Cisco IOS Software Releases 12.1 E

Table Of Contents

DFP Agent Subsystem

Feature Overview

Benefits

Restrictions

Related Features and Technologies

Related Documents

Supported Platforms

Supported Standards, MIBs, and RFCs

Prerequisites

Configuration Tasks

Monitoring and Maintaining the DFP Agent Subsystem Feature

Configuration Examples

Command Reference

debug ip dfp agent

inservice (DFP agent)

interval (DFP agent)

ip dfp agent

manager

password

port (DFP agent)

show ip dfp

Glossary

DFP Agent Subsystem

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Feature History

Release	Modification
12.1(8a)E	This feature was introduced.

This document describes the Dynamic Feedback Protocol (DFP) Agent Subsystem feature in Cisco IOS Release 12.1(8a)E. It includes the following sections:

•Feature Overview

•Supported Platforms

•Supported Standards, MIBs, and RFCs

•Prerequisites

•Configuration Tasks

•Monitoring and Maintaining the DFP Agent Subsystem Feature

•Configuration Examples

•Command Reference

•Glossary

Feature Overview

The Dynamic Feedback Protocol (DFP) enables a DFP agent in a local load-balancing environment to collect status information from one or more real host servers, convert the information to relative weights, and report the weights to a DFP manager, such as an IOS Server Load Balancing (SLB) device. The DFP manager factors in the weights when load balancing the real servers. DFP also supports global load-balancing environments, with IOS SLB reporting weights to DistributedDirector. For more information about DFP, see the IOS Server Load Balancing feature module.

Prior to 12.1(8a)E, the DFP agent was implemented only in IOS SLB. The new DFP agent subsystem feature enables client subsystems other than IOS SLB to act as DFP agents. However, currently IOS SLB is the only supported subsystem. You can use multiple DFP agents from different client subsystems at the same time.

The DFP Agent Subsystem is bundled with the IOS SLB and GGSN products, it is not available separately.

Benefits

The DFP agent subsystem enables client subsystems other than IOS SLB to act as DFP agents, sending weights to a DFP manager.

Restrictions

The DFP agent subsystem has the following restrictions:

•The DFP agent requires a delay between hello messages of at least 3 seconds. Therefore, if your DFP manager provides a timeout specification, you must set the timeout to at least 3 seconds.

•The password specified in the DFP manager must match the password specified on the password command in the DFP agent.

•As part of the implementation of the DFP agent subsystem, the manager command has been removed. Its function is now provided by the ip dfp agent global configuration command, and by the following DFP agent configuration commands:

–inservice (DFP agent)

–interval (DFP agent)

–password

–port (DFP agent)

Related Features and Technologies

•IOS Server Load Balancing (IOS SLB)

•Dynamic Feedback Protocol (DFP)

Related Documents

•Cisco IOS IP Configuration Guide, Release 12.2

•Cisco IOS IP Command Reference, Volume 1 of 3: Addressing and Services, Release 12.2

•Dynamic Feedback Protocol Support in Distributed Director

•IOS Server Load Balancing feature module

Supported Platforms

•Catalyst 6000 Family Switches

•Cisco 7100 Series Routers

•Cisco 7200 Series Routers

Supported Standards, MIBs, and RFCs

Standards

•No new or modified standards

MIBs

•No new or modified MIBs

RFCs

•No new or modified RFCs

Prerequisites

The DFP agent subsystem has no prerequisites.

Configuration Tasks

To define the port number to be used by the DFP manager to connect to the IOS SLB DFP agent to receive DFP reports, enter the following commands in order, beginning in global configuration mode:

	Command	Description
Step 1	Router(config)# ip dfp agent subsystem-name	Identifies a DFP agent subsystem and initiates DFP agent configuration mode. See the ip dfp agent command for more details.
Step 2	Router(config-dfp)# interval seconds	(Optional) Configures a DFP agent weight recalculation interval. See the interval (DFP agent) command for more details.
Step 3	Router(config-dfp)# password [0|7] password [timeout]	(Optional) Configures a DFP agent password for MD5 authentication. See the password command for more details.
Step 4	Router(config-dfp)# port port-number	Defines the port number to be used by the DFP manager to connect to the DFP agent. See the port (DFP agent) command for more details.
Step 5	Router(config-dfp)# inservice	Enables the DFP agent for communication with a DFP manager. A DFP agent is inactive until both of the following conditions are met: •The DFP agent has been enabled using the inservice (DFP agent) command. •The client subsystem has changed the DFP agent's state to ACTIVE. See the inservice (DFP agent) command for more details.

Monitoring and Maintaining the DFP Agent Subsystem Feature

To obtain and display runtime information about the DFP agent subsystem, use the following commands in EXEC mode:

Command	Purpose
Router# show ip dfp [agent subsystem_name] [detail]	Displays information about DFP agents. See the show ip dfp command for more details.
Router# show ip slb dfp [agent agent_ip_address port-number | manager manager_ip_address | detail | weights]	Displays information about DFP and DFP agents, and about the weights assigned to real servers. See the show ip slb dfp command in the Cisco IOS IP Command Reference, Volume 1 of 3: Addressing and Services, Release 12.2 for more details.

Configuration Examples

The following example shows the commands used to configure the DFP agent subsystem. Use these commands to accomplish the following tasks:

•Identify DFP agent subsystem slb and change the CLI to DFP agent configuration mode.

•Set the DFP agent weight recalculation interval to 11 seconds.

•Set the unencrypted DFP agent password to Cookies (to match the DFP manager's password) and the timeout to 180 seconds.

•Set the DFP communication port number for to 2221.

•Enable the DFP agent for communication with the DFP manager.

Router(config)# ip dfp agent slb

Router(config-dfp)# interval 11

Router(config-dfp)# password Cookies 180

Router(config-dfp)# port 2221

Router(config-dfp)# inservice

Command Reference

This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.2 command reference publications.

•debug ip dfp agent

•inservice (DFP agent)

•interval (DFP agent)

•ip dfp agent

•manager

•password

•port (DFP agent)

•show ip dfp

debug ip dfp agent

To display debug messages for the DFP agent subsystem, use the debug ip dfp EXEC command. To stop debug output, use the no form of this command.

debug ip dfp agent

no debug ip dfp agent

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values.

Command Modes

EXEC configuration

Command History

Release	Modification
12.1(8a)E	This command was introduced.

Usage Guidelines

See the following caution before using debug commands:

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Caution Because debugging output is assigned high priority in the CPU process, it can render the system unusable. For this reason, use debug commands only to troubleshoot specific problems or during troubleshooting sessions with Cisco technical support staff. Moreover, it is best to use debug commands during periods of lower network flows and fewer users. Debugging during these periods reduces the effect these commands have on other users on the system.

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This command displays debug messages for the DFP agent subsystem.

Examples

The following example configures a DFP agent debug session:

Router# debug ip dfp agent

DFP debugging is on

Router#

The following example stops all debugging:

Router# no debug all

All possible debugging has been turned off

Router#

inservice (DFP agent)

To enable the DFP agent for communication with a DFP manager, use the inservice DFP agent configuration command. To remove the DFP agent from service, use the no form of this command.

inservice

no inservice

Syntax Description

This command has no arguments or keywords.

Defaults

If the inservice command is not specified, the DFP agent is inactive.

Command Modes

DFP agent configuration

Command History

Release	Modification
12.1(8a)E	This command was introduced.

Usage Guidelines

A DFP agent is inactive until both of the following conditions are met:

•The DFP agent has been enabled using the inservice (DFP agent) command.

•The client subsystem has changed the DFP agent's state to ACTIVE.

When you use the no form of this command to remove a DFP agent from service, the DFP agent closes all open connections, and no new connections are assigned.

Examples

In the following example, the DFP agent is enabled for communication with a DFP manager:

Router(config)# ip dfp agent slb

Router(config-dfp)# inservice

Related Commands

Command	Description
agent	Identifies a DFP agent to which IOS SLB can connect.
ip dfp agent	Identifies a DFP agent subsystem and initiates DFP agent configuration mode.
ip slb dfp	Configures DFP, supplies an optional password, and initiates DFP configuration mode.

interval (DFP agent)

To configure a DFP agent weight recalculation interval, use the interval DFP agent configuration command. To restore the default setting, use the no form of this command.

interval seconds

no interval seconds

Syntax Description

seconds

Specifies the number of seconds to wait before recalculating weights for the DFP manager. Valid values range from 5 to 65535 seconds. The default interval is 10 seconds.

Defaults

The default interval value is 10 seconds.

Command Modes

DFP agent configuration

Command History

Release	Modification
12.1(8a)E	This command was introduced.

Usage Guidelines

The DFP agent sends the new weight to the DFP manager only if the new weight is different from the old weight. If the new weight is the same as the old weight, it is not sent to the DFP manager.

Examples

The following example configures the DFP agent to recalculate weights every 11 seconds:

Router(config)# ip dfp agent slb

Router(config-dfp)# interval 11

Related Commands

Command	Description
agent	Identifies a DFP agent to which IOS SLB can connect.
ip dfp agent	Identifies a DFP agent subsystem and initiates DFP agent configuration mode.
ip slb dfp	Configures DFP, supplies an optional password, and initiates DFP configuration mode.

ip dfp agent

To identify a DFP agent subsystem and initiate DFP agent configuration mode, use the ip dfp agent global configuration command. To remove the DFP agent identification, use the no form of this command.

ip dfp agent subsystem-name

no ip dfp agent subsystem-name

Syntax Description

subsystem-name

Character string used to identify the DFP agent subsystem, such as slb for IOS SLB. The subsystem name enables the subsystem to send weights to a DFP manager. The subsystem name is limited to 15 characters.

Defaults

No default behavior or values.

Command Modes

Global configuration

Command History

Release	Modification
12.1(8a)E	This command was introduced.

Usage Guidelines

To discover the subsystem names that are available in your environment, enter the following command:

ip dfp agent ?

Examples

The following example identifies a DFP agent subsystem named slb:

Router(config)# ip dfp agent slb

Router(config-dfp)#?

Related Commands

Command	Description
agent	Identifies a DFP agent to which IOS SLB can connect.
ip slb dfp	Configures DFP, supplies an optional password, and initiates DFP configuration mode.

manager

This command has been removed. Its function is now performed by the ip dfp agent global configuration command, and by the following DFP agent configuration commands:

•inservice (DFP agent)

•interval (DFP agent)

•password

•port (DFP agent)

password

To configure a DFP agent password for MD5 authentication, use the password DFP agent configuration command. To remove the DFP agent password, use the no form of this command.

password [0|7] password [timeout]

no password

Syntax Description

0	(Optional) Specifies that the password is unencrypted. This is the default setting.
7	(Optional) Specifies that the password is encrypted.
password	(Optional) Password value for MD5 authentication. This password must match the password configured on the host agent.
timeout	(Optional) Delay period, in seconds, during which both the old password and the new password are accepted. The valid range is 0 to 65535 seconds. The default value is 180 seconds.

Defaults

The password encryption default is 0 (unencrypted).

The password timeout default is 180 seconds.

Command Modes

DFP agent configuration

Command History

Release	Modification
12.1(8a)E	This command was introduced.

Usage Guidelines

The password specified on this command must match the password specified on the DFP manager.

The timeout option allows you to change the password without stopping messages between the DFP agent and its manager. The default value is 180 seconds.

During the timeout, the agent sends packets with the old password (or null, if there is no old password), and receives packets with either the old or new password. After the timeout expires, the agent sends and receives packets only with the new password; received packets that use the old password are discarded.

If you are changing the password for an entire load-balanced environment, set a longer timeout. This allows enough time for you to update the password on all agents and servers before the timeout expires. It also prevents mismatches between agents and servers that have begun running the new password and agents, and servers on which you have not yet changed the old password.

Examples

The following example sets the DFP agent password (unencrypted by default) to Cookies and the timeout to 360 seconds:

Router(config)# ip dfp agent slb

Router(config-dfp)# password Cookies 360

Related Commands

Command	Description
agent	Identifies a DFP agent to which IOS SLB can connect.
ip dfp agent	Identifies a DFP agent subsystem and initiates DFP agent configuration mode.
ip slb dfp	Configures DFP, supplies an optional password, and initiates DFP configuration mode.
replicate casa (firewall farm)	Configures a stateful backup of IOS SLB decision tables to a backup switch.
replicate casa (virtual server)	Configures a stateful backup of IOS SLB decision tables to a backup switch.

port (DFP agent)

To define the port number to be used by the DFP manager to connect to the DFP agent, use the port (DFP agent) DFP agent configuration command. To disable the port number definition and remove existing connections, use the no form of this command.

port port-number

no port port-number

Syntax Description

port-number

Port number used by the DFP manager to connect to the DFP agent. The valid range is 1 to 65535.

Defaults

No default behavior or values.

Command Modes

DFP agent configuration

Command History

Release	Modification
12.1(8a)E	This command was introduced.

Examples

In the following example, the DFP manager is enabled to connect to the DFP agent using port number 2221:

Router(config)# ip dfp agent slb

Router(config-dfp)# port 2221

Related Commands

Command	Description
agent	Identifies a DFP agent to which IOS SLB can connect.
ip dfp agent	Identifies a DFP agent subsystem and initiates DFP agent configuration mode.
ip slb dfp	Configures DFP, supplies an optional password, and initiates DFP configuration mode.

show ip dfp

To display information about DFP agents, use the show ip dfp privileged EXEC command.

show ip dfp [agent subsystem-name] [detail]

Syntax Description

agent subsystem-name	(Optional) Displays information about the specified DFP agent, such as slb for IOS SLB.
detail	(Optional) Displays detailed DFP agent information.

Defaults

If no options are specified, the command displays output for all DFP agents identified by ip dfp agent commands, regardless of whether those agents are currently in service (Inservice: yes) or active (AppActive: yes).

Command Modes

Privileged EXEC

Command History

Release	Modification
12.1(8a)E	This command was introduced.

Usage Guidelines

Detailed output for show ip dfp includes information about all DFP agents identified by ip slb agent commands, regardless of whether those agents are currently in service (Inservice: yes) or active (AppActive: yes).

Examples

The following example shows detailed information for DFP agent slb:

Router# show ip dfp agent slb detail

Unexpected errors: 0

DFP Agent for service: SLB

      Port: 666 Interval: 10

      Current passwd: <none> Pending passwd: <none>

      Passwd timeout: 0

      Inservice: yes  AppActive: yes

      Manager IP Address   Timeout

      ------------------   -------

      172.18.45.27         0

Weight Table Report for Agent SLB

      Weights for Port: 80  Protocol: TCP

          IP Address        Bind ID  Weight

          ---------------   -------  -------

          1.1.1.1           0        65535

      Weights for Port: 0 (wildcard)  Protocol: 0 (wildcard)

          IP Address        Bind ID  Weight

          ---------------   -------  -------

          0.0.0.0           65534    0

Bind ID Table Report for Agent SLB

      Bind IDs for Port: 80  Protocol: TCP

          Bind ID   Client IP        Client Mask

          -------   ---------------  ---------------

          0         0.0.0.0          0.0.0.0

Table 1 show ip dfp Field Descriptions 

Field	Description
Port	TCP port number of the agent.
Interval	Number of seconds to wait before recalculating weights.
Current passwd	Current DFP password for MD5 authentication.
Pending passwd	Pending new DFP password for MD5 authentication.
Passwd timeout	Delay period, in seconds, during which both the current password and the new password are accepted.
Inservice	Indicates whether the DFP agent is enabled for communication with a DFP manager.
AppActive	Indicates whether the DFP agent is active.
Manager IP Address	IP address of the manager to which weights are being sent.
Timeout	Time period, in seconds, during which the DFP manager must receive an update from the DFP agent. A value of 0 means there is no timeout.
Weights for Port	Port for which the following weights are reported. 0 indicates a wildcard value.
Protocol	Protocol used for the port. 0 indicates a wildcard value.
IP Address	IP address for which weight is reported.
Bind ID	Bind ID associated with the IP address.
Weight	Weight calculated for the IP address.
Bind IDs for Port	Port for which the following bind IDs are reported.
Protocol	Protocol used for the port.
Bind ID	Bind ID of this instance of the real server.
Client IP	IP address of client using the virtual server.
Client Mask	IP network mask of client using the virtual server.

Related Commands

Command	Description
agent	Identifies a DFP agent to which IOS SLB can connect.
ip dfp agent	Identifies a DFP agent subsystem and initiates DFP agent configuration mode.
ip slb dfp	Configures DFP, supplies an optional password, and initiates DFP configuration mode.

Glossary

client subsystem—Users, such as IOS SLB, of the DFP agent function.

DFP—Dynamic Feedback Protocol. Allows host agents to dynamically report the change in status of the host systems providing a virtual service. The status reported is a relative weight that specifies a host server's capacity to perform work.

DFP agent—Object in a load-balanced environment that dynamically reports changes in status of the host systems that provide a virtual service. The status reported is a relative weight that specifies a host server's capacity to perform work. See also DFP manager.

DFP manager—Object in a load-balanced environment that collects status reports from DFP agents. See also DFP agent.

Dynamic Feedback Protocol—See DFP.

IOS SLB—IOS Server Load Balancing. Load-balancing function in which the network administrator defines a virtual server that represents a group of real servers in a cluster of network servers known as a server farm. When a client initiates a connection to the virtual server, IOS SLB chooses a real server for the connection based on a configured load-balancing algorithm.

Server Load Balancing—See IOS SLB.

services manager—Functionality built into IOS SLB that makes load-balancing decisions based on application availability, server capacity, and load distribution algorithms such as weighted round robin or weighted least connections, or the DFP. The services manager determines a real server for the packet flow using load balancing and server/application feedback.

SLB—See IOS SLB.