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Cisco GSS CLI-Based Global Server Load-Balancing Configuration Guide (Software Version 2.0)
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Index
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Preface
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Introducing the Global Site Selector
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Configuring Resources
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Configuring Source Address Lists
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Configuring Domain Lists
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Configuring Keepalives
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Configuring Answers and Answer Groups
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Building and Modifying DNS Rules
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Configuring DNS Sticky
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Configuring Network Proximity
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Configuring DDoS Prevention
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Creating and Playing GSLB Configuration Files
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Displaying Global Server Load-Balancing Configuration Information
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Displaying GSS Global Server Load-Balancing Statistics
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Primary GSSM Global Server Load-Balancing Error Messages
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Sticky and Proximity XML Schema Files
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Glossary
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Table Of Contents
Configuring Answers and Answer Groups
Configuring and Modifying Answers
Logging in to the CLI and Enabling Privileged EXEC Mode
Configuring Keepalive VIP Answers
Configuring ICMP Keepalive VIP Answers
Configuring TCP Keepalive VIP Answer Settings
Configuring HTTP HEAD Keepalive VIP Answer Settings
Configuring KAL-AP Keepalive VIP Answer Settings
Configuring Scripted Keepalive VIP Answers
Configuring Multiple Keepalives for a VIP Answer Type
Configuring a Name Server-Type Answer
Suspending or Reactivating All Answers in a Location
Configuring and Modifying Answer Groups
Adding Answers to a CRA-Type Answer Group
Adding Answers to an NS-Type Answer Group
Adding Answers to a VIP-Type Answer Group
Adding or Deleting an Authority Domain in an Answer Group
Suspending or Reactivating All Answers in an Answer Group
Suspending or Reactivating an Answer in an Answer Group
Suspending or Reactivating All Answers in Answer Groups Associated with an Owner
Displaying Answer Group Properties
Configuring Answers and Answer Groups
This chapter describes how to create and configure answers and answer groups for your GSS network. It contains the following major sections:
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Configuring and Modifying Answers
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Configuring and Modifying Answers
In a GSS network, an answer refers to the resources that respond to content queries. When you create an answer using the primary GSSM, you are identifying a resource on your GSS network to which queries can be directed. This resource provides the requesting client D-proxy with the address of a valid host to serve the request.
GSS answers include the following:
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The GSS groups answers together as resource pools, also referred to as answer groups. From the available answer groups, the GSS can use a maximum of three possible response answer group and balance method clauses in a DNS rule to select the most appropriate resource that serves a user request. Each balance method provides a different algorithm for selecting one answer from a configured answer group. Each clause specifies that a particular answer group serve the request and a specific balance method be used to select the best resource from that answer group.
Depending on the type of answer, the GSS can further analyze DNS queries to choose the best host. For example, a request that is routed to a VIP associated with a Cisco CSS is routed to the best resource based on load and availability, as determined by the CSS. A request that is routed to a CRA is routed to the best resource based on proximity, as determined in a DNS race conducted by the GSS.
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Logging in to the CLI and Enabling Privileged EXEC Mode
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To log in to the primary GSSM and enable privileged EXEC mode at the CLI, perform the following steps:
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Otherwise, if you are using a direct serial connection between your terminal and the GSSM, use a terminal emulation program to access the CLI. For details about making a direct connection to the GSS device using a dedicated terminal and about establishing a remote connection using SSH or Telnet, see the Cisco Global Site Selector Getting Started Guide.
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gssm1.example.com>3.
gssm1.example.com> enablegssm1.example.com#Configuring a VIP-Type Answer
When configuring a VIP-type answer, you can configure one of several different keepalive types or multiple keepalive types to test for that answer. See the "Configuring Multiple Keepalives for a VIP Answer Type" section for more information on configuring multiple keepalives to test for an answer. For a KAL-AP keepalive, configure shared keepalives before you configure your answer. See Chapter 5, Configuring Keepalives for more information on creating shared keepalives.
To configure a VIP-type answer, use the answer vip ip_address command in global server load-balancing configuration mode.
The syntax of this command is as follows:
answer vip ip_address [name name | location name | activate | suspend]
After you enter the answer vip ip_address command, the prompt changes to the answer vip configuration mode where you can optionally specify and configure keepalives for your VIP-type answer.
The keywords and arguments for this command are as follows:
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For example, to create a VIP answer called SEC-LONDON1 and associate it with the London location, enter:
gssm1.example.com# configgssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# answer vip 10.86.209.232 name SEC-LONDON1 location LONDONgssm1.example.com(config-ansvip[ans-ip])To delete a VIP answer, enter:
gssm1.example.com# configgssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# no answer vip 10.86.209.232 name SEC-LONDON1 location LONDONgssm1.example.com(config-gslb)For more information on modifying existing answers, see the "Modifying an Answer" section.
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Configuring Keepalive VIP Answers
After you create an answer, you can choose to configure one of a variety of different keepalive types or multiple keepalive types to test for that answer.
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Configuring ICMP Keepalive VIP Answers
You can define the ICMP keepalives for your VIP answer by using the keepalive type icmp command in answer vip configuration mode. This command sends an ICMP echo message (ping) to the address specified for the VIP answer. The GSS determines the online status by the response received from the device, indicating simple connectivity to the network.
The syntax for this command is as follows:
keepalive type icmp [shared ip_address | retries number | successful-probes number]
The keywords and arguments for this command are as follows:
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For example, to configure an ICMP keepalive for the VIP-type answer servicing VIP address 10.86.209.232, enter:
gssm1.example.com(config-gslb)# answer vip 10.86.209.232gssm1.example.com(config-ansvip[ans-ip])# keepalive type icmp retries 2gssm1.example.com(config-ansvip[ans-ip])#See the "Configuring Multiple Keepalives for a VIP Answer Type" section for details on configuring multiple keepalives to test for a VIP-type answer.
Configuring TCP Keepalive VIP Answer Settings
You can define the TCP keepalive for your VIP answer by using the keepalive type tcp command in answer vip configuration mode. This command sends a TCP handshake to the address specified for the VIP answer and port number of the remote device to determine service viability (three-way handshake and connection termination method), returning the online status of the device.
The syntax for this command is as follows:
keepalive type tcp [shared ip_address | port number | retries number | successful-probes number | termination {graceful | reset}]
The keywords and arguments for this command are as follows:
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For example, to configure a TCP keepalive for the VIP-type answer servicing VIP address 192.168.200.1, enter:
gssm1.example.com(config-gslb)# answer vip 192.168.200.1gssm1.example.com(config-ansvip[ans-ip])# keepalive type tcp port 23 successful-probes 4gssm1.example.com(config-ansvip[ans-ip])#See the "Configuring Multiple Keepalives for a VIP Answer Type" section for details on configuring multiple keepalives to test for a VIP-type answer.
Configuring HTTP HEAD Keepalive VIP Answer Settings
You can define the HTTP HEAD keepalive for your VIP answer by using the keepalive type http-head command in answer vip configuration mode. This command sends a TCP-format HTTP HEAD request to an origin web server at the address specified for the VIP answer. The GSS determines the online status of the device in the form of an HTTP Response Status Code of 200 (for example, HTTP/1.0 200 OK) from the server as well as information on the web page status and content size.
The syntax for this command is as follows:
keepalive type http-head [host-tag domain_name | path path | port number | retries number | shared ip_address | successful-probes number | termination {graceful | reset}]
The keywords and arguments for this command are as follows:
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For example, to configure an HTTP HEAD keepalive for the VIP-type answer servicing VIP address 192.168.200.1, enter:
gssm1.example.com(config-gslb)# answer vip 192.168.200.1gssm1.example.com(config-ansvip[ans-ip])# keepalive type http-head host-tag WWW.HOME.COM termination gracefulgssm1.example.com(config-ansvip[ans-ip])#See the "Configuring Multiple Keepalives for a VIP Answer Type" section for details on configuring multiple keepalives to test for a VIP-type answer.
Configuring KAL-AP Keepalive VIP Answer Settings
You can define the KAL-AP keepalive for your VIP answer by using the keepalive type kalap command in answer vip configuration mode. This command sends a detailed query to the Cisco CSS or CSM at the address specified for the VIP answer to extract the load and availability. The GSS determines the online status when the SLBs respond with information about a hosted domain name, host VIP address, or a configured tag on a content rule.
The syntax for this command is as follows:
keepalive type kalap {tag ip_address {tag_name} | vip ip_address}
The keywords and arguments for this command are as follows:
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For example, to configure a KAL-AP keepalive for the VIP-type answer servicing VIP address 192.168.200.1, enter:
gssm1.example.com(config-gslb)# answer vip 192.168.200.1gssm1.example.com(config-ansvip[ans-ip])# keepalive type kalap tag 192.168.50.41 TAG1gssm1.example.com(config-ansvip[ans-ip])#See the "Configuring Multiple Keepalives for a VIP Answer Type" section for details on cofiguring multiple keepalives to test for a VIP-type answer.
The Content and Application Peering Protocol (CAPP) may not recognize dropped fragments when a KAL-AP keepalive spans multiple datagrams due to large payloads. When the KAL-AP keepalive spans multiple datagrams and one of the spanned packets is dropped, the GSS does not retry the request. Instead, the GSS waits until the next period and sends the packets again, which results in the dropped datagram not getting updated load values on the VIPs that expect them. This behavior occurs when the GSS consumes the full datagram (roughly 1.4 K) with tag names or VIP addresses. Otherwise, all data fits in a single datagram.
Use the VIP format for KAL-AP when you need the GSS to send a detailed query on load for hundreds of VIPs configured to a single primary or optional secondary (backup) IP address. You can also use the tag format for KAL-AP. However, you must limit the length of the tag name to ensure that the packets do not exceed 1.4K.
Configuring Scripted Keepalive VIP Answers
You can define the Scripted keepalives for your VIP answer by using the keepalive type scripted-kal command in answer vip configuration mode. This command allows you to specify a KAL name and maximum load in order to add a Scripted keepalive probe to the VIP.
The syntax for this command is as follows:
keepalive type scripted-kal kal-name name max-load max load value
The keywords and arguments for this command are as follows:
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For example, to configure a Scripted keepalive for the VIP-type answer servicing VIP address 192.168.200.1, enter:
gssm1.example.com(config-gslb)# answer vip 192.168.200.1gssm1.example.com(config-ansvip[ans-ip])# keepalive type scripted-kal kal-name samplekal max-load 50gssm1.example.com(config-ansvip[ans-ip])#See the "Configuring Multiple Keepalives for a VIP Answer Type" section for details on configuring multiple keepalives to test for a VIP-type answer.
Configuring Multiple Keepalives for a VIP Answer Type
The primary GSSM allows you to assign multiple keepalives and/or destination ports for a single VIP answer. You can configure a maximum of five different keepalives for a VIP answer, in a mix and match configuration of ICMP, TCP, HTTP HEAD, and KAL-AP VIP keepalive types. However, the primary GSSM supports only a single usage of a shared keepalive and a single KAL-AP keepalive when you specify multiple keepalive types.
For TCP or HTTP HEAD keepalives, you may also specify different destination ports. The multi-port keepalive capability allows you to monitor a single server and check responses from multiple ports. If the keepalives are successful, the GSS device considers the resource active and continues to redirect client traffic to the server. Servers that yield unsuccessful connections are marked as unavailable; subsequent successful connections to the server will reinstate it as available to be used as a resource.
When using multiple keepalive types, the VIP answer status is a logical AND function of all keepalive probes associated with an answer, resulting in a consolidation of results from each answer.
For example, to configure a group of five keepalives that include a mix of shared and nonshared TCP-, -ICMP, and HTTP HEAD-type keepalives servicing VIP address 192.168.200.1, enter:
gssm1.example.com(config-gslb)# answer vip 192.168.200.1gssm1.example.com(config-ansvip[ans-ip])# keepalive type tcp port 443 ip-address 192.168.50.41 retries 3 successful-probes 4 termination resetgssm1.example.com(config-ansvip[ans-ip])# keepalive type tcp port 80 retries 4gssm1.example.com(config-ansvip[ans-ip])# keepalive type http-head port 8080 ip-address 10.86.209.22 termination gracefulgssm1.example.com(config-ansvip[ans-ip])# keepalive type icmp ip-address 10.86.209.4 sharedgssm1.example.com(config-ansvip[ans-ip])# keepalive type tcp port 1650 ip-address 10.86.209.4 sharedgssm1.example.com(config-ansvip[ans-ip])# exitgssm1.example.com(config-gslb)#To configure TCP- and HTTP HEAD-type keepalives for multiple ports for the VIP-type answer named MPORT_KALE_MIX that services VIP address 192.168.200.1, enter:
gssm1.example.com(config-gslb)# answer vip 192.168.200.1 name MPORT_KALE_MIXgssm1.example.com(config-ansvip[ans-ip])# keepalive type tcp port 80gssm1.example.com(config-ansvip[ans-ip])# keepalive type tcp port 443gssm1.example.com(config-ansvip[ans-ip])# keepalive type http-head port 8080gssm1.example.com(config-ansvip[ans-ip])# exitgssm1.example.com(config-gslb)#
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To configure KAL-AP-, TCP- and HTTP HEAD-type keepalives for the VIP-type answer servicing VIP address 192.168.200.1, enter:
gssm1.example.com(config-gslb)# answer vip 192.168.200.1gssm1.example.com(config-ansvip[ans-ip])# keepalive type kalap tag 192.168.50.41 TAG1gssm1.example.com(config-ansvip[ans-ip])# keepalive type tcp port 80gssm1.example.com(config-ansvip[ans-ip])# keepalive type tcp port 443gssm1.example.com(config-ansvip[ans-ip])# keepalive type http-head port 8080gssm1.example.com(config-ansvip[ans-ip])# exitgssm1.example.com(config-gslb)#Configuring a CRA-Type Answer
The content routing agent (CRA) answer type relies on content routing agents and the GSS to choose a suitable answer for a given query based on the proximity of two or more possible hosts to the requesting D-proxy.
With the CRA-type answer, the requests received from a particular D-proxy are served by the content server that responds first to the request. The response time is measured using a DNS race and is coordinated by the GSS and content routing agents running on each content server. In the race, multiple hosts respond simultaneously to a request. The server with the fastest response time (the shortest network delay between itself and the client's D-proxy) is chosen to serve the content.
The CRA-type answer is designed to work with the GSS when you select the boomerang balance method with a DNS rule (utilizing the boomerang server component of the GSS).
Closeness is determined when multiple hosts reply to the requesting D-proxy simultaneously in what is referred to as a "DNS race." The GSS coordinates the start of the race so that all CRAs initiate their response at the same time. The first DNS reply to reach the D-proxy is chosen by the name server as the host containing the answer.
To configure a CRA-type answer, use the answer cra ip_address command in global server load-balancing configuration mode. The syntax of this command is as follows:
answer cra ip_address [enable | disable | delay number | name name | location name | activate | suspend]
The keywords and arguments for this command are as follows:
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For example, to create a CRA-type answer with a one-way delay, enter:
gssm1.example.com# configgssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# answer cra 10.86.209.22 name CRA-ANS1 delay 3gssm1.example.com(config-gslb)To delete a CRA-type answer, enter:
gssm1.example.com(config-gslb)# no answer cra 10.86.209.22 name CRA-ANS1 delay 3gssm1.example.com(config-gslb)For information on modifying existing answers, see the "Modifying an Answer"section.
Configuring a Name Server-Type Answer
A name server (NS)-type answer specifies the IP address of a DNS name server to which DNS queries are forwarded from the GSS. Using the name server forwarding feature, queries are forwarded to a non-GSS name server for resolution, with the answer passed back to the GSS name server and from there to the requesting D-proxy. The name server-type answer acts as a guaranteed fallback resource. A fallback resource can resolve requests that the GSS cannot resolve itself either because the requested content is unknown to the GSS or because the resources that typically handle such requests are unavailable.
To configure a NS-type answer, use the answer ns ip_address command in global server load-balancing configuration mode. The syntax of this command is:
answer ns ip_address [enable | disable | name name | domain name | location name | activate | suspend]
The keywords and arguments for this command are as follows:
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For example, to create an NS-type answer that specifies a domain name server, enter:
gssm1.example.com# configgssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# answer ns 10.86.209.4 domain WWW.HOME.COM enablegssm1.example.com(config-gslb)To delete a NS-type answer, enter:
gssm1.example.com(config-gslb)# no answer ns 10.86.209.4 domain WWW.HOME.COM enablegssm1.example.com(config-gslb)For information on modifying existing answers, see the "Modifying an Answer" section.
Modifying an Answer
Once you have configured your answers, you can modify them at any time. However, once an answer is created and named, you cannot modify its type (for example, from VIP to CRA), its IP address, or its name.
To modify an existing answer, perform the following steps:
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The syntax of this command is as follows:
answer {cra | ns | vip}
The options are as follows:
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For example, to first display the answer property settings, and then change the one-way delay time for an existing CRA-type answer, enter:
gssm1.example.com(config-gslb)# show gslb-config answer...answer cra 192.168.50.41 delay 2 activateanswer ns 172.16.27.4 domain EXAMPLE.COM activateanswer vip 172.16.27.6 name ansvip2 activatekeepalive type tcp port 180 activatekeepalive type tcp port 88 activate...gssm1.example.com(config-gslb)# answer cra 192.168.50.41 delay 5gssm1.example.com(config-gslb)#In order to modify a named answer, you must specify its name, type, and IP address. For example, to modify the answer named ANSVIP2, enter:
gssm1.example.com(config-gslb)# answer vip 172.16.27.6 name ANSVIP2 delay 100gssm1.example.com(config-gslb)#Displaying Answer Properties
You can use the show gslb-config answer command to display the current property settings for all answer types.
The syntax of this command is as follows:
show gslb-config answer
For example, enter:
gssm1.example.com(config-gslb)# show gslb-config answeranswer cra 192.168.50.41 delay 2 activeanswer ns 172.16.27.4 domain EXAMPLE.COM activeanswer vip 172.16.27.6 name ansvip2 activekeepalive type tcp port 180 activeanswer vip 192.168.50.30 activekeepalive type tcp port 88 activeanswer vip 192.168.50.2 name ansvip activekeepalive type icmp activekeepalive type tcp port 88 activekeepalive type tcp port 80 activegssm1.example.com(config-gslb)#To display the property settings based on the IP address and answer type, enter:
gssm1.example.com(config-gslb)# show gslb-config answer 172.16.27.6 vipanswer vip 172.16.27.6 name ansvip2 activekeepalive type tcp port 180 activegssm1.example.com(config-gslb)#To display the property settings based on an answer name, enter:
gssm1.example.com(config-gslb)# show gslb-config answer ansvip2answer vip 172.16.27.6 name ansvip2 activekeepalive type tcp port 180 activegssm1.example.com(config-gslb)#Suspending an Answer
You can temporarily stop the GSS from using an active answer by modifying the answer with the suspend keyword in the answer command. Suspending prevents that answer from being used by any of the currently configured DNS rules.
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To suspend an answer, perform the following steps:
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For example, to suspend the NS-type answer that queries the domain server at EXAMPLE.COM, enter:
gssm1.example.com(config-gslb)# show gslb-config answer...answer cra 192.168.50.41 delay 2 activeanswer ns 172.16.27.4 domain EXAMPLE.COM activeanswer vip 172.16.27.6 name ansvip2 activekeepalive type tcp port 180 active...gssm1.example.com(config-gslb)# answer ns 172.16.27.4 domain EXAMPLE.COM suspendgssm1.example.com(config-gslb)#To reactivate a suspended answer, use the activate feature (see the "Reactivating an Answer" section).
Reactivating an Answer
You can reactivate a suspended answer by modifying the specific answer with the activate keyword (for the answer command).
To reactivate an answer, perform the following steps:
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For example, to reactivate the NS-type answer that queries the domain server at EXAMPLE.COM, enter:
gssm1.example.com(config-gslb)# show gslb-config answer...answer cra 192.168.50.41 delay 2 activeanswer ns 172.16.27.4 domain EXAMPLE.COM suspendanswer vip 172.16.27.6 name ansvip2 activekeepalive type tcp port 180 active...gssm1.example.com(config-gslb)# answer ns 172.16.27.4 domain EXAMPLE.COM activategssm1.example.com(config-gslb)#Suspending or Reactivating All Answers in a Location
You can group and manage answers according to an established GSS location. Using a location to manage your answers makes it easier for you to quickly suspend or activate answers in a particular area of your network, for example, shutting down one or more data centers to perform software upgrades or regular maintenance.
The GSS automatically detects and routes requests around suspended answers.
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To suspend or reactivate answers based on their location, use the location command with the suspend-all-answers and activate-all-answers options.
Use the show gslb-config location command to display the currently configured locations. See Chapter 2, Displaying Resource Information, for more information about this command.
For example, to suspend all answers based on the location Normandy, enter:
gssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# location Normandy suspend-all-answersgssm1.example.com(config-gslb)#To reactivate all answers based on the location Normandy, enter:
gssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# location Normandy activate-all-answersgssm1.example.com(config-gslb)#Deleting an Answer
Caution
To delete an answer, perform the following steps:
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For example, to delete the VIP-type answer that queries IP address 192.168.50.30 and all keepalives for that answer, enter:
gssm1.example.com(config-gslb)# show gslb-config answer...answer cra 192.168.50.41 delay 2 activateanswer ns 172.16.27.4 domain EXAMPLE.COM activateanswer vip 172.16.27.6 name ansvip2 activatekeepalive type tcp port 180 activateanswer vip 192.168.50.30 activatekeepalive type tcp port 88 activateanswer vip 192.168.50.2 name ansvip activatekeepalive type icmp activatekeepalive type tcp port 88 activatekeepalive type tcp port 80 activatekeepalive type tcp activate...gssm1.example.com(config-gslb)# no answer vip 192.168.50.30gssm1.example.com(config-gslb)#In order to delete a named answer, you must specify its name, type, and IP address. For example, to delete the answer named ANSVIP2, you must enter:
gssm1.example.com(config-gslb)# no answer vip 172.16.27.6 name ANSVIP2gssm1.example.com(config-gslb)#Configuring and Modifying Answer Groups
Answer groups are lists of GSS resources that are candidates to respond to DNS queries received from a user for a hosted domain. By using the DNS rules feature, you associate these lists of network resources with one of the following balance methods used to resolve the request:
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A DNS rule can have a maximum of three balance clauses. Each balance clause specifies a different answer group from which an answer can be chosen after taking load threshold, order, and weight factors into account for each answer.
Before creating your answer groups, configure the answers that make up those groups. See the "Configuring and Modifying Answers" section for more information on creating GSS answers.
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Creating an Answer Group
You can configure up to 1000 answer groups on the primary GSSM. To create an answer group, use the answer-group command in global server load-balancing configuration mode.
The syntax of this command is as follows:
answer-group name {owner name type {cra | ns | vip}}
After you enter the answer-group command, the prompt changes to the answer group configuration mode, where you add previously configured answers to the group.
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The maximum number of answers that you can place in each of these answer groups is 20 for a CRA answer group, 30 for an NS answer group, and 100 for a VIP answer group.
For example, to create a VIP answer group, enter:
gssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# answer-group ANSGRPVIP1 owner WEB-SERVICES type vipgssm1.example.com(config-gslb-agvip[ag-name])#For example, to delete a VIP answer group, enter:
gssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# no answer-group ANSGRPVIP1 owner WEB-SERVICES type vipgssm1.example.com(config-gslb)#This section contains the following topics:
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Adding Answers to a CRA-Type Answer Group
After you create a CRA-type answer group, add previously configured CRA-type answers to the group using the answer-add command in the answer group configuration mode.
The syntax for this command is as follows:
answer-add ip_address [activate | name | suspend]
The keywords and arguments for this command are as follows:
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For example, to add answers to and configure a CRA answer group, enter:
gssm1.example.com(config-gslb-agcra[ag-name])# answer-add 192.168.10.1 name www-boston-1gssm1.example.com(config-gslb-agcra[ag-name])# answer-add 192.172.24.1 name www-ny-1gssm1.example.com(config-gslb-agcra[ag-name])# answer-add 192.186.14.1 name www-atlanta-1gssm1.example.com(config-gslb-agcra[ag-name])#To delete an answer from a CRA answer group, enter:
gssm1.example.com(config-gslb-agcra[ag-name])# no answer-add 192.186.14.1 name www-atlanta-1Adding Answers to an NS-Type Answer Group
After you create an NS-type answer group, add previously configured NS-type answers to the group using the answer-add command in the answer group configuration mode.
The syntax for this command is as follows:
answer-add ip_address [name | order number | weight number | activate | suspend]
The keywords and arguments for this command are as follows:
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For more information on the order and weight settings, see the "Balance Methods" section in Chapter 1, Introducing the Global Site Selector.
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For example, to add answers to and configure an NS answer group, enter:
gssm1.example.com(config-gslb-agns[ag-name])# answer-add 192.168.10.1 name www-zurich-1 order 10gssm1.example.com(config-gslb-agns[ag-name])# answer-add 192.172.20.1 name www-barcelona-1 order 20gssm1.example.com(config-gslb-agns[ag-name])# answer-add 192.188.30.1 name www-brussels-30gssm1.example.com(config-gslb-agns[ag-name])#To delete an answer from an NS answer group, enter:
gssm1.example.com(config-gslb-agns[ag-name)# no answer-add 192.168.10.1 name www-zurich-1 order 10Adding Answers to a VIP-Type Answer Group
After you create a VIP-type answer group, add previously configured VIP-type answers to the group using the answer-add command in the answer group configuration mode.
The syntax for this command is as follows:
answer-add ip_address [name | load-threshold number | order number | weight number | activate | suspend]
The keywords and arguments for this command are as follows:
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For more information on the order, weight, and load threshold settings, see the "Balance Methods" section in Chapter 1, Introducing the Global Site Selector.
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For example, to add answers to and configure a VIP answer group, enter:
gssm1.example.com(config-gslb-agvip[ag-name])# answer-add 192.168.30.1 name www-hk-1 weight 1gssm1.example.com(config-gslb-agvip[ag-name])# answer-add 192.174.20.1 name www-sf-1 weight 2gssm1.example.com(config-gslb-agvip[ag-name])# answer-add 192.188.40.1 name www-london-1 weight 4gssm1.example.com(config-gslb-agvip[ag-name])#To delete an answer from a VIP answer group, enter:
gssm1.example.com(config-gslb-agvip[ag-name])# no answer-add 192.168.30.1 name www-hk-1 weight 1Modifying an Answer Group
Once you create your answer groups, use the CLI in the primary GSSM to make modifications to their configurations, such as adding and removing answers, or changing the order, weight, and load thresholds of the individual answers. Answers can belong to more than one answer group. However, once you add answers to an answer group, you cannot change the type of an answer group (for example, from VIP to CRA).
To modify an answer group, perform the following steps:
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For example, to change the order setting for an answer in the VIP answer group ANSGRPVIP4, enter:
gssm1.example.com(config-gslb)# answer-group ANSGRPVIP4 owner WEB-SERVICES type vipgssm1.example.com(config-gslb-agvip[ag-name])# answer-add 192.168.30.1 name www-hk-1 order 10 comments "CHANGED ORDER 12/01/05"gssm1.example.com(config-gslb-agvip[ag-name])#To change the owner of the NS answer group ANSGRPNS2, enter:
gssm1.example.com(config-gslb)# answer-group ANSGRPNS2 owner E-COMMERCE type nsgssm1.example.com(config-gslb-agns[ag-name])#Adding or Deleting an Authority Domain in an Answer Group
Start of Authority (SOA) record TTLs are required when forming negative responses for DNS queries. Be aware that you do not have to configure any SOA records on the GSS to use in the negative response. Instead, you configure a name service (NS) answer on the GSS that specifies the IP address of the authority name server for the domain and the domains hosted on the name server.
To configure as NS answer on the GSS, use the auth-domain command in answer group configuration mode. The no form of this command deletes an authority domain in an answer group. The syntax of the command is as follows:
auth-domain domain-name
no auth-domain domain-name
Note
To add an authority domain, perform the following steps:
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gssm1.example.com# configgssm1.example.com (config)# gslbgssm1.example.com (config-gslb)# answer ns 1.2.3.4 name ns1 activate2.
gssm1.example.com (config-gslb)# answer-group ag1 owner System type nsgssm1.example.com (config-gslb-agns)# answer-add 1.2.3.4 name ns1gssm1.example.com (config-gslb-agns)# auth-domaain soa.testgssm1.example.com (config-gslb-agns)# auth-domain soa.orgUpon completion, NS answer 1.2.3.4 is the authoritative name server for the soa.test and soa.org domains, NS 1 answer is the authority for the configured domains soa.test and soa.org, and the GSS is the authority for A record abc.soa.test.
With this configuration, the negative responses for soa.test that need SOA records are included. If there is a cached SOA from answer NS 1, it is used in the negative response. Otherwise, the GSS queries name server ns1 for an SOA record for the domain soa.test, uses it in the negative response, and then caches it.
You do not need to configure SOA records on the GSS for the domains for which GSS is authoritative (that is, certain types of resouce records). GSS will always obtain the SOA record from the primary name server that is authoritative for the zone.
Suspending or Reactivating All Answers in an Answer Group
You can temporarily stop the GSS from using all answers in an active answer group by modifying the answer group with the no activate-all-answers command in answer group configuration mode. When you suspend all answers in an answer group, you prevent that answer group from being used by any of the currently configured DNS rules. Suspending the answers in one answer group also affects any other answer groups to which those answers belong.
To reactivate the answers in the answer group, use the activate-all-answers command in the answer group configuration mode for a specific answer group.
To suspend all answers in an answer group, perform the following steps:
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For example, to suspend all answers in the vip-type answer group ANSGRPVIP4, enter:
gssm1.example.com(config-gslb)# answer-group ANSGRPVIP4 owner WEB-SERVICES type vipgssm1.example.com(config-gslb-agvip[ag-name])# no activate-all-answersgssm1.example.com(config-gslb-agvip[ag-name])#To reactivate all answers in a suspended answer group, use the activate-all-answers command.
For example, enter:
gssm1.example.com(config-gslb)# answer-group ANSGRPVIP4 owner WEB-SERVICES type vipgssm1.example.com(config-gslb-agvip[ag-name])# activate-all-answersgssm1.example.com(config-gslb-agvip[ag-name])#Suspending or Reactivating an Answer in an Answer Group
You can temporarily stop the GSS from using an answer in an active answer group by modifying the answer group with the suspend keyword in the answer-add command. Enter this command in answer group configuration mode. Suspending prevents that answer in the answer group from being used by any of the currently configured DNS rules.
Note
To reactivate an answer in the answer group, use the active option (for the answer-add command) in the answer group configuration mode.
To suspend an answer in an answer group, perform the following steps:
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For example, to suspend the answer www-sf-1 in the vip-type answer group ANSGRPVIP4, enter:
gssm1.example.com(config-gslb)# answer-group ANSGRPVIP4 owner WEB-SERVICES type vipgssm1.example.com(config-gslb-agvip[ag-name])# answer-add 192.168.30.1 suspendgssm1.example.com(config-gslb-agvip[ag-name])#For example, to reactivate a suspended answer in an answer group with the activate command, enter:
gssm1.example.com(config-gslb)# answer-group ANSGRPVIP4 owner WEB-SERVICES type vipgssm1.example.com(config-gslb-agvip[ag-name])# answer-add 192.168.30.1 activategssm1.example.com(config-gslb-agvip[ag-name])#Suspending or Reactivating All Answers in Answer Groups Associated with an Owner
You can group and manage answers added to answer groups according to the GSS owner. Using a GSS owner to manage your answer groups enables you to quickly suspend or activate related answers.
To suspend or reactivate all answers in answer groups associated with a GSS owner, use the suspend-all-answers and activate-all-answers keywords (for the owner command).
To display the currently configured owners, answers, and answer groups, use the show gslb-config answer-group command.
For example, to suspend all answers in answer groups associated with the owner WEB-SERVICES, enter:
gssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# owner WEB-SERVICES suspend-all-answersgssm1.example.com(config-gslb)#To reactivate all answers in answer groups associated with the owner WEB-SERVICES, enter:
gssm1.example.com(config)# gslbgssm1.example.com(config-gslb)# owner WEB-SERVICES activate-all-answersgssm1.example.com(config-gslb)#Displaying Answer Group Properties
You can display the current property settings for all answer groups by entering the show gslb-config answer-group command.
The syntax of this command is as follows:
show gslb-config answer-group
For example, enter:
gssm1.example.com(config-gslb)# show gslb-config answer-group...answer-group AGROUP1 owner "OWNER1" type nsanswer-group AGROUP2 owner "OWNER2" type craanswer-group AGROUP3 owner System type vip...To display the properties for an answer group based on an answer group name, enter:
gssm1.example.com(config-gslb)# show gslb-config answer-group ANGROUP1answer-group AGROUP1 owner "OWNER1" type nsDeleting an Answer Group
Caution
Before deleting an answer group, verify that none of your DNS rules reference the answer group that you are about to delete. If necessary, deselect the answer group from the DNS rule. See Chapter 7, Building and Modifying DNS Rules, for information about modifying a DNS rule.
Deleting an answer group does not delete the answers contained in the answer group.
To delete an answer group, perform the following steps:
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For example, to delete the VIP-type answer group ANSGRPVIP1, enter:
gssm1.example.com(config-gslb)# show gslb-config answer-groupanswer-group ANSGRPVIP1 owner OWNR1 type vipanswer-group ANSGRPVIP2 owner System type vipgssm1.example.com(config-gslb)# no answer-group ANSGRPVIP1gssm1.example.com(config-gslb)#Where to Go Next
Chapter 7, Building and Modifying DNS Rules, describes how to construct the DNS rules that govern all global server load balancing on your GSS network.
