Table Of Contents
Configuring a CSS as a Content Routing Agent
Overview of the CRA Feature
CRA Quick Start
Configuring CRA Parameters
Enabling the CRA
Configuring the CPU Load Threshold
Configuring CRA Domain Records
Configuring an Alias for an Existing Client Domain
Clearing Domain Statistics
Displaying CRA Statistics
Configuring a CSS as a Content Routing Agent
This chapter provides an overview of the CSS Content Routing Agent (CRA) feature and describes how to configure it for operation. Information in this chapter applies to all CSS models, except where noted.
This chapter provides the following major sections:
•
Overview of the CRA Feature
•CRA Quick Start
•Configuring CRA Parameters
•Displaying CRA Statistics
Overview of the CRA Feature
To improve a client's overall browser experience by decreasing the response times for content requests, configure a CSS as a Content Routing Agent (CRA). A Cisco Content Router 4430-B (Content Router) running software version 1.1 redirects a client to the closest (best) replicated-content site represented by a CRA, based on network delay using a software process called boomerang. For details on the Cisco Content Router software and boomerang, refer to the Cisco Content Routing Software Configuration Guide and Command Reference, Release 1.1.
Configure a CRA at each content site within each domain that you want to support. This configuration also requires a Content Router.
The Content Router intercepts DNS requests from a client, then routes them to a CRA. For example, to route www.foo.com, the address record (A-record) in the primary DNS server for www.foo.com is changed to a name server record (NS-record) pointing to the Content Router. The Content Router and its CRAs handle all requests for the IP address of www.foo.com. When the CRAs receive a DNS request from the Content Router, the CRAs respond to the client's local name server at the same time. The first response through the network is used and the local name server discards all other responses. The CRA with the winning response is the site to which the client connects.
Figure 3-1 shows an example of the boomerang process in direct mode. A CSS configured as a CRA also works with a Content Router operating in (WCCP) mode. For more information on Content Router modes, refer to the Cisco Content Routing Software Configuration Guide and Command Reference, Release 1.1.
Note The Content Routing Agent feature is part of the CSS Standard feature set.
Figure 3-1 Example of Boomerang Content Routing Process - Direct Mode
CRA Quick Start
Table 3-1 provides a quick overview of the steps required to configure the Content Routing Agent feature on a CSS. 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 the table.
Table 3-1 Content Routing Agent Configuration Quick Start
Task and Command Example
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1. Configure a Cisco Content Router 4430-B. Configure Content Routing Agents (CRAs) and the domains associated with them on the Content Router. For details, refer to the Cisco Content Routing Software Configuration Guide and Command Reference, Release 1.1.
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2. On a CSS that you want to configure as a CRA, enter config mode.
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3. Enable the CRA feature on a CSS.
(config)# dns-boomerang client enable
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4. Create a domain record in the CRA for each domain with which you associated the CRA when you configured the Content Router.
(config)# dns-boomerang client domain www.sample.com 192.168.11.3
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5. (Optional) Configure an alias for each configured domain to reduce administrative overhead.
(config)# dns-boomerang client domain www.sample.com alias
gif.www.sample.com
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6. Display CRA statistics.
(config)# show dns-boomerang client
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The following running-config example shows the results of entering the commands described in Table 3-1.
!*************************** GLOBAL ***************************
dns-boomerang client enable
dns-boomerang client domain www.sample.com 192.168.11.3
dns-boomerang client domain www.sample.com alias gif.www.sample.com
Configuring CRA Parameters
The following sections describe the CLI commands and their options and variables that you use to configure the CSS as a CRA.
Enabling the CRA
To enable the CRA functionality on the CSS, use the dns-boomerang client enable command. There are no options for this global configuration mode command.
For example:
(config)# dns-boomerang client enable
To disable the CRA, enter:
(config)# no dns-boomerang client enable
Configuring the CPU Load Threshold
To set the CSS CPU load threshold for domains configured to use or return a local virtual IP address (VIP), use the dns-boomerang client cpu-threshold command. If the CPU load exceeds the configured threshold value, then the CSS drops subsequent incoming DNS requests from the Content Router until the load is lower than the threshold.
The syntax for this global configuration mode command is:
dns-boomerang client cpu-threshold number
The number variable specifies the load threshold value. Enter an integer from 1 to 99. The default is 99.
For example:
(config)# dns-boomerang client cpu-threshold 50
To reset the CSS CPU threshold to the default value, enter:
(config)# no dns-boomerang client cpu-threshold
Note To display the CPU load, use the show system-resources command.
Configuring CRA Domain Records
To create a domain record in the Content Routing Agent DNS server for each of the domains you associated the agent with when you configured domains on the Content Router, use the dns-boomerang client domain command. If the matching domain record keepalive messaging succeeds, the CSS uses this record for DNS resolutions. There is no Content Routing Agent configuration mode. Unlike other dns-record commands on the CSS, this command requires keywords for specifying options. (For details on configuring DNS domain records for other DNS applications, see the "Configuring Domain Records" section in Chapter 1, Configuring the CSS as a Domain Name System Server.)
The syntax for this global configuration mode command is:
dns-boomerang client domain dns_name ip_or_host {"uri"} {key
["secret"|des-encrypted encrypted_key|"encrypt_key"]}
{dns-ttl number1} {ip-ttl number2} {threshold number3}]
The variables and options for this command are:
•dns_name - The domain name mapped to the client record. Enter the name as a case-sensitive, unquoted text string with no spaces and a maximum length of 72 characters. For example, www.sample.com.
•ip_or_host - The IP address or the host name of the content server or web cache bound to the domain name on the CSS. This IP address can be a local VIP. Enter the address in dotted-decimal notation (for example, 192.168.11.3).
•"uri" - The optional URI that the CSS uses for the keepalive probe to the Content Router for a domain. Enter a quoted text string with a maximum of 255 characters. If you do not prepend the URI with a slash (/) character, the CSS prepends it.
•key - The optional keyword that defines the clear-text shared RC4 secret or DES encryption key on the Content Router. See Table 3-2 for a comparison of how you configure a password on a CSS (configured as a CRA) and on a Content Router.
•"secret" - The optional clear-text Content Router secret for encrypting packets sent between a Content Router and a CRA. The secret you specify here must match the secret configured on the Content Router. Enter the secret as a case-sensitive quoted text string with no spaces and a maximum of 64 characters (not including the quotes). For example, if MySecret is the secret configured on the Content Router for this domain, then enter "MySecret".
•des-encrypted - The optional keyword that specifies that a Data Encryption Standard (DES)-encrypted password follows.
•encrypted_key - The DES encryption key that the CSS had previously encrypted. The CSS does not re-encrypt this key and saves it in the running-config as you entered it. Enter an unquoted case-sensitive text string with no spaces and a maximum of 64 characters.
•"encrypt_key" - The DES encryption key that you want the CSS to encrypt. The CSS saves the encrypted key in the running-config as you entered it. Enter a quoted case-sensitive text string with no spaces and a maximum of 16 characters.
Table 3-2 Configuring a Password on a CSS (CRA) Versus a Content Router
CSS Password Command
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Content Router Password Command
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key "secret"
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no equivalent
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key des-encrypt "password"
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key word or key 0 word
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key des-encrypt password
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key 7 word
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Note The DES encryption algorithm on the CSS is different from the Cisco Type 7 encryption algorithm on the Content Router. Therefore, encrypted passwords are displayed differently on the CSS and on the CR.
•dns-ttl number - The optional DNS time-to-live keyword and value in seconds returned in the CRA's DNS responses. This option determines the length of time a DNS server caches the returned information for reuse. Enter an integer from 10 to 2147483647 seconds for a CSS. The default is the dns-ttl value configured on the Content Router.
•ip-ttl number - The optional IP routing time-to-live keyword and value in router hops returned in the CRA's DNS responses. This option determines how many router hops a response packet traverses enroute to the D-Proxy before it is discarded. This helps to eliminate the CRA from longer response routes. Enter an integer from 1 to 255. The default is the ip-ttl value configured on the Content Router.
•threshold number - The optional load threshold for testing the keepalive state of a local VIP. If the load on the dns-record associated with the content rule is greater than the threshold value, then the CSS drops subsequent Content Router requests for that record until the load is lower than the threshold. Enter an integer from 2 to 254. The default value is 254.
Note You must also configure the add dns command in the VIP's content rule to add domain names. Refer to the Cisco Content Services Switch Global Server Load-Balancing Configuration Guide.
For example:
(config)# dns-boomerang client domain www.foo.com 192.168.11.1 key
"MySecret" dns-ttl 240 ip-ttl 5 threshold 175
To remove a CRA domain, enter:
(config)# no dns-boomerang client domain www.foo.com
Configuring an Alias for an Existing Client Domain
You can create an alias for each configured client domain. An alias reduces administrative overhead by allowing you to use the shorter alias name instead of the domain name, IP address, and all the other options and variables associated with the configured record. The alias behaves exactly the same as the configured domain name.
To create an alias for an existing client domain, use the dns-boomerang client domain alias command. The syntax for this global configuration mode command is:
dns-boomerang client domain dns_name alias alias_name
The variables and options are:
•dns_name - The domain name of a configured client record. Enter the name as a case-sensitive, unquoted text string with no spaces and a maximum of 72 characters.
•alias - The keyword required to create an alias name.
•alias_name - The domain name that the CSS treats exactly the same as the associated dns_name. Enter the name as a case-sensitive, unquoted text string with no spaces and a maximum of 72 characters.
For example:
(config)# dns-boomerang client domain www.sample.com alias
gif.www.sample.com
To remove the alias, enter:
(config)# no dns-boomerang client domain alias www.sample.com
Clearing Domain Statistics
To clear the statistics for one or all configured domains, use the dns-boomerang client zero command. If you do not specify a domain name, the CSS clears the statistics for all configured domains. This command is available in SuperUser and all configuration modes.
The syntax for this global configuration mode command is:
dns-boomerang client zero dns-name
The variable for this command is dns_name, the domain name mapped to the client record statistics that you want to clear. Enter the name as a case-sensitive, unquoted text string with no spaces and a maximum of 72 characters.
For example:
(config)# dns-boomerang client zero www.sample.com
Displaying CRA Statistics
To display information for all configured CRA domains, use the show dns-boomerang client command. This command is available in SuperUser and all configuration modes.
The syntax for this global configuration mode command is:
show dns-boomerang client {all|global|domain {domain_name}}
The options and variable for this global configuration mode command are:
•all - Displays all information (global and domain-related) for all domains mapped to a client record. Same as the show dns-boomerang client command.
•global - Displays global information only for all domains mapped to a client record.
•domain - Displays domain-related information for all domains mapped to a client record.
•domain_name - Displays domain-related information for the specified domain.
For example:
(config)# show dns-boomerang client global
Table 3-3 describes the fields in the show dns-boomerang client output.
Table 3-3 Field Descriptions for the show dns-boomerang
client Command
Field
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Description
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Total DNS A-record requests
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The total number of address record requests from the Content Server.
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Total packets dropped
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Unknown domain
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The number of DNS packets with domains not configured on this CSS (for Content Routing).
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Invalid source address
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The number of packets with invalid source addresses.
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Excess length
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The number of packets that had lengths longer than what the CR could send.
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CPU threshold exceeded
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The number of packets dropped because the CPU threshold was exceeded.
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Configured CPU threshold
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The configured threshold value above which the CSS drops requests from the Content Router.
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Rule load threshold exceeded
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The number of requests from the Content Router that were dropped because the load on a local rule exceeded the configured threshold.
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Keepalive state Down
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The number of packets dropped because the keepalive failed.
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Security failure
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The number of requests for this domain that were dropped due to security errors (key/secret failure or mismatch).
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Domain
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The DNS name mapped to the client record.
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Content server
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The address of the content server bound to the domain.
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Origin server
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The address for the most recently used origin server that was passed from the Content Router.
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Bad probes
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The number of times (in percent) that the keepalive message failed to find the service Up.
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DNS A-record requests
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The number of DNS address record requests for this domain from the Content Router.
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Dropped (server down)
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The number of requests for this domain that were dropped because the server was down.
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Dropped (CPU busy)
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The number of requests for this domain that were dropped because the CPU threshold was exceeded.
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Dropped (rule load exceeded)
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The number of requests from the Content Router that were dropped because the load on a local rule exceeded the configured threshold.
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Configured threshold
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The load threshold value you configured with the dns-boomerang client domain command to test the keepalive state of a local VIP.
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Security failures
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The number of requests for this domain that were dropped due to security errors (key/secret failure or mismatch).
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Alias
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The alias that maps to the configured domain name.
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DNS A-record requests
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The number of DNS address record requests for this alias from the Content Router.
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