
Note
You can configure the following hot-list attributes for specific content from config-owner-content mode:
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(config-owner-content[arrowpoint-rule1])# hotlistTo disable a hot list, enter:
(config-owner-content[arrowpoint-rule1])# no hotlist•
(config-owner-content[arrowpoint-rule1])# hotlist interval 10To restore the hot-list interval to the default of 1, enter:
(config-owner-content[arrowpoint-rule1])# no hotlist interval•
(config-owner-content[arrowpoint-rule1])# hotlist size 20To restore the hot-list size to the default of 10, enter:
(config-owner-content[arrowpoint-rule1])# no hotlist size•
(config-owner-content[arrowpoint-rule1])# hotlist threshold 9To restore the hot-list threshold default of 0, enter:
(config-owner-content[arrowpoint-rule1])# no hotlist threshold•
(config-owner-content[arrowpoint-rule1])# hotlist type hitCountTo restore the hot-list type to the default setting hitCount, enter:
(config-owner-content[arrowpoint-rule1])# no hotlist typeSpecifying Service Type for Replication
Within a replication configuration, you must configure at least two servers: one local and one replication type. The CSS provides the following service types specific to replication:
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When you specify a service as type rep-cache-redir, the CSS uses the service as a cache server, caching hot content and sending requests to it. Once content is cached on the replication server, the CSS creates a dynamic content rule for the hot content and a dynamic service.
The CSS deletes the hot content when the max-age time has elapsed. See the section, "Configuring Max Age" later in this chapter.
For example:
(config)# service serv1 (config-service[serv1])# type rep-cache-redirWhen you specify a service as type rep-store, the CSS replicates hot content on the service. Once content is replicated on the replication server, the CSS creates a dynamic content rule for the hot content automatically. The dynamic content rule inherits all the attributes of the existing rule with the following changes:
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The CSS deletes the dynamic content rule after the maximum age time elapses. See the following section, "Configuring Max Age". The CSS lists the dynamic content rule in the show rule display. It is not displayed in the running- or startup-config files.
Note
For example:
(config)# service serv1 (config-service[serv1])# type rep-storeConfiguring Max Age
To define the maximum age for replicated objects on services defined as type rep-cache-redir, rep-store, or rep-store-redir, use the max age command. Enter the maximum age in minutes from 1 to 1440. The default is 120.
For example:
(config-service[serv1])# max age 10To set the maximum age for replicated objects to its default value of 120, enter:
(config-service[serv1])# no max ageConfiguring Max Content
To define the maximum pieces of content for replication on services defined as type rep-cache-redir, rep-store, or rep-store-redir, use the max content command. Enter the maximum pieces of content from 1 to 65535. The default is 100.
For example:
(config-service[serv1])# max content 50To set the maximum content to its default value of 100, enter:
(config-service[serv1])# no max contentConfiguring Max Usage
to define the maximum disk space allowed for replication on services defined as type rep-cache-redir, rep-store, or rep-store-redir, use the max usage command. Enter the disk space for a service from 1 to 1000 MB. The default is 1.
For example:
(config-service[serv1])# max usage 100To set the maximum disk space to its default value of 1, enter:
(config-service[serv1])# no max usageConfiguring FTP Access for Content Replication
You must associate an FTP access mechanism for each service that offers publishing services. Use the access ftp command to associate an FTP access mechanism with a service for demand-based replication activities.
When you use this command to associate an FTP access mechanism with a service, the base directory of an existing FTP record becomes the tree root. To maintain coherent mapping between WWW daemons and FTP daemons, make the FTP access base directory equivalent to the WWW daemon root directory as seen by clients.
Enter the access ftp_record as the name of an existing FTP record. Enter the FTP record name as an unquoted text string with no spaces.
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For example:
(config-service[serv1])# access ftp myftprecordTo remove a service access mechanism, enter:
(config-service[serv1])# no access myftprecord
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Creating an FTP Record
To create a File Transfer Protocol (FTP) record file to use when accessing an FTP server from the CSS, use the ftp-record command. The syntax for this global configuration mode command is:
ftp-record ftp_record ip_address or hostname username ["password"|des-password des_password] base_directory
The variables are:
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16 characters.•
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For example:
(config)# ftp-record myftprecord 172.16.6.58 bobo "secret" /To delete an FTP record file from the CSS, use the no ftp-record command and the ftp record name. For example:
(config)# no ftp-record myftprecordConfiguring Content Staging and Replication
The CSS supports content staging and replication using Publisher and Subscriber services. With this feature, the CSS takes content (for example, a file, multiple files, or complete directories) that you post to the staging publisher server and replicates the content dynamically to multiple subscriber servers based on one of the following triggers:
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The CSS detects changes to specific content by performing an FTP-based examination of filenames, sizes, and file dates. The CSS performs this examination based on the configured publisher interval or by the replicate command. The subscriber knows how to interface to the publisher by virtue of the 'access ftp' associated with the publisher-designated service.
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For new configurations, after software upgrades, or after adding a new subscriber, we recommend that you use the replicate command with the force option to ensure that the publisher and the subscriber information is synchronized. Thereafter, the CSS automatically updates the associated subscribers with any file or directory changes that occur on the publisher according to the configured publisher interval.
If a CSS detects any differences on the publisher when you reboot the CSS on the same software image with content replication configured, the publisher applies those differences to the associated subscribers to maintain synchronization. This behavior assumes that you have previously synchronized the publisher and the subscriber.
Note
The content staging and replication feature does not limit the size of files to be replicated. However, larger files take a longer time to be replicated. The maximum number of replicated files is 1,000,000. Note that the CSS does not store replicated files on its disk. The CSS creates a virtual path to transfer data between the publisher and subscriber services. Buffering is limited to the default buffering associated with TCP.
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You can configure the CSS to continually update content that has been replicated. For example, the CSS can replicate content associated with a breaking news story. You can post updates to the staging server and the updates will be replicated to all distributed locations automatically.
Publisher and subscriber services are usually defined as type local. There is no need to change the service type.
The following sections describe how to configure publisher and subscriber services:
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Content Staging and Replication Quick Start
Table 14-2 provides a quick overview of the steps required to configure demand-based content replication. 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 command, see the sections following Table 14-2.
Table 14-2 Content Staging and Replication Configuration Quick Start
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# config (config)#2.
(config)# ftp-record myftprecord 172.16.6.58 bobo "secret" /3.
(config)# service pubserver (config-service[pubserver])#4.
(config-service[pubserver])# publisher5.
(config-service[pubserver])# publisher interval 1206.
(config-service[pubserver])# access ftp myftprecord7.
(config)# service subserver (config-service[subserver])#8.
(config-service[subserver])# subscriber pubserver9.
(config-owner-content[arrowpoint-products.html])# url "/announcements/*.html"For a complete description of configuring URLs, refer to Chapter 10, Configuring Content Rules.
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(config-owner-content[arrowpoint-products.html)# add service subserver11.
# replicate pubserver12.
# (config)# cmd-sched record content_replication 30 21 3 6 113.
# show publisher14.
The following running-configuration example shows the results of entering the commands in Table 14-2.
!************************** SERVICE **************************service pubserverpublisher interval 120access ftp myftprecordservice subserversubscriber pubserver!*************************** OWNER ***************************owner arrowpointaddress "200 Beaver Brook Road, Boxborough, MA 01719"content products.htmlprotocol tcpport 80url "/announcements.html"add service subserverConfiguring FTP Access for Publishing and Subscribing
You must associate an access mechanism for each service that offers publishing services and for each service that you configure as a subscriber. Use the access ftp command to associate an access mechanism with a service for use during publishing and subscribing activities.
Enter the FTP record as the name of an existing FTP record. Enter the FTP record name as an unquoted text string with no spaces.
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The syntax for this service mode command is:
(config-service[pubserver])# access ftp myftprecordTo remove a service access mechanism, enter:
(config-service[pubserver])# no access ftpConfiguring a Publishing Service
A publishing service synchronizes content among associated subscriber services.
To move the content during publishing activities, you must configure an access mechanism for the publisher service. Use the (config-service) access ftp command defined earlier in this chapter to configure a mechanism for the publisher service.When you define the interval to synchronize the subscriber, the interval begins at the time you issue the command. Subscribers that are unavailable for synchronization are placed in an offline state and retried until the operation is completed.
There is no limit on the size of the files that a CSS can replicate between a publisher and a subscriber. When transferring data between a publisher and a subscriber, a CSS creates a virtual pipe so that the replicated files never use the CSS disk. The CSS uses the default buffering associated with the TCP communications stack.
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Use the publisher command to configure a service as a publishing service. A publishing service can be any type of service that applies to your applications (for example, local or proxy-cache). For a complete description of service types, see Chapter 3, Configuring Services.
The syntax and options for this service mode command are:
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To configure publishing on a service, enter:
(config-service[pubserver])# publisherTo remove publishing on a service, enter:
(config-service[pubserver])# no publisherTo configure a publisher resynchronization interval, enter:
(config-service[pubserver])# publisher interval 120To disable the publisher resynchronization interval by setting it to its default of 0, enter:
(config-service[pubserver])# no publisher intervalDisplaying Publisher Configurations
Use the show publisher command to display the operational status of the publishing service and content information. The options and syntax are:
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To display information about the publishing services, enter:
(config-service)# show publisherTable 14-3 describes the fields in the show publisher output.
Configuring a Subscriber Service
To configure a service as a subscriber to a publishing service, use the subscriber command . You can define a maximum of 31 subscribers per publisher.
You must configure an access mechanism for each subscriber. Use the (config-service) access ftp command defined earlier in this chapter to configure an access mechanism for each subscriber.
To configure a service as a subscriber to a publishing service, enter:
(config-service[subserver])# subscriber pubserverTo unsubscribe the service from a publishing service, enter:
(config-service[subserver])# no subscriber
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Displaying Subscriber Configurations
Use the show subscriber command to display the operational status of the subscriber services. The syntax is:
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To display information about the subscriber services, enter:
(config)# show subscriberTable 14-4 describes the fields in the show subscriber output.
Configuring a Content Rule for Content Staging and Replication
When you configure content staging and replication, you must configure a URL in a content rule to define which files you want replicated. Then add the subscriber services to the content rule.
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For example, to specify a URL that matches all requests for content in the announcements directory with .html extensions, enter:
(config-owner-content[arrowpoint-products.html])# url "/announcements/*.html"For a complete description of configuring URLs, see Chapter 10, Configuring Content Rules.
To add the subscriber services to the content rule, use the add service command. For example:
(config-owner-content[arrowpoint-products.html)# add service subserverConfiguring Publisher Content Replication
To start replicating content between a publisher and all associated subscribers immediately, use the replicate command. You can use this command to replicate to subscribers changes in content on the publisher or to force resynchronization of all content to new subscribers.
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Enter the publisher_name as the name of the existing publisher. Enter the subscriber_name as the name of the subscriber associated with the publisher service.
The syntax and options are:
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We recommend that you do not use the force option for routine content replication. The force option does not scan the publisher directory structure and, therefore, does not account for files added to or deleted from the publisher directory structure since the last scan. If you want to use the force option in a situation other than the ones listed above, manually replicate the content first to allow the CSS to scan the publisher tree, then apply the force option.
For example:
# replicate pubserverConfiguring File-Error Handling for Content Replication
Under certain rare circumstances, it is possible for the CSS to encounter a file error during content replication. A file error can occur when an application or a user deletes a file from the publisher tree during a replication operation. If such an event occurs, the scan does not detect the deleted file and during replication the CSS may keep retrying the file until another scan occurs or the file becomes available.
To specify how the CSS handles file errors during content replication, use the replication file-error command. The syntax of this global configuration mode command is:
replication file-error retry|skip
The command options are :
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For example:
(config)# replication file-error skipDisplaying Content
The show content command enables you to display content entries in the Content Service Database (CSD) of a CSS. This command is available in all modes.
The syntax is:
show content slot slot_number {start-index index_number}
The variables and option are:
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For example, to look at the content from the module in chassis slot 2, starting at index 150, enter:
(config)# show content slot 2 start-index 150Table 14-5 describes the fields in the show content output.
