Configuring an ICAP 1.0 service farm

You must plan the configuration

ICAP service farm configuration will require less time if you make some decisions and gather some information before you start configuring the NetCache appliance.

To plan for the ICAP service farm configuration, you must do the following:

Obtain capacity planning information from the service vendor to ensure that your compute resources meet service requirements.
Configure the NetCache ICAP client and the ICAP server on the same network to ensure best performance.
Ensure that your ICAP server is appropriately configured with a third-party service, such as virus scanning.
Determine the appropriate vectoring point for the ICAP services you intend to support. For example, content filtering is REQMOD_PRECACHE. See Vectoring points for a description of vectors and their relationship to ICAP services.
Determine a load-balancing scheme: round robin, IP address, or least usage. See Load balancing for a description of load-balancing schemes for ICAP service farms.
Determine your ICAP service URL. Service farms can support various services, and each service is associated with a URL. The URL string identifies the service to NetCache and toggles the ICAP service on or off. For example:
icap:// IP address or hostname of the ICAP server : port / service name [on | off]

Note
The NetCache default port number for ICAP services is 1344.
Understand how to enable and apply ACLs for ICAP services. ACLs must be enabled, and rules to direct requests and control services are required. For example:
icap(virus_check, ad_insert) user bob

See Controlling access to ICAP services for information about handling requests for ICAP services.

Configuring ICAP using the CLI

To get information about ICAP 1.0 configuration options from the CLI, enter the following command:

set config.icapv1.?

The preceding command lists the available ICAP options.

To get help for a specific ICAP option, enter the following command:

help config.icapv1.optionname

Creating an ICAP service farm

Use the Appliance Manager to add or delete ICAP service farms. When service farms are added or removed, the service farm data structure is updated and reflected in the Appliance Manager. No reboot is necessary after an ICAP service farm is added or edited. When a host is deleted from the service farm list, the ICAP service is removed, all connections are shut down, and eventually cached items become stale and are reclaimed.

To create an ICAP service farm, complete the following steps.

Step	Action
1	In the Appliance Manager, select Setup tab > ICAP > ICAP 1.0.
2	Click the Service Farms tab, then click New Service Farm.
3	Enter the ICAP service farm name.
4	Select the vectoring point within the ICAP pipeline where ICAP services are invoked: REQMOD_PRECACHE modifies a request before it is sent to the cache. REQMOD_POSTCACHE modifies a request before it is sent to the origin server. RESPMOD_PRECACHE modifies objects sent from an origin server on the way to the cache.
5	Specify the order in which the service is listed. New farms are added to the end of the list of ICAP services.
6	Select the Service Farm Enable check box to enable the service farm.
7	In the Load Balancing option, select a load-balancing scheme: Round robin uses a one-to-one rotation among service farms. IP-address-based uses IP address hashing to ensure that the same clients fetch through the same ICAP service. Least usage selects a host based on a combination of service capability and the number of outstanding connections.
8	Select the Bypass on Failure check box if you want to bypass the service farm when an ICAP server is unavailable.
9	Specify the consistency or service availability within an ICAP service farm if you are running more than one version of a service. Weak specifies a service farm that runs more than one version of a service. Weak is the preferred consistency setting because content is not checked for inconsistent results. Strong specifies a service farm that should not be configured to run more than one version of a service. Strong deactivates service versions that are not consistent with the majority. lbw (load balanced weak) specifies a service farm configuration that is compromised if the number of servers is reduced. lbw toggles to Weak if servers become overloaded.
10	Specify the lbw threshold as a value between 0 and 1. This value is required only if lbw is specified as a consistency setting. This is the number of ICAP services that can operate at greater than peak server load.
11	In the Services option, specify the ICAP service URLs. Use the following format: icap:// IP address or hostname of the ICAP server : port / service_name [on \| off] where IP address or hostname specifies the service, port specifies the default ICAP port, and service_name (optional) specifies the name of a service. Enable or disable the service by specifying "on" or "off" at the end of the URL string. Note The NetCache default port number for ICAP services is 1344.
12	Click Commit Changes at the bottom of the page.

Editing a service farm

To edit an existing service farm, complete the following steps.

Step	Action
1	In the Appliance Manager, select Setup tab > ICAP > ICAP 1.0.
2	Click the Service Farms tab.
3	Select or clear the Enable check box for a specific service farm to enable or disable it.
4	Select or clear the Del check box for a specific service farm to delete or retain it.
5	To edit a service farm, click Edit for the service farm you want to edit.
6	Change any options on the Edit ICAP Service Farm page, as required. For more information about the various options, see Creating an ICAP service farm.
7	Click Commit Changes at the bottom of the page.