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Table Of Contents
Restrictions for the DFP Agent Subsystem
Information About the DFP Agent Subsystem
How to Configure the DFP Agent Subsystem
Displaying Information About DFP Agents
Displaying Information About DFP and DFP Agents
Configuration Examples for the DFP Agent Subsystem
Obsolete and Replaced Commands
DFP Agent Subsystem
This document describes the Dynamic Feedback Protocol (DFP) agent subsystem feature in Cisco IOS Release 12.2(14)S. The DFP agent subsystem enables client subsystems other than IOS Server Load Balancing (SLB) to act as DFP agents, sending weights to a DFP manager.
Feature Specifications for the DFP Agent Subsystem Feature
Determining Platform Support Through Cisco Feature Navigator
Cisco IOS software is packaged in feature sets that are supported on specific platforms. To get updated information regarding platform support for this feature, access Cisco Feature Navigator. Cisco Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.
Cisco Feature Navigator is a web-based tool that enables you to determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image. You can search by feature or release. Under the release section, you can compare releases side by side to display both the features unique to each software release and the features in common.
To access Cisco 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 found at this URL:
Cisco Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Cisco Feature Navigator home page at the following URL:
Availability of Cisco IOS Software Images
Platform support for particular Cisco IOS software releases is dependent on the availability of the software images for those platforms. Software images for some platforms may be deferred, delayed, or changed without prior notice. For updated information about platform support and availability of software images for each Cisco IOS software release, refer to the online release notes or, if supported, Cisco Feature Navigator.
Contents
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Restrictions for the DFP Agent Subsystem
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Restrictions for the DFP Agent Subsystem
The DFP agent subsystem has the following restrictions:
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Information About the DFP Agent Subsystem
To configure the DFP agent subsystem feature, you must understand the following concepts:
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IOS SLB
The IOS SLB feature is an IOS-based solution that provides IP server load balancing. Using the IOS SLB feature, you can define a virtual server that represents a group of real servers in a cluster of network servers known as a server farm. In this environment, the clients connect to the IP address of the virtual server. When a client initiates a connection to the virtual server, the IOS SLB function chooses a real server for the connection based on a configured load-balancing algorithm.
For more information about IOS SLB, refer to the IOS Server Load Balancing feature document for Cisco IOS Release 12.2(14)S.
DFP
DFP is part of the ContentFlow architecture, and the mechanism by which servers provide feedback to IP load-balancing products. DFP enables workload agents in a local load-balancing environment, called DFP agents, to collect status information from one or more real host servers, convert the information to relative weights, and report the weights to load-balancing managers, called DFP managers, such as IOS SLB devices.
For more information about DFP, refer to the IOS Server Load Balancing feature document for Cisco IOS Release 12.2(14)S.
DFP Agents
DFP agents reside on IP server platforms, such as Windows NT, UNIX, and OS/390. When a DFP manager initiates a TCP connection with a DFP agent, the DFP agent begins collecting status information from one or more real host servers. The DFP agent then converts the information to relative weights and reports the weights to the DFP manager.
DFP Managers
DFP managers initiate TCP connections with DFP agents, receive relative weights of real servers from the DFP agents, and factor in those weights when load balancing the real servers.
DFP Agents Other Than IOS SLB
Prior to 12.1(8a)E, the DFP agent was implemented only in IOS SLB. The DFP agent subsystem feature enables client subsystems other than IOS SLB, such as General Packet Radio Service (GPRS), to act as DFP agents.
Multiple DFP Agents
The DFP agent subsystem feature supports the use of multiple DFP agents from different client subsystems (such as IOS SLB and GPRS) at the same time.
How to Configure the DFP Agent Subsystem
This section contains the following procedures:
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Defining the Port Number
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.
SUMMARY STEPS
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DETAILED STEPS
Displaying Information About DFP Agents
To obtain and display runtime information about DFP agents, enter the following commands.
SUMMARY STEPS
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DETAILED STEPS
Displaying Information About DFP and DFP Agents
To obtain and display runtime information about DFP and DFP agents, enter the following commands.
SUMMARY STEPS
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2.
DETAILED STEPS
Configuration Examples for the DFP Agent Subsystem
This section provides the following configuration example:
DFP Agent Subsystem Example
The following example shows the commands used to configure the DFP agent subsystem. Use these commands to accomplish the following tasks:
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Router(config)# ip dfp agent slbRouter(config-dfp)# interval 11Router(config-dfp)# password Password1 180Router(config-dfp)# port 2221Router(config-dfp)# inserviceAdditional References
For additional information related to the DFP agent subsystem, refer to the following references:
Related Documents
Standards
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.
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1 Not all supported standards are listed.
MIBs
No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified 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
1 Not all supported MIBs are listed.
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
http://tools.cisco.com/ITDIT/MIBS/servlet/index
If Cisco MIB Locator does not support the MIB information that you need, you can also obtain a list of supported MIBs and download MIBs from the Cisco MIBs page at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
To access Cisco MIB Locator, 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 found at this URL:
RFCs
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.
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1 Not all supported RFCs are listed.
Technical Assistance
Command Reference
This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.2T command reference publications.
Obsolete and Replaced Commands
Table 1 lists those commands that have been replaced since Cisco IOS Release 12.1(8a)E:
Table 1 Replaced DFP Agent Subsystem Commands
manager
The manager command has been replaced with the following set of commands:
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(see the ip dfp agent command)
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(see the interval (DFP agent) command)
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(see the password command)
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(see the port (DFP agent) command)
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(see the inservice (DFP agent) command)
debug ip dfp agent
To display debugging messages for the Dynamic Feedback Protocol (DFP) agent subsystem, use the debug ip dfp agent command in user EXEC or privileged EXEC mode. To disable debugging 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.
Command Modes
User EXEC or privileged EXEC mode
Command History
12.1(8a)E
This command was introduced.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
Usage Guidelines
This command displays debugging messages for the DFP agent subsystem.
Caution
Examples
The following example configures a DFP agent debugging session:
Router# debug ip dfp agentDFP debugging is onRouter#The following example stops all debugging:
Router# no debug allAll possible debugging has been turned offRouter#inservice (DFP agent)
To enable the Dynamic Feedback Protocol (DFP) agent for communication with a DFP manager, use the inservice command in DFP agent configuration mode. 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
The DFP agent is disabled and inactive.
Command Modes
DFP agent configuration
Command History
12.1(8a)E
This command was introduced.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
Usage Guidelines
A DFP agent is inactive until both of the following conditions are met:
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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 slbRouter(config-dfp)# inserviceRelated Commands
interval (DFP agent)
To configure a Dynamic Feedback Protocol (DFP) agent weight recalculation interval, use the interval command in DFP agent configuration mode. To restore the default setting, use the no form of this command.
interval seconds
no interval seconds
Syntax Description
seconds
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
12.1(8a)E
This command was introduced.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
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 slbRouter(config-dfp)# interval 11Related Commands
ip dfp agent
To identify a Dynamic Feedback Protocol (DFP) agent subsystem and enter DFP agent configuration mode, use the ip dfp agent command in global configuration mode. 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
Defaults
No DFP agent subsystems are identified.
Command Modes
Global configuration
Command History
12.1(8a)E
This command was introduced.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
Usage Guidelines
To discover the subsystem names that are available in your environment, enter the ip dfp agent ? command.
Examples
The following example identifies a DFP agent subsystem named slb and enters DFP agent configuration mode:
Router(config)# ip dfp agent slbRelated Commands
agent
Identifies a DFP agent to which IOS SLB can connect.
ip slb dfp
Configures DFP, supplies an optional password, and enters DFP configuration mode.
password
To configure a Dynamic Feedback Protocol (DFP) agent password for Message Digest Algorithm Version 5 (MD5) authentication, use the password command in DFP agent configuration mode. To remove the DFP agent password, use the no form of this command.
password [0 | 7] password [timeout]
no password
Syntax Description
Defaults
The password encryption default is 0 (unencrypted).
The password timeout default is 180 seconds.Command Modes
DFP agent configuration
Command History
12.1(8a)E
This command was introduced.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
Usage Guidelines
The password specified in this command must match the password specified for 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. Setting a longer timeout 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 Password1 and the timeout to 360 seconds:
Router(config)# ip dfp agent slbRouter(config-dfp)# password Password1 360Related Commands
port (DFP agent)
To define the port number to be used by the Dynamic Feedback Protocol (DFP) manager to connect to the DFP agent, use the port command in DFP agent configuration mode. 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 port number is defined.
Command Modes
DFP agent configuration
Command History
12.1(8a)E
This command was introduced.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
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 slbRouter(config-dfp)# port 2221Related Commands
show ip dfp
To display information about Dynamic Feedback Protocol (DFP) agents, use the show ip dfp command in privileged EXEC mode.
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 basic 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
12.1(8a)E
This command was introduced.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
Usage Guidelines
Detailed output for the show ip dfp command 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 basic information for DFP agent slb:
Router# show ip dfp agent slbUnexpected errors: 0DFP Agent for service: SLBPort: 666 Interval: 10Current passwd: <none> Pending passwd: <none>Passwd timeout: 0Inservice: yes AppActive: yesManager IP Address Timeout------------------ -------172.18.45.27 0The following example shows detailed information for DFP agent slb:
Router# show ip dfp agent slb detailUnexpected errors: 0DFP Agent for service: SLBPort: 666 Interval: 10Current passwd: <none> Pending passwd: <none>Passwd timeout: 0Inservice: yes AppActive: yesManager IP Address Timeout------------------ -------172.18.45.27 0Weight Table Report for Agent SLBWeights for Port: 80 Protocol: TCPIP Address Bind ID Weight--------------- ------- -------1.1.1.1 0 65535Weights for Port: 0 (wildcard) Protocol: 0 (wildcard)IP Address Bind ID Weight--------------- ------- -------0.0.0.0 65534 0Bind ID Table Report for Agent SLBBind IDs for Port: 80 Protocol: TCPBind ID Client IP Client Mask------- --------------- ---------------0 0.0.0.0 0.0.0.0
Related Commands
Glossary
Note
client subsystem—Users of the DFP agent function, such as IOS SLB.
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.
