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Table Of Contents
Related Features and Technologies
Supported Standards, MIBs, and RFCs
Adding a New Domain or Configuring an Existing Domain
Configuring the Domain Name Alias
Configuring the Server Address of a Domain
Verifying Boomerang Information on the DRP Agent
Adding a New Domain or Configuring an Existing Domain Example
Configuring the Domain Name Alias Example
Configuring the Server Address of a Domain Example
Configuring the IP TTL Example
Configuring the DNS TTL Example
alias (boomerang configuration)
server (boomerang configuration)
DRP Agent—Boomerang Support
Feature History
This document describes Boomerang Support in theDRP Agent in Cisco IOS Release 12.2(8)T. It includes the following sections:
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Supported Standards, MIBs, and RFCs
Feature Overview
When a boomerang Director Response Protocol (DRP) agent receives a Domain Name System (DNS) racing message from boomerang servers, the DRP extracts the domain name specified in the DNS message. The boomerang DRP agent can be configured on this specified domain using the new ip drp domain command.
A racing message occurs when DistributedDirector receives a DNS query from a DNS client for a host name that has the boomerang metric configured. DistributedDirector issues a DNS racing message to the different DRP agents. In the message, it instructs each DRP agent to respond directly to the client with the answer. The instruction also specifies whether the response should be sent at an absolute time or after a certain delay, which is determined by the configuration on DistributedDirector.
Boomerang is a DRP metric for DistributedDirector. When the boomerang metric is active, DistributedDirector instructs the DRP to send DNS responses directly back to the querying client. The DNS response contains the addresses of the sites associated with the specific DRP agent. All involved DRPs send back their DNS responses at the same time. The packet of the DRP that is nearest to the client in terms of delay will arrive first. The client may take the first answer and ignore subsequent ones, a standard behavior of all local DNS server implementations. The DRP agent allows configuration for full boomerang support. The commands described in this document can be used only on a DRP agent. The boomerang client is the DRP agent.
The DRP is a simple User Datagram Protocol (UDP)-based application developed by Cisco Systems. It enables the Cisco DistributedDirector product to query routers (DRP server agents) in the field for Border Gateway Protocol (BGP) and Interior Gateway Protocol (IGP) routing table metrics between distributed servers and clients. DistributedDirector, a separate standalone product, uses DRP to transparently redirect end-user service requests to the topologically closest responsive server. DRP enables DistributedDirector to provide dynamic, scalable, and "network intelligent" Internet traffic load distribution among multiple geographically dispersed servers.
Benefits
The boomerang metric provides a way to select a site with the fastest response time. Instead of relying on static maps, it dynamically recognizes congestion and link failures and avoids them.
Restrictions
Both DistributedDirector and the DRP agents should be able to communicate with each other using the boomerang protocol. Therefore, when DistributedDirector is upgraded to include the boomerang functionality, the DRP agents must be made aware of the presence of the boomerang protocol.
Related Features and Technologies
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Related Documents
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Supported Platforms
Boomerang support in the DRP Agent is supported on the following platforms:
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Determining Platform Support Through Cisco 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 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 quickly 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.
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:
Supported Standards, MIBs, and RFCs
Standards
No new or modified 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.
Configuration Tasks
See the following sections for configuration tasks for boomerang support in the DRP agent. Each task in the list is identified as either required or optional.
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Adding a New Domain or Configuring an Existing Domain
To add a new domain to the DistributedDirector client or to configure an existing domain, use the following command in global configuration mode. The boomerang client is the DRP agent, and this command is configured on the DRP agent. This command puts the client in boomerang configuration mode.
Router(config)# ip drp domain www.boom1.com
Specifies a domain to be added or configured and enters boomerang configuration mode. The domain in this example is named www.boom1.com.
Configuring the Domain Name Alias
To configure an alias name for a specified domain, use the following commands.
Configuring the Server Address of a Domain
To configure the server address for a specified boomerang domain, use the following commands.
Configuring the IP TTL
To configure the IP time to live (TTL) value for packets sent from the boomerang client to the DNS client in number of hops, use the following commands.
Configuring the DNS TTL
To configure the number of seconds for which an answer received from the boomerang client will be cached by the DNS client, use the ttl dns command in boomerang configuration mode.
Verifying Boomerang Information on the DRP Agent
Router# show ip drp boomerangDNS packets with unknown domain 0Domain www.boom1.comContent server 172.16.101.101 upOrigin server 0.0.0.0DNS A record requests 0Dropped (server down) 0Dropped (no origen server) 0Security failures 0Alias www.boom2.comDNS A record requests 0Step 1
Router# show ip drpDirector Responder Protocol Agent is enabled3 director requests:0 successful route table lookups0 successful measured lookups0 no route in table0 nortt0 DRP packet failures returned3 successful echos6 Boomerang requests0 Boomerang-raced DNS responsesAuthentication is enabled, using "DD" key-chainrttprobe source port is :53rttprobe destination port is:53
Troubleshooting Tips
If the ip drp domain domain-name command is configured on the DRP agent, but a corresponding server address is not specified for this domain name, then the content-server field defaults to 0.0.0.0. The show ip drp boomerang displays this information.
This configuration would effectively remove the DRP agent from the boomerang race. To include it again, enter boomerang configuration mode and specify a server address:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# server 172.16.101.101Configuration Examples
This section provides the following configuration examples:
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Adding a New Domain or Configuring an Existing Domain Example
In the following example, a domain named www.boom1.com is added on the boomerang client:
Router(config)# ip drp domain www.boom1.comRouter# show running-config..ip drp domain www.boom1.comConfiguring the Domain Name Alias Example
In the following example, the domain name alias is configured for www.boom1.com. The new alias for www.boom1.com is www.boom2.com:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# alias www.boom2.comRouter# show running-config..ip drp domain www.boom1.comalias www.boom2.comConfiguring the Server Address of a Domain Example
In the following example, the server address is configured for www.boom1.com. The server address for www.boom1.com is 172.16.101.101:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# server 172.16.101.101Router# show running-config..ip drp domain www.boom1.comcontent-server 172.16.101.101Configuring the IP TTL Example
In the following example, the number of hops that occur between the boomerang client and the DNS client before the boomerang response packet fails is 2:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# ttl ip 2Router# show running-config..ip drp domain www.boom1.comip-ttl 2Configuring the DNS TTL Example
In the following example, the number of seconds for which the DNS client can cache a boomerang reply from a boomerang client is configured to be 10:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# ttl dns 10Router# show running-config..ip drp domain www.boom1.comdns-ttl 10Command Reference
This section documents new commands. All other commands used with this feature are documented in the Cisco IOS command reference publications.
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alias (boomerang configuration)
To configure an alias name for a specified domain, use the alias command in boomerang configuration mode. To remove this command from the configuration file and restore the system to its default condition with respect to this command, use the no form of this command.
alias alias-name
no alias alias-name
Syntax Description
Defaults
No default behavior or values.
Command Modes
Boomerang configuration
Command History
Usage Guidelines
The alias command can be used only on a Director Response Protocol (DRP) agent. The boomerang client is the DRP agent.
Use the alias command to specify one or more alias names for an existing domain. Because the boomerang client maintains separate counters for requests received for each domain name (alias or otherwise), use the show ip drp boomerang command to view these counters for a specified domain name and each of its aliases.
Examples
In the following example, the domain name alias is configured for www.boom1.com. The new alias for www.boom1.com is www.boom2.com:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# alias www.boom2.comRouter# show running-config...ip drp domain www.boom1.comalias www.boom2.comRelated Commands
ip drp domain
To add a new domain to the DistributedDirector client or to configure an existing domain, use the ip drp domain command in global configuration mode. To remove this command from the configuration file and restore the system to its default condition with respect to this command, use the no form of this command.
ip drp domain domain-name
no ip drp domain domain-name
Syntax Description
Defaults
No default domain is configured.
Command Modes
Global configuration
Command History
Usage Guidelines
The ip drp domain command can be used only on a Director Response Protocol (DRP) agent. The boomerang client is the DRP agent.
Enabling this command puts the client in boomerang configuration mode.
Use the ip drp domain command to enter a new or existing domain name. Entering a new domain name creates a new domain, and entering an existing domain name allows the user to configure the specified domain. When a domain name is configured on the boomerang client, the user can configure specific parameters, such as server address, aliases, and time to live (TTL) values, for that domain.
When a Director Response Protocol (DRP) agent receives a Domain Name System (DNS) racing message from boomerang servers such as DistributedDirector, the DRP agent extracts the specified domain name (for example, www.cisco.com) in the DNS message.
Examples
In the following example, a domain named "www.boom1.com" is added on the boomerang client:
Router(config)# ip drp domain www.boom1.comRouter# show running-config...ip drp domain www.boom1.comRelated Commands
server (boomerang configuration)
To configure the server address for a specified boomerang domain, use the server command in boomerang configuration mode. To remove this command from the configuration file and restore the system to its default condition with respect to this command, use the no form of this command.
server server-ip-address
no server server-ip-address
Syntax Description
Defaults
No default behavior or values.
Command Modes
Boomerang configuration
Command History
Usage Guidelines
The server command can be used only on a Director Response Protocol (DRP) agent. The boomerang client is the DRP agent.
Use the server command to specify a server address that is to be associated with a given domain name. This configuration overrides the server-to-DRP agent association that is configured on DistributedDirector.
Examples
The following example configures the server for a domain named "www.boom1.com". The server address for www.boom1.com is 172.16.101.101:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# server 172.16.101.101Router# show running-config...ip drp domain www.boom1.comcontent-server 172.16.101.101Related Commands
show ip drp boomerang
To display the status of various boomerang domains, use the show ip drp boomerang command in privileged EXEC mode.
show ip drp boomerang [domain-name]
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
The show ip drp boomerang command can be used on the boomerang client to display the status of the various boomerang domains. The following information can be shown for each domain:
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Examples
To show the status of the boomerang domain named "www.boom1.com", enter the following command:
Router# show ip drp boomerang www.boom1.comDNS packets with unknown domain 0Domain www.boom1.comContent server 172.16.101.101 upOrigin server 0.0.0.0DNS A record requests 0Dropped (server down) 0Dropped (no origen server) 0Security failures 0Alias www.boom2.comDNS A record requests 0Related Commands
ttl dns
To configure the number of seconds for which an answer received from the boomerang client will be cached by the Domain Name System (DNS) client, use the ttl dns command in boomerang configuration mode. To remove this command from the configuration file and restore the system to its default condition with respect to this command, use the no form of this command.
ttl dns seconds
no ttl dns seconds
Syntax Description
seconds
Number of seconds for which an answer received from the boomerang client will be cached by the DNS client. Range is from 10 to 2147483647.
Defaults
No default behavior or values.
Command Modes
Boomerang configuration
Command History
Usage Guidelines
The ttl dns command can be used only on a Director Response Protocol (DRP) agent. The boomerang client is the DRP agent.
The ttl dns command configures the number of seconds for which the DNS client can cache a boomerang reply from a boomerang client.
Examples
In the following example, the number of seconds for which the DNS client can cache a boomerang reply from a boomerang client is configured as 10:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# ttl dns 10Router# show running-config...ip drp domain www.boom1.comdns-ttl 10Related Commands
ttl ip
To configure the IP time to live (TTL) value for the boomerang response packets sent from the boomerang client to the DNS client, use the ttl ip command in boomerang configuration mode. To remove this command from the configuration file and restore the system to its default condition with respect to this command, use the no form of this command.
ttl ip hops
no ttl ip hops
Syntax Description
hops
Number of hops that occur between the boomerang client and the DNS client before the boomerang response packet fails. Range is from 1 to 255.
Defaults
No default behavior or values.
Command Modes
Boomerang configuration
Command History
Usage Guidelines
The ttl ip command can be used only on a Director Response Protocol (DRP) agent. The boomerang client is the DRP agent.
The ttl ip command configures the maximum number of hops allowed between the boomerang client and the DNS client, after which the boomerang response packet fails. If the user wants to restrict the contending proxies only to nearby ones, the value of the ttl ip command can be set to a specific number within the allowed range. Any proxy outside of this range will be automatically disqualified in the boomerang race because its replies will never reach the DNS client. Because the ttl ip command specifies the number of hops for which a response from a client will live, it allows faraway proxies to avoid wasting bandwidth.
Examples
In the following example, the number of hops that occur between the boomerang client and the DNS client before the boomerang response packet fails is configured as 2:
Router(config)# ip drp domain www.boom1.comRouter(config-boomerang)# ttl ip 2Router# show running-config...ip drp domain www.boom1.comip-ttl 2Related Commands