This documentation has been moved
DistributedDirector Enhancements for Cisco IOS Release 12.1(5)T
Downloads: This chapterpdf (PDF - 131.0KB) The complete bookPDF (PDF - 3.01MB) | Feedback

DistributedDirector Enhancements for Cisco IOS Release 12.1(5)T

Table Of Contents

DistributedDirector Enhancements for Cisco IOS Release 12.1(5)T

Feature Overview

Benefits

Restrictions

Related Documents

Finding Feature Information

Supported Standards, MIBs, and RFCs

Configuration Tasks

Configuring Enhanced Fault Tolerance with Multiple Resource Records

Configuring Event Recording with Syslog

Configuring Enhanced Server Verification with Multiple Port Connect Tests

Verifying Enhanced Fault Tolerance with Multiple Resource Records

Verifying Event Recording with Syslog

Verifying Enhanced Server Verification with Multiple Port Connect Tests

Configuration Examples

Enhanced Fault Tolerance with Multiple Resource Records Example

Event Recording with Syslog Example

Enhanced Server Verification with Multiple Port Connect Tests Example


DistributedDirector Enhancements for Cisco IOS Release 12.1(5)T



Note Effective with Cisco IOS Release 12.4(24)T, this feature is not available in Cisco IOS software.


This feature module describes the DistributedDirector Enhancements for Cisco IOS Release 12.1(5)T feature and includes the following sections:

Feature Overview

Finding Feature Information

Supported Standards, MIBs, and RFCs

Configuration Tasks

Configuration Examples

Command Reference, page 6

Feature Overview

The DistributedDirector Enhancements for Cisco IOS Release 12.1(5)T feature consists of the following modified features for the DistributedDirector, which were introduced in Cisco IOS Release 11.1(28)IA:

Enhanced Fault Tolerance with Multiple Resource Records

Event Recording with Syslog

Enhanced Server Verification with Multiple Port Connect Tests

The DistributedDirector Enhancements for Cisco IOS Release 12.1(5)T feature also consists of several unrelated new commands. These commands can be found in the Command Reference section.

Enhanced Fault Tolerance with Multiple Resource Records

Before this enhancement, DistributedDirector would return a single Resource Record (RR) in each Domain Name System (DNS) response. A single RR is normally sufficient, but for some applications, server failover will occur more rapidly when applications are provided IP addresses of multiple servers.

The Enhanced Fault Tolerance with Multiple Resource Records feature enables DistributedDirector to return multiple RRs. The number of RRs returned in a single reply is configurable. The default number of RRs returned is one.

Event Recording with Syslog

The Event Recording with Syslog feature enables DistributedDirector to log events by way of the industry-standard syslog system. Server state is logged, providing a useful log of when servers are considered up or down. The logging priority level is notification with priority level five. Additionally, the server selection process, DNS request, and DNS response may be logged. The logging priority level is informational with priority level six.

Enhanced Server Verification with Multiple Port Connect Tests

Before this enhancement, DistributedDirector could evaluate server status by performing a TCP connect test to a single server port. The Enhanced Server Verification with Multiple Port Connect Tests feature allows multiple port connect tests to be specified. If any one of the connect tests fails, the server is considered down.

Benefits

The features provided in Cisco IOS Release 12.1(5)T help make networks that use DistributedDirector more robust. These features ensure that applications have more useful information and perform better server verification, and they allow administrators to track DistributedDirector better. In particular:

The Enhanced Fault Tolerance with Multiple Resource Records feature provides better fault tolerance for clients.

The Event Recording with Syslog feature provides the ability to examine DNS traffic and the way in which servers are chosen.

The Enhanced Server Verification with Multiple Port Connect Tests feature better reflects the reality that some services span several ports and require that all ports be up.

Restrictions

Enhanced Fault Tolerance with Multiple Resource Records

Configuring DistributedDirector to return a large number of records can reduce the benefit of using DistributedDirector to select the best server.

Event Recording with Syslog

Extensive syslog output is provided when logging server selection. Therefore, this feature should not be used when a heavy request load is expected.

Related Documents

For more information on the Cisco DistributedDirector, see the following documents, which are located on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml:

Cisco DistributedDirector 2500 Series Installation and Configuration Guide

Cisco DistributedDirector 4700-M Installation and Configuration Guide

Release Notes for Cisco DistributedDirector System Software

Cisco DistributedDirector Enhancements for Release 11.1(18)IA

Cisco DistributedDirector Enhancements for Release 11.1(25)IA

Cisco DistributedDirector Enhancements for Release 11.1(28)IA

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Supported Standards, MIBs, and RFCs

Standards

None

MIBs

None

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

None

Configuration Tasks

See the following sections for configuration tasks for this feature. Each task is optional.

Configuring Enhanced Fault Tolerance with Multiple Resource Records(Optional)

Configuring Event Recording with Syslog (Optional)

Configuring Enhanced Server Verification with Multiple Port Connect Tests (Optional)

Verifying Enhanced Fault Tolerance with Multiple Resource Records (Optional)

Verifying Event Recording with Syslog (Optional)

Verifying Enhanced Server Verification with Multiple Port Connect Tests (Optional)

Configuring Enhanced Fault Tolerance with Multiple Resource Records

To configure the Enhanced Fault Tolerance with Multiple Resource Records feature on the DistributedDirector for a host name, use the following command in global configuration mode:

Command
Purpose

Router(config)# ip director host host-name [a | mx] multiple integer

Configures the number of RRs that the DistributedDirector returns for each DNS response.

Configuring Event Recording with Syslog

To configure the Event Recording with Syslog feature on the DistributedDirector for a host name, use the following commands in global configuration mode:

Command
Purpose

Router(config)# logging host

Router(config)# logging trap informational

Router(config)# ip director host host-name [a | mx] logging

Configures the DistributedDirector to log events to syslog.

Configuring Enhanced Server Verification with Multiple Port Connect Tests

To configure the Enhanced Server Verification with Multiple Port Connect Tests feature on the DistributedDirector, use the following commands in global configuration mode:

Command
Purpose

Router(config)# ip director host host-name [a | mx] connect port-1 [interval] connection-interval n

Router(config)# ip director host host-name [a | mx] connect port-2 [interval] connection-interval n

Router(config)# ip director host host-name [a | mx] connect port-n [interval] connection-interval n

Enables the DistributedDirector to verify that a server is available.

When you configure multiple ip director host connect commands for the same host name but with different port numbers, the DistributedDirector verifies that all of the ports are accessible. If any of the ports is not accessible, the host is considered down.

Verifying Enhanced Fault Tolerance with Multiple Resource Records

To verify that the DistributedDirector is configured to return the best servers for RRs for each DNS, use the show ip director hosts command.

Verifying Event Recording with Syslog

To verify that the DistributedDirector is configured to send to syslog the DNS request and response information, use the show ip director hosts command.

Verifying Enhanced Server Verification with Multiple Port Connect Tests

To verify that the DistributedDirector is configured with a specific connection interval to specified distributed servers, use the show ip director hosts command.

Configuration Examples

This section provides the following configuration examples:

Enhanced Fault Tolerance with Multiple Resource Records Example

Event Recording with Syslog Example

Enhanced Server Verification with Multiple Port Connect Tests Example

Enhanced Fault Tolerance with Multiple Resource Records Example

In the following examples, the DistributedDirector is configured to return the best three servers for A resource record on host name www.xyz.com, the best two servers for A resource record on host name alias.xyz.com, and the best two servers for MX resource mail.xyz.com, respectively:

ip director host www.xyz.com multiple 3
ip director host alias.xyz.com a multiple 2
ip director host mail.xyz.com mx multiple 2

Event Recording with Syslog Example

Before configuring the DistributedDirector to syslog events regarding DNS requests on a specific resource record, the following must be typed on the command line:

logging 172.21.34.2
logging trap informational

Note The IP address specified above is the IP address of the log server in which the syslog messages get recorded.


In the following examples, the DistributedDirector is configured to syslog events regarding DNS requests on A resource record for host name www.xyz.com, DNS requests on A resource record for host name alias.xyz.com, and DNS requests on MX host name mail.xyz.com, respectively:

ip director host www.xyz.com logging
ip director host alias.xyz.com a logging
ip director host mail.xyz.com mx logging

Enhanced Server Verification with Multiple Port Connect Tests Example

In the following example, the DistributedDirector is configured with a connection interval of 5 minutes to distributed servers on port 80 and port 90. The distributed servers will only be considered accessible if both port 80 and port 90 are accessible:

ip director host www.xyz.com connect 80 5
ip director host www.xyz.com connect 90 5