Cisco IOS Software Releases 12.2 T

Table Of Contents

DistributedDirector Cache Auto Refresh

Feature Overview

Benefits

Related Technologies

Related Documents

Supported Platforms

Supported Standards, MIBs, and RFCs

Prerequisites

Configuration Tasks

Enabling Cache Auto Refresh

Verifying the Cache Auto Refresh Feature

Configuration Examples

Enabling the Cache Auto Refresh Feature Example

Command Reference

ip director cache refresh

DistributedDirector Cache Auto Refresh

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Feature History

Release	Modification
12.2(8)T	This feature was introduced.

This document describes the DistributedDirector Cache Auto Refresh feature in Cisco IOS Release 12.2(8)T. It includes the following sections:

•Feature Overview

•Supported Platforms

•Supported Standards, MIBs, and RFCs

•Prerequisites

•Configuration Tasks

•Configuration Examples

•Command Reference

Feature Overview

The DistributedDirector Cache Auto Refresh feature works in the background to continuously update all entries in the DistributedDirector cache. Once this background refresh feature is initiated, DistributedDirector periodically updates all expired cache entries. The DistributedDirector cache saves the latest answers to all past Domain Name System (DNS) queries received since cache auto refresh was initiated, and any repeat request is served directly from the cache when caching is enabled.

The new ip director cache refresh command enables the automatic background refresh feature for the DistributedDirector cache.

Benefits

Once the cache auto refresh feature is enabled, the cache will actively and continuously update every expired entry. This feature allows DistributedDirector to return answers to queries according to the latest and most accurate network information.

Related Technologies

DistributedDirector Configurable Cache

Related Documents

DistributedDirector Configurable Cache, Cisco IOS Release 12.2(8)T feature module

Supported Platforms

•Cisco 2600 series

•Cisco 3620 series

•Cisco 3640 series

•Cisco 3660 series

•Cisco 3725 series

•Cisco 3745 series

•Cisco 7200 series

Determining Platform Support Through Feature Navigator

Cisco IOS software is packaged in feature sets that support specific platforms. To get updated information regarding platform support for this feature, access Feature Navigator. Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.

Feature Navigator is a web-based tool that enables you to quickly determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image.

To access Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions at http://www.cisco.com/register.

Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Feature Navigator home page at the following URL:

http://www.cisco.com/go/fn

Supported Standards, MIBs, and RFCs

Standards

No new standards are supported by this feature.

MIBs

No new MIBs are supported by this feature.

To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL:

http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

RFCs

No new RFCs are supported by this feature.

Prerequisites

The sorting cache must be enabled on DistributedDirector. To enable the sorting cache, use the ip director cache command.

Configuration Tasks

See the following section for configuration tasks for cache auto refresh. Each task in the list is identified as either required or optional.

•Enabling Cache Auto Refresh (required)

Enabling Cache Auto Refresh

To enable cache auto refresh for DistributedDirector, use the ip director cache refresh command.

	Command	Purpose
Step 1	Router(config)# ip director cache	Enables the sorting cache on DistributedDirector.
Step 2	Router(config)# ip director cache refresh	Enables the DistributedDirector Cache Auto Refresh feature.

To turn off cache auto refresh, use the no ip director cache refresh command.

	Command	Purpose
Step 1	Router(config)# no ip director cache refresh	Disables the DistributedDirector Cache Auto Refresh feature.

Verifying the Cache Auto Refresh Feature

To verify that the DistributedDirector Cache Auto Refresh feature is configured, enter the show running-config command.

Router(config)# ip director cache 

Router(config)# ip director cache refresh

Router# show running-config

ip host myhost 172.2.2.10 172.2.2.20 172.2.2.30 

.

.

.

ip director cache refresh

Configuration Examples

This section provides the following configuration example:

•Enabling the Cache Auto Refresh Feature Example

Enabling the Cache Auto Refresh Feature Example

In the following example, the cache auto refresh background feature for DistributedDirector is enabled:

Router(config)# ip director cache 

Router(config)# ip director cache refresh

Router# show running-config

ip host myhost 172.2.2.10 172.2.2.20 172.2.2.30 

.

.

.

ip director cache refresh

Command Reference

This section documents new commands. All other commands used with this feature are documented in the Cisco IOS DistributedDirector command reference publications for various releases.

•ip director cache refresh

ip director cache refresh

To enable the DistributedDirector Cache Auto Refresh feature, use the ip director cache refresh command in global configuration mode. To disable automatic background refresh, use the no form of this command.

ip director cache refresh

no ip director cache refresh

Syntax Description

This command has no keywords or arguments.

Defaults

Automatic background refresh is disabled.

Command Modes

Global configuration

Command History

Release	Modification
12.2(8)T	This command was introduced.

Usage Guidelines

The sorting cache on DistributedDirector must be enabled before you can use the ip director cache refresh command. To enable the sorting cache, use the ip director cache command.

Once automatic background refresh for the DistributedDirector cache is enabled, the cache will actively and continuously update every expired entry by processing a fake Domain Name System (DNS) request. The cache accumulates and updates answers to all past DNS queries received since cache auto refresh was initiated. Any repeat DNS request is always serviced directly from the cache.

Examples

The following example enables automatic background refresh for the DistributedDirector cache:

Router(config)# ip director cache 

Router(config)# ip director cache refresh

Router# show running-config

ip host myhost 172.2.2.10 172.2.2.20 172.2.2.30 

.

.

.

ip director cache refresh