Cisco GSS Global Server Load-Balancing Configuration Guide (Software Version 1.2) - Configuring Answers and Answer Groups [Cisco ACE GSS 4400 Series Global Site Selector Appliances]

Table Of Contents

Configuring Answers and Answer Groups

Configuring and Modifying Answers

Creating a VIP-Type Answer

Configuring Shared ICMP Keepalive VIP Answer Settings

Configuring Shared TCP Keepalive VIP Answer Settings

Configuring Shared HTTP HEAD Keepalive VIP Answer Settings

Configuring Shared KAL-AP Keepalive VIP Answer Settings

Creating a CRA-Type Answer

Creating a Name Server-Type Answer

Modifying an Answer

Suspending an Answer

Reactivating an Answer

Suspending or Reactivating All Answers in a Location

Deleting an Answer

Configuring and Modifying Answer Groups

Creating an Answer Group

Modifying an Answer Group

Suspending or Reactivating Answers in an Answer Group

Suspending or Reactivating All Answers in an Answer Group Associated with an Owner

Deleting an Answer Group

Where to Go Next

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:

•Configuring and Modifying Answers

•Configuring and Modifying Answer Groups

•Where to Go Next

Configuring and Modifying Answers

In a GSS network, the term answers 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 and that can provide the requesting client D-proxy with the address of a valid host to serve their request.

GSS answers include the following:

•VIP—Virtual IP (VIP) addresses associated with an SLB such as the Cisco CSS, Cisco CSM, Cisco IOS-compliant SLB, LocalDirector, a web server, cache, or other geographically dispersed SLBs in a global network deployment.

•Name Server—A configured DNS name server on your network that can answer queries that the GSS cannot resolve.

•CRA—Content routing agents that use a resolution process called DNS race to send identical and simultaneous responses back to a user's D-proxy.

The GSS groups answers together as resource pools, also referred to as answer groups. From the available answer groups, the GSS can use up to 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, further intelligence can be applied to DNS queries by the GSS 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.

This section includes the following procedures:

•Creating a VIP-Type Answer

•Creating a CRA-Type Answer

•Creating a Name Server-Type Answer

•Modifying an Answer

•Suspending an Answer

•Reactivating an Answer

•Suspending or Reactivating All Answers in a Location

•Deleting an Answer

Creating a VIP-Type Answer

The VIP-type answer refers to a virtual IP address (VIP) associated with an SLB device such as a Cisco CSS or CSM. When the GSS receives requests for content that is managed by an SLB, the GSS returns an A-record containing the VIP of the SLB that manages the content.

When configuring a VIP-type answer you have the option to configure one of a variety of different keepalive types to test for that answer. For a KAL-AP keepalive, configure shared keepalive before you configure your answer. Refer to Chapter 5, Configuring Keepalives for more information on creating shared keepalives.

Note Once an answer is created, you cannot modify the answer type (for example, from VIP to CRA).

To configure a VIP-type answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (Figure 6-1).

Figure 6-1 Answers List Page

3. Click the Create Answer icon. The Creating New Answer detail page appears (Figure 6-2).

Figure 6-2 Creating New Answer Details Page

4. In the Type field, click the VIP option button. The VIP Answer section appears in the details page (Figure 6-3).

Figure 6-3 Creating New Answer—VIP Details Page

5. In the Name field, enter a name for the VIP-type answer that you are creating. Specifying a name for an answer is an optional step.

6. From the Location drop-down list, select a GSS location that corresponds to the answer. Specifying a location for an answer is an optional step unless you are assigning a location that is associated with a proximity zone to the answer. For details about creating a location, refer to Chapter 2, Configuring Resources.

7. In the VIP address field, enter the VIP address to which the GSS will forward requests.

8. Choose from one of these five keepalive types for your VIP answer:

• None—Does not send keepalive queries to the VIP. The GSS assumes that the VIP is always alive.

• ICMP—Sends an ICMP echo message (ping) to the specified address. The GSS determines the online status by the response received from the device, indicating simple connectivity to the network.

• TCP—Sends a TCP handshake to the specified IP address 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.

• HTTP HEAD—Sends a TCP-format HTTP HEAD request to an origin web server at a specified address. 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.

• KAL-AP—Sends a detailed query to the Cisco CSS or CSM to extract 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 following sections describe how to configure the properties for the individual VIP keepalives. The default values used for each of the VIP keepalives are determined by the values specified in the Global Keepalive Properties details page.

•Configuring Shared ICMP Keepalive VIP Answer Settings

•Configuring Shared TCP Keepalive VIP Answer Settings

•Configuring Shared HTTP HEAD Keepalive VIP Answer Settings

•Configuring Shared KAL-AP Keepalive VIP Answer Settings

Configuring Shared ICMP Keepalive VIP Answer Settings

To define the shared ICMP keepalive for your VIP answer, perform the following procedure. Refer to Figure 6-4 when performing this procedure.

Figure 6-4 Answer Details Page—ICMP KeepAlive VIP Answer

1. If necessary, uncheck the VIP Address check box and select an ICMP-type shared keepalive from the Shared ICMP Keepalive drop-down list. The VIP Address check box is automatically checked to instruct the GSS to send an ICMP echo message (ping) to the VIP address of the remote device and determine the online status.

2. If the ICMP global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section:

•In the Number of Retries field, specify the number of times the GSS retransmits an ICMP echo request packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries you increase the detection time. Reducing the number of retries has the reverse effect. The valid entries are from 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value.

•In the Number of Successful Probes field, specify the number of consecutive successful ICMP keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The valid entries are from 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value.

Note For more information on keepalive detection time, refer to Chapter 1, Introducing the Global Site Selector, the "Keepalives" section.

3. Click the Submit button to save your ICMP keepalive VIP answer and return to the Answers list page.

Configuring Shared TCP Keepalive VIP Answer Settings

To define the shared TCP keepalive for your VIP answer, perform the following procedure. Refer to Figure 6-5 when performing this procedure.

Figure 6-5 Answer Details Page—TCP KeepAlive VIP Answer

1. If necessary, uncheck the VIP Address check box and choose a TCP-type shared keepalive from the Shared TCP Keepalive drop-down list. The VIP Address check box is automatically checked to instruct the GSS to send a TCP keepalive to the VIP address of the remote device and determine online status.

2. In the Destination Port field enter the port on the remote device that is to receive the TCP keepalive request. The valid entries are from 1 to 65535. If you do not specify a destination port, the GSS uses the globally configured value.

3. If you enabled the VIP Address check box, specify one of the TCP keepalive connection termination methods:

• Default—Always use the globally defined TCP keepalive connection method.

•Reset—The GSS immediately terminates the TCP connection by using a hard reset.

•Graceful—The GSS initiates the graceful closing of a TCP connection by using the standard three-way connection termination method.

4. If the TCP global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section:

•In the Number of Retries field, specify the number of times that the GSS retransmits a TCP packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries, you increase the detection time. Reducing the number of retries has the reverse effect. The valid entries are from 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value.

Note When using the Graceful termination sequence, there are two packets that require acknowledgement: SYN and FIN.

•In the Number of Successful Probes field, specify the number of consecutive successful TCP keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The valid entries are from 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value.

Note For more information on keepalive detection time, refer to the the "Keepalives" section in Chapter 1, Introducing the Global Site Selector.

5. Click the Submit button to save your TCP keepalive VIP answer and return to the Answers list page.

Configuring Shared HTTP HEAD Keepalive VIP Answer Settings

To define the shared HTTP HEAD keepalive for your VIP answer, perform the following procedure. Refer to Figure 6-6 when performing this procedure.

Figure 6-6 Answer Details Page—HTTP HEAD KeepAlive VIP Answer

1. If necessary, uncheck the VIP Address check box and select an HTTP-type shared keepalive from the Shared HTTP HEAD keepalive drop-down list. The VIP Address check box is automatically checked to instruct the GSS to send a TCP-format HTTP HEAD request to the web server at an address you specified and determine online status.

2. In the Destination Port field, enter the port on the remote device that receives the HTTP HEAD-type keepalive request from the GSS. The valid entries are from 1 to 65535. If you do not specify a destination port, the GSS uses the globally configured value.

3. In the Host Tag field, enter an optional domain name that is sent to the VIP as part of the HTTP HEAD query in the Host tag field. This tag allows an SLB to resolve the keepalive request to a particular website even when multiple sites are represented by the same VIP.

4. In the Path field, enter the path that is relative to the server website being queried in the HTTP HEAD request. If you do not specify a default path, the GSS uses the globally configured value. For example: /company/owner

5. If you enabled the VIP Address check box, specify one of the HTTP HEAD keepalive connection termination methods:

• Default—Always use the globally defined HTTP HEAD keepalive connection method.

•Reset—The GSS immediately terminates the TCP-formatted HTTP HEAD connection by using a hard reset.

•Graceful—The GSS initiates the graceful closing of a TCP-formatted HTTP HEAD connection by using the standard three-way connection termination method.

6. If the HTTP HEAD global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section:

•In the Number of Retries field, specify the number of times that the GSS retransmits a TCP packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries, you increase the detection time. Reducing the number of retries has the reverse effect. The valid entries are from 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value.

Note When using the Graceful termination sequence, there are three packets that require acknowledgement: SYN, HEAD, and FIN.

•In the Number of Successful Probes field, specify the number of consecutive successful HTTP HEAD keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The valid entries are from 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value.

Note For more information on keepalive detection time, refer to the "Keepalives" section in Chapter 1, Introducing the Global Site Selector.

7. Click the Submit button to save your HTTP HEAD keepalive VIP answer and return to the Answers list page.

Configuring Shared KAL-AP Keepalive VIP Answer Settings

To define the shared KAL-AP keepalive for your VIP answer, perform the following procedure. Refer to Figure 6-7 when performing this procedure.

Figure 6-7 Answer Details Page—KAL-AP Keepalive VIP Answer

1. From the KAL-AP Type drop-down list, select one of the following formats of the KAL-AP keepalive query:

• KAL-AP By Tag—Embeds an alphanumeric tag associated with the VIP in the KAL-AP request. The tag value is used to match the correct shared keepalive VIP, thus avoiding confusion that can be caused when probing for the status of a VIP that is located behind a firewall network address translation (NAT).

• KAL-AP By VIP—Embeds the keepalive VIP address in the KAL-AP request. The KAL-AP queries the keepalive address to determine the online status.

2. If you chose KAL-AP By VIP, select the appropriate KAL-AP type keepalive from the Shared KAL-AP Keepalive drop-down list.

3. If you chose KAL-AP By Tag, select the appropriate KAL-AP type keepalive from the Shared KAL-AP Keepalive drop-down list, then enter a unique alphanumeric value in the Tag field. This value is used as a "key" by the CSS or GSSM that matches the KAL-AP request with the appropriate VIP.

4. Click the Submit button to save your KAL-AP keepalive VIP answer and return to the Answers list page.

Creating 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.

Note Once an answer is created, you cannot modify the answer type (for example, from CRA to VIP).

To configure a CRA-type answer type:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1).

3. Click the Create Answer icon. The Creating New Answer details page appears (see Figure 6-2).

4. In the Type selection field, click the CRA option button. The CRA Answer section appears in the details page (Figure 6-8).

Figure 6-8 Creating New Answer—CRA Answer

5. In the Name field, enter a name for the CRA-type answer. Specifying a name for an answer is an optional step.

6. In the Location drop-down list, select a location for the answer. Specifying a location for an answer is an optional step. For details about creating a location, refer to Chapter 2, Configuring Resources.

7. In the CRA Address field, enter the interface or circuit address of the CRA.

8. If you want the GSS to perform keepalive checks on the CRA-type answer, click the Perform KeepAlive Check check box. Uncheck the Perform KeepAlive option if a static one-way delay value is used.

9. If you require a one-way delay time, enter a value, in milliseconds, in the One Way Delay field. This value is used by the GSS to calculate a static round-trip time (RTT), with the one-way delay constituting one-half of the round-trip time that is used for all DNS races involving this answer.

10. Click Submit to create your new CRA-type answer and return to the Answers list page.

Creating 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.

Note Once an answer is created, you cannot modify the answer type (for example, from name server to VIP).

To configure a name server-type answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1).

3. Click the Create Answer icon. The Creating New Answer details page appears (see Figure 6-2).

4. In the Type field, click the Name Server option button. The Name Server Answer section appears in the Creating New Answer details page (Figure 6-9).

Figure 6-9 Creating New Answer—Name Server Answer

5. In the Name field, enter a name for the name server-type answer. Specifying a name for an answer is an optional step.

6. From the Location drop-down list, select a GSS location to which the answer corresponds. Specifying a location for an answer is an optional step. For details about creating a location, refer to Chapter 2, Configuring Resources.

7. In the Name Server Address field, enter the IP address of the name server that the GSS is to forward its requests.

8. If you want the GSS to perform keepalive checks on the specified Name Server, click the Perform KeepAlive Check check box. The GSS queries the specified name server address to determine the online status.

9. If you wish to have the GSS query the name server for a specific domain in determining the online status, enter the domain name in the KeepAlive Query Domain field.

If no domain is specified, the GSS queries the default query domain. For instructions on configuring the default query domain, see Chapter 5, Configuring Keepalives.

10. Click Submit to create your new name server-type answer and return to the Answers list page.

Modifying an Answer

Once you have configured your answers, they can be modified at any time. However, once an answer is created, you cannot modify the answer type (for example, from VIP to CRA).

To modify an existing answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears.

3. Click the Modify Answer icon located to the left of the answer that you want to modify. The Modifying Answer details page appears (Figure 6-10).

Figure 6-10 Modifying Answer Details Page

4. Use the fields provided to modify the answer configuration.

5. Click Submit to save your configuration changes and return to the Answers list page.

Suspending an Answer

To temporarily stop the GSS from using an active answer, use the Suspend Answer icon on the Modifying Answer details page to prevent that answer from being used by any of the currently configured DNS rules.

Note You can suspend multiple answers associated with an answer group from the Modify Answer Group details page. See the "Suspending or Reactivating Answers in an Answer Group" section for details.

To suspend an answer from the Modify Answer details page:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1).

3. Click the Modify Answer icon located to the left of the answer you want to suspend. The Modifying Answer details page appears (see Figure 6-10).

4. Click the Suspend Answer icon in the upper right corner of the page to suspend an answer.

5. Click OK to confirm your decision and return to the Answers list screen. The modified answer has a status of "Suspended".

To reactivate a suspended answer, use the activate feature (see the "Reactivating an Answer" section).

Reactivating an Answer

To reactivate a suspended answer from the Modify Answer details page:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1).

3. Click the Modify Answer icon located to the left of the answer that you want to activate. All suspended answers have a status of "Suspended" in the list. The Modifying Answer details page appears (see Figure 6-10).

4. Click the Activate Answer icon in the upper right corner of the page to reactivate an answer.

5. Click OK to confirm your decision and return to the Answers list screen. The modified answer has a status of "Active".

Suspending or Reactivating All Answers in a Location

Answers can be grouped and managed 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 for the purposes of software upgrades or regular maintenance.

The GSS automatically detects and routes requests around suspended answers.

Note Suspending all answers in a location overrides the active or suspended state of an individual answer.

To suspend or reactivate answers based on their location:

1. From the primary GSSM GUI, click the Resources tab.

2. Click the Locations navigation link. The Locations list page appears.

3. Click the Modify Location icon located to the left of the location that includes answers that you want to suspend or reactivate. The Modifying Location details page appears.

4. Perform one of the following:

•To suspend answers associated with this location, click the Suspend All Answers in This Location icon.

•To reactivate suspended answers associated with this location, click the Activate All Answers in This Location icon.

5. Confirm your decision to suspend or activate the answers associated with this location.

6. Click OK to confirm your decision and return to the Locations list page.

Deleting an Answer

If you have created an answer but wish to delete it from the GSS, use the delete feature on the primary GSSM GUI to remove that answer.

Caution Deletions of any kind cannot be undone in the primary GSSM. If you might want to use the deleted data at a later point in time, we recommend performing a database backup of your GSSM. Refer to the Global Site Selector Administration Guide for details.

To delete an answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1).

3. Click the Modify Answer icon located to the left of the answer you want to remove. The Modifying Answer details page appears (see Figure 6-10).

4. Click the Delete Answer icon in the upper right corner of the page. The GSS software prompts you to confirm your decision to delete the answer.

5. Click OK to confirm your decision and return to the Answers list page.

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 a particular balance method that is used to resolve the request.

•For a VIP answer group type, the GSS selects one or more VIPs using the balance method specified in the DNS rule.

•For a CRA answer group type, all CRAs in the answer group are queried and then "race" to respond first to the D-proxy with their IP address.

•For a name server answer group type, the GSS selects a name server using the balance method specified in the DNS rule and forwards the client's request to that name server.

A DNS rule can have up to 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.

This section includes the following procedures:

•Creating an Answer Group

•Modifying an Answer Group

•Suspending or Reactivating Answers in an Answer Group

•Suspending or Reactivating All Answers in an Answer Group Associated with an Owner

•Deleting an Answer Group

Creating an Answer Group

To create an answer group:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answer Groups navigation link. The Answer Groups list page appears (Figure 6-11).

Figure 6-11 Answer Group List Page

3. Click the Create Answer Group icon. The Creating New Answer Group details page appears (Figure 6-12).

Figure 6-12 Creating New Answer Group Details Page—General Configuration

4. In the General Configuration details page (General Configuration navigation link), perform the following:

• In the Name field, enter a name for the new answer group. The answer group name cannot contain spaces.

• From the Type drop-down list, choose one of the following three options:

Name Server—The answer group consists of configured name servers.

CRA—The answer group consists of content routing agents (CRAs) for use with the boomerang server component of the GSS.

VIP—The answer group consists of virtual IPs controlled by an SLB device such as a CSS or CSM.

5. From the Owner drop-down list, select the GSS owner with which the answer group will be associated. For details about creating an owner, refer to Chapter 2, Configuring Resources.

6. In the Comments text area, enter a description or other instructions regarding the new answer group.

7. Click the Add Answers navigation link to access the Add Answers section of the page (Figure 6-13). Perform the following:

a. Click the check box corresponding to each answer that you wish to add to the answer group. If the list of answers on your GSS network spans more than one page, select the answers from only the first page of answers and proceed to the next step.

b. Click the Add Selected button. The GSS adds the selected answers to the answer group. Answers can belong to more than one answer group simultaneously.

c. Repeat steps a and b if your answers span multiple pages.

Note If an answer is added to multiple answer groups, when you view the hit count of answers from either the Answer Status list page or the show statistics dns CLI command output, the number of hits provided represents the aggregate number of hits for that answer across all answer groups.

Figure 6-13 Creating New Answer Group Details Page—Add Answers

8. Click the General Configuration navigation link to return to the General Configuration section. The newly added answers appear in the Current Members section (Figure 6-14). There are different configuration options depending on the type of answer group.

Figure 6-14 Creating New Answer Group Details Page—Current Members

9. Perform one of the following:

• If configuring CRA, no configuration parameters are required.

• If configuring a Name Server type answer group, assign an order and weight to each Answer in the answer group using the field and drop-down list provided.

• If configuring a VIP type answer group, assign an order, load threshold (LT), and weight to each answer in the answer group using the fields and drop-down lists provided.

Note Load thresholds, which allow the GSS to make routing decisions based on how heavily a particular resource is being tasked, can only be assigned to VIP answers using a KAL-AP keepalive.

For more information on the order, weight, and load threshold settings, refer to the "Balance Methods" section in Chapter 1, Introducing the Global Site Selector.

10. Click the Submit button to save your answer group and return to the Answer Group list page.

Modifying an Answer Group

Once you create your answer groups, use the primary GSSM GUI 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:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answer Groups navigation link. The Answer Groups list page appears (see Figure 6-11).

3. Click the Modify Answer Group icon located to the left of the answer group that you want to modify. The Modify Answer Group details page appears.

4. In the General Configuration details page (General Configuration navigation link), use the fields provided to modify the name, owner, or comments for the answer group.

5. Click the Add Answers navigation link. Click the check box corresponding to each answer that you wish to add to the answer group. If the list of answers on your GSS network spans more than one page, select the answers from only the first page of answers, then click Add Selected, before proceeding to another page of answers.

6. To remove answers from the answer group, click the Remove Answers navigation link. The Remove Answers section of the page appears (Figure 6-15). Click the check box accompanying each answer that you wish to remove from the list, then click the Remove Selected button. The GSS removes the selected answers from the page.

Figure 6-15 Modifying Answer Group—Remove Answers

7. Review your updated answer group under the Current Members section of the General Configuration details page (see Figure 6-14).

8. Click the Submit button to save your changes and return to the Answer Groups Lists page.

Suspending or Reactivating Answers in an Answer Group

To temporarily stop the GSS from directing requests to it, use the Suspend Answers icon on the primary GSSM GUI. The Suspend Answers function temporarily suspends the answers that make up that group and prevents the answer group from being used by any of the currently configured DNS rules. You can suspend all answers associated with the answer group or suspend individual answers in the group.

Use the Activate Answers icon to reactivate the answers in the answer group.

Note Suspending the answers in one answer group also affects any other answer groups to which those answers belong.

To suspend or reactivate answers in an answer group:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answer Groups navigation link. The Answer Groups list page appears (see Figure 6-11).

3. Click the Modify Answer Group icon located to the left of the answer group that you want to suspend or reactivate. The Modifying Answer Group details page appears (Figure 6-16).

Figure 6-16 Modifying Answer Group—Suspend Answers Icon

4. To suspend answers in the answer group, perform one of the following:

•To suspend all answers in the answer group, click the Suspend Answers icon in the upper-right corner of the page.

•To suspend individual answers associated with the answer group, click the Suspend Answer icon to the right of the answer in the General Configuration details page.

5. To reactivate suspended answers in the answer group, perform one of the following:

•To reactivate all answers in the answer group, click the Activate Answers icon in the upper-right corner of the page.

•To reactivate individual answers associated with the answer group, click the Activate Answer icon to the right of the answer in the General Configuration details page.

6. Click OK to confirm your decision and return to the Answer Groups list page.

7. To view the status of the suspended or activated answers, refer to Chapter 10, Monitoring GSS Global Server Load-Balancing Operation.

Suspending or Reactivating All Answers in an Answer Group Associated with an Owner

Answers added to answer groups can be grouped and managed according to GSS owner. Using a GSS owner to manage your answer groups simplifies the process to quickly suspend or activate related answers.

To suspend or reactivate all answers in answer groups associated with a GSS owner:

1. From the primary GSSM GUI, click the Resources tab.

2. Click the Owners navigation link. The Owners list page appears (Figure 6-17).

Figure 6-17 Owners List Page

3. Click the Modify Owner icon located to the left of the answer group that you want to suspend or reactivate. The Modifying Owner details page appears (Figure 6-18).

Figure 6-18 Modifying Owners Details Page

4. Perform one of the following:

•To suspend all answers in all answer groups associated with this owner, click the Suspend All Answers in All Groups for This Owner icon in the upper-right corner of the details page.

•To reactivate all suspended answers associated with this owner, click the Activate All Answers in All Groups for This Owner icon in the upper-right corner of the details page.

5. Click OK to confirm your decision to suspend or activate the answers. You return to the Owner list page.

Deleting an Answer Group

To delete an answer group from the GSS, use the Delete Answer Group icon on the primary GSSM GUI to remove that answer group. 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. Refer to 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.

Caution Deletions of any kind cannot be undone in the primary GSSM. If you might use the deleted data at a later point in time, we recommend performing a database backup of your GSSM. Refer to the Cisco Global Site Selector Administration Guide for details.

To delete an answer group:

1. From the primary GSSM GUI, click DNS Rules tab.

2. Click the Answer Groups navigation link. The Answer Groups list page appears.

3. Click the Modify Answer Group icon located to the left of the answer group that you want to remove. The Modifying Answer Group details page appears (see Figure 6-16).

4. Click the Delete Answer Group icon in the upper right corner of the page. The GSS software prompts you to confirm your decision to delete the answer group.

5. Click OK to confirm your decision and return to the Answer Groups list page.

Where to Go Next

Chapter 7, Building and Modifying DNS Rules, describes constructing the DNS rules that govern all global server load balancing on your GSS network.

	Cisco GSS Global Server Load-Balancing Configuration Guide (Software Version 1.2)
	Configuring Answers and Answer Groups
Cisco GSS Global Server Load-Balancing Configuration Guide (Software Version 1.2) Index Preface Introducing the Global Site Selector Configuring Resources Configuring Source Address Lists Configuring Domain Lists Configuring Keepalives Configuring Answers and Answer Groups Building and Modifying DNS Rules Configuring DNS Sticky Configuring Network Proximity Monitoring GSS Global Server Load-Balancing Operation Primary GSSM Global Server Load-Balancing Error Messages Glossary	Download this chapter Configuring Answers and Answer Groups Download the complete book Cisco Global Site Selector Global Server Load-Balancing Configuration Guide Book-Length PDF, Software Version 1.2 (PDF - 7 MB) Table Of Contents Configuring Answers and Answer Groups Configuring and Modifying Answers Creating a VIP-Type Answer Configuring Shared ICMP Keepalive VIP Answer Settings Configuring Shared TCP Keepalive VIP Answer Settings Configuring Shared HTTP HEAD Keepalive VIP Answer Settings Configuring Shared KAL-AP Keepalive VIP Answer Settings Creating a CRA-Type Answer Creating a Name Server-Type Answer Modifying an Answer Suspending an Answer Reactivating an Answer Suspending or Reactivating All Answers in a Location Deleting an Answer Configuring and Modifying Answer Groups Creating an Answer Group Modifying an Answer Group Suspending or Reactivating Answers in an Answer Group Suspending or Reactivating All Answers in an Answer Group Associated with an Owner Deleting an Answer Group Where to Go Next 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: •Configuring and Modifying Answers •Configuring and Modifying Answer Groups •Where to Go Next Configuring and Modifying Answers In a GSS network, the term answers 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 and that can provide the requesting client D-proxy with the address of a valid host to serve their request. GSS answers include the following: •VIP—Virtual IP (VIP) addresses associated with an SLB such as the Cisco CSS, Cisco CSM, Cisco IOS-compliant SLB, LocalDirector, a web server, cache, or other geographically dispersed SLBs in a global network deployment. •Name Server—A configured DNS name server on your network that can answer queries that the GSS cannot resolve. •CRA—Content routing agents that use a resolution process called DNS race to send identical and simultaneous responses back to a user's D-proxy. The GSS groups answers together as resource pools, also referred to as answer groups. From the available answer groups, the GSS can use up to 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, further intelligence can be applied to DNS queries by the GSS 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. This section includes the following procedures: •Creating a VIP-Type Answer •Creating a CRA-Type Answer •Creating a Name Server-Type Answer •Modifying an Answer •Suspending an Answer •Reactivating an Answer •Suspending or Reactivating All Answers in a Location •Deleting an Answer Creating a VIP-Type Answer The VIP-type answer refers to a virtual IP address (VIP) associated with an SLB device such as a Cisco CSS or CSM. When the GSS receives requests for content that is managed by an SLB, the GSS returns an A-record containing the VIP of the SLB that manages the content. When configuring a VIP-type answer you have the option to configure one of a variety of different keepalive types to test for that answer. For a KAL-AP keepalive, configure shared keepalive before you configure your answer. Refer to Chapter 5, Configuring Keepalives for more information on creating shared keepalives. Note Once an answer is created, you cannot modify the answer type (for example, from VIP to CRA). To configure a VIP-type answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (Figure 6-1). Figure 6-1 Answers List Page 3. Click the Create Answer icon. The Creating New Answer detail page appears (Figure 6-2). Figure 6-2 Creating New Answer Details Page 4. In the Type field, click the VIP option button. The VIP Answer section appears in the details page (Figure 6-3). Figure 6-3 Creating New Answer—VIP Details Page 5. In the Name field, enter a name for the VIP-type answer that you are creating. Specifying a name for an answer is an optional step. 6. From the Location drop-down list, select a GSS location that corresponds to the answer. Specifying a location for an answer is an optional step unless you are assigning a location that is associated with a proximity zone to the answer. For details about creating a location, refer to Chapter 2, Configuring Resources. 7. In the VIP address field, enter the VIP address to which the GSS will forward requests. 8. Choose from one of these five keepalive types for your VIP answer: • None—Does not send keepalive queries to the VIP. The GSS assumes that the VIP is always alive. • ICMP—Sends an ICMP echo message (ping) to the specified address. The GSS determines the online status by the response received from the device, indicating simple connectivity to the network. • TCP—Sends a TCP handshake to the specified IP address 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. • HTTP HEAD—Sends a TCP-format HTTP HEAD request to an origin web server at a specified address. 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. • KAL-AP—Sends a detailed query to the Cisco CSS or CSM to extract 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 following sections describe how to configure the properties for the individual VIP keepalives. The default values used for each of the VIP keepalives are determined by the values specified in the Global Keepalive Properties details page. •Configuring Shared ICMP Keepalive VIP Answer Settings •Configuring Shared TCP Keepalive VIP Answer Settings •Configuring Shared HTTP HEAD Keepalive VIP Answer Settings •Configuring Shared KAL-AP Keepalive VIP Answer Settings Configuring Shared ICMP Keepalive VIP Answer Settings To define the shared ICMP keepalive for your VIP answer, perform the following procedure. Refer to Figure 6-4 when performing this procedure. Figure 6-4 Answer Details Page—ICMP KeepAlive VIP Answer 1. If necessary, uncheck the VIP Address check box and select an ICMP-type shared keepalive from the Shared ICMP Keepalive drop-down list. The VIP Address check box is automatically checked to instruct the GSS to send an ICMP echo message (ping) to the VIP address of the remote device and determine the online status. 2. If the ICMP global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section: •In the Number of Retries field, specify the number of times the GSS retransmits an ICMP echo request packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries you increase the detection time. Reducing the number of retries has the reverse effect. The valid entries are from 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value. •In the Number of Successful Probes field, specify the number of consecutive successful ICMP keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The valid entries are from 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value. Note For more information on keepalive detection time, refer to Chapter 1, Introducing the Global Site Selector, the "Keepalives" section. 3. Click the Submit button to save your ICMP keepalive VIP answer and return to the Answers list page. Configuring Shared TCP Keepalive VIP Answer Settings To define the shared TCP keepalive for your VIP answer, perform the following procedure. Refer to Figure 6-5 when performing this procedure. Figure 6-5 Answer Details Page—TCP KeepAlive VIP Answer 1. If necessary, uncheck the VIP Address check box and choose a TCP-type shared keepalive from the Shared TCP Keepalive drop-down list. The VIP Address check box is automatically checked to instruct the GSS to send a TCP keepalive to the VIP address of the remote device and determine online status. 2. In the Destination Port field enter the port on the remote device that is to receive the TCP keepalive request. The valid entries are from 1 to 65535. If you do not specify a destination port, the GSS uses the globally configured value. 3. If you enabled the VIP Address check box, specify one of the TCP keepalive connection termination methods: • Default—Always use the globally defined TCP keepalive connection method. •Reset—The GSS immediately terminates the TCP connection by using a hard reset. •Graceful—The GSS initiates the graceful closing of a TCP connection by using the standard three-way connection termination method. 4. If the TCP global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section: •In the Number of Retries field, specify the number of times that the GSS retransmits a TCP packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries, you increase the detection time. Reducing the number of retries has the reverse effect. The valid entries are from 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value. Note When using the Graceful termination sequence, there are two packets that require acknowledgement: SYN and FIN. •In the Number of Successful Probes field, specify the number of consecutive successful TCP keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The valid entries are from 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value. Note For more information on keepalive detection time, refer to the the "Keepalives" section in Chapter 1, Introducing the Global Site Selector. 5. Click the Submit button to save your TCP keepalive VIP answer and return to the Answers list page. Configuring Shared HTTP HEAD Keepalive VIP Answer Settings To define the shared HTTP HEAD keepalive for your VIP answer, perform the following procedure. Refer to Figure 6-6 when performing this procedure. Figure 6-6 Answer Details Page—HTTP HEAD KeepAlive VIP Answer 1. If necessary, uncheck the VIP Address check box and select an HTTP-type shared keepalive from the Shared HTTP HEAD keepalive drop-down list. The VIP Address check box is automatically checked to instruct the GSS to send a TCP-format HTTP HEAD request to the web server at an address you specified and determine online status. 2. In the Destination Port field, enter the port on the remote device that receives the HTTP HEAD-type keepalive request from the GSS. The valid entries are from 1 to 65535. If you do not specify a destination port, the GSS uses the globally configured value. 3. In the Host Tag field, enter an optional domain name that is sent to the VIP as part of the HTTP HEAD query in the Host tag field. This tag allows an SLB to resolve the keepalive request to a particular website even when multiple sites are represented by the same VIP. 4. In the Path field, enter the path that is relative to the server website being queried in the HTTP HEAD request. If you do not specify a default path, the GSS uses the globally configured value. For example: `/company/owner` 5. If you enabled the VIP Address check box, specify one of the HTTP HEAD keepalive connection termination methods: • Default—Always use the globally defined HTTP HEAD keepalive connection method. •Reset—The GSS immediately terminates the TCP-formatted HTTP HEAD connection by using a hard reset. •Graceful—The GSS initiates the graceful closing of a TCP-formatted HTTP HEAD connection by using the standard three-way connection termination method. 6. If the HTTP HEAD global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section: •In the Number of Retries field, specify the number of times that the GSS retransmits a TCP packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries, you increase the detection time. Reducing the number of retries has the reverse effect. The valid entries are from 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value. Note When using the Graceful termination sequence, there are three packets that require acknowledgement: SYN, HEAD, and FIN. •In the Number of Successful Probes field, specify the number of consecutive successful HTTP HEAD keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The valid entries are from 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value. Note For more information on keepalive detection time, refer to the "Keepalives" section in Chapter 1, Introducing the Global Site Selector. 7. Click the Submit button to save your HTTP HEAD keepalive VIP answer and return to the Answers list page. Configuring Shared KAL-AP Keepalive VIP Answer Settings To define the shared KAL-AP keepalive for your VIP answer, perform the following procedure. Refer to Figure 6-7 when performing this procedure. Figure 6-7 Answer Details Page—KAL-AP Keepalive VIP Answer 1. From the KAL-AP Type drop-down list, select one of the following formats of the KAL-AP keepalive query: • KAL-AP By Tag—Embeds an alphanumeric tag associated with the VIP in the KAL-AP request. The tag value is used to match the correct shared keepalive VIP, thus avoiding confusion that can be caused when probing for the status of a VIP that is located behind a firewall network address translation (NAT). • KAL-AP By VIP—Embeds the keepalive VIP address in the KAL-AP request. The KAL-AP queries the keepalive address to determine the online status. 2. If you chose KAL-AP By VIP, select the appropriate KAL-AP type keepalive from the Shared KAL-AP Keepalive drop-down list. 3. If you chose KAL-AP By Tag, select the appropriate KAL-AP type keepalive from the Shared KAL-AP Keepalive drop-down list, then enter a unique alphanumeric value in the Tag field. This value is used as a "key" by the CSS or GSSM that matches the KAL-AP request with the appropriate VIP. 4. Click the Submit button to save your KAL-AP keepalive VIP answer and return to the Answers list page. Creating 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. Note Once an answer is created, you cannot modify the answer type (for example, from CRA to VIP). To configure a CRA-type answer type: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1). 3. Click the Create Answer icon. The Creating New Answer details page appears (see Figure 6-2). 4. In the Type selection field, click the CRA option button. The CRA Answer section appears in the details page (Figure 6-8). Figure 6-8 Creating New Answer—CRA Answer 5. In the Name field, enter a name for the CRA-type answer. Specifying a name for an answer is an optional step. 6. In the Location drop-down list, select a location for the answer. Specifying a location for an answer is an optional step. For details about creating a location, refer to Chapter 2, Configuring Resources. 7. In the CRA Address field, enter the interface or circuit address of the CRA. 8. If you want the GSS to perform keepalive checks on the CRA-type answer, click the Perform KeepAlive Check check box. Uncheck the Perform KeepAlive option if a static one-way delay value is used. 9. If you require a one-way delay time, enter a value, in milliseconds, in the One Way Delay field. This value is used by the GSS to calculate a static round-trip time (RTT), with the one-way delay constituting one-half of the round-trip time that is used for all DNS races involving this answer. 10. Click Submit to create your new CRA-type answer and return to the Answers list page. Creating 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. Note Once an answer is created, you cannot modify the answer type (for example, from name server to VIP). To configure a name server-type answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1). 3. Click the Create Answer icon. The Creating New Answer details page appears (see Figure 6-2). 4. In the Type field, click the Name Server option button. The Name Server Answer section appears in the Creating New Answer details page (Figure 6-9). Figure 6-9 Creating New Answer—Name Server Answer 5. In the Name field, enter a name for the name server-type answer. Specifying a name for an answer is an optional step. 6. From the Location drop-down list, select a GSS location to which the answer corresponds. Specifying a location for an answer is an optional step. For details about creating a location, refer to Chapter 2, Configuring Resources. 7. In the Name Server Address field, enter the IP address of the name server that the GSS is to forward its requests. 8. If you want the GSS to perform keepalive checks on the specified Name Server, click the Perform KeepAlive Check check box. The GSS queries the specified name server address to determine the online status. 9. If you wish to have the GSS query the name server for a specific domain in determining the online status, enter the domain name in the KeepAlive Query Domain field. If no domain is specified, the GSS queries the default query domain. For instructions on configuring the default query domain, see Chapter 5, Configuring Keepalives. 10. Click Submit to create your new name server-type answer and return to the Answers list page. Modifying an Answer Once you have configured your answers, they can be modified at any time. However, once an answer is created, you cannot modify the answer type (for example, from VIP to CRA). To modify an existing answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears. 3. Click the Modify Answer icon located to the left of the answer that you want to modify. The Modifying Answer details page appears (Figure 6-10). Figure 6-10 Modifying Answer Details Page 4. Use the fields provided to modify the answer configuration. 5. Click Submit to save your configuration changes and return to the Answers list page. Suspending an Answer To temporarily stop the GSS from using an active answer, use the Suspend Answer icon on the Modifying Answer details page to prevent that answer from being used by any of the currently configured DNS rules. Note You can suspend multiple answers associated with an answer group from the Modify Answer Group details page. See the "Suspending or Reactivating Answers in an Answer Group" section for details. To suspend an answer from the Modify Answer details page: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1). 3. Click the Modify Answer icon located to the left of the answer you want to suspend. The Modifying Answer details page appears (see Figure 6-10). 4. Click the Suspend Answer icon in the upper right corner of the page to suspend an answer. 5. Click OK to confirm your decision and return to the Answers list screen. The modified answer has a status of "Suspended". To reactivate a suspended answer, use the activate feature (see the "Reactivating an Answer" section). Reactivating an Answer To reactivate a suspended answer from the Modify Answer details page: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1). 3. Click the Modify Answer icon located to the left of the answer that you want to activate. All suspended answers have a status of "Suspended" in the list. The Modifying Answer details page appears (see Figure 6-10). 4. Click the Activate Answer icon in the upper right corner of the page to reactivate an answer. 5. Click OK to confirm your decision and return to the Answers list screen. The modified answer has a status of "Active". Suspending or Reactivating All Answers in a Location Answers can be grouped and managed 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 for the purposes of software upgrades or regular maintenance. The GSS automatically detects and routes requests around suspended answers. Note Suspending all answers in a location overrides the active or suspended state of an individual answer. To suspend or reactivate answers based on their location: 1. From the primary GSSM GUI, click the Resources tab. 2. Click the Locations navigation link. The Locations list page appears. 3. Click the Modify Location icon located to the left of the location that includes answers that you want to suspend or reactivate. The Modifying Location details page appears. 4. Perform one of the following: •To suspend answers associated with this location, click the Suspend All Answers in This Location icon. •To reactivate suspended answers associated with this location, click the Activate All Answers in This Location icon. 5. Confirm your decision to suspend or activate the answers associated with this location. 6. Click OK to confirm your decision and return to the Locations list page. Deleting an Answer If you have created an answer but wish to delete it from the GSS, use the delete feature on the primary GSSM GUI to remove that answer. Caution Deletions of any kind cannot be undone in the primary GSSM. If you might want to use the deleted data at a later point in time, we recommend performing a database backup of your GSSM. Refer to the Global Site Selector Administration Guide for details. To delete an answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 6-1). 3. Click the Modify Answer icon located to the left of the answer you want to remove. The Modifying Answer details page appears (see Figure 6-10). 4. Click the Delete Answer icon in the upper right corner of the page. The GSS software prompts you to confirm your decision to delete the answer. 5. Click OK to confirm your decision and return to the Answers list page. 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 a particular balance method that is used to resolve the request. •For a VIP answer group type, the GSS selects one or more VIPs using the balance method specified in the DNS rule. •For a CRA answer group type, all CRAs in the answer group are queried and then "race" to respond first to the D-proxy with their IP address. •For a name server answer group type, the GSS selects a name server using the balance method specified in the DNS rule and forwards the client's request to that name server. A DNS rule can have up to 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. This section includes the following procedures: •Creating an Answer Group •Modifying an Answer Group •Suspending or Reactivating Answers in an Answer Group •Suspending or Reactivating All Answers in an Answer Group Associated with an Owner •Deleting an Answer Group Creating an Answer Group To create an answer group: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answer Groups navigation link. The Answer Groups list page appears (Figure 6-11). Figure 6-11 Answer Group List Page 3. Click the Create Answer Group icon. The Creating New Answer Group details page appears (Figure 6-12). Figure 6-12 Creating New Answer Group Details Page—General Configuration 4. In the General Configuration details page (General Configuration navigation link), perform the following: • In the Name field, enter a name for the new answer group. The answer group name cannot contain spaces. • From the Type drop-down list, choose one of the following three options: Name Server—The answer group consists of configured name servers. CRA—The answer group consists of content routing agents (CRAs) for use with the boomerang server component of the GSS. VIP—The answer group consists of virtual IPs controlled by an SLB device such as a CSS or CSM. 5. From the Owner drop-down list, select the GSS owner with which the answer group will be associated. For details about creating an owner, refer to Chapter 2, Configuring Resources. 6. In the Comments text area, enter a description or other instructions regarding the new answer group. 7. Click the Add Answers navigation link to access the Add Answers section of the page (Figure 6-13). Perform the following: a. Click the check box corresponding to each answer that you wish to add to the answer group. If the list of answers on your GSS network spans more than one page, select the answers from only the first page of answers and proceed to the next step. b. Click the Add Selected button. The GSS adds the selected answers to the answer group. Answers can belong to more than one answer group simultaneously. c. Repeat steps a and b if your answers span multiple pages. Note If an answer is added to multiple answer groups, when you view the hit count of answers from either the Answer Status list page or the show statistics dns CLI command output, the number of hits provided represents the aggregate number of hits for that answer across all answer groups. Figure 6-13 Creating New Answer Group Details Page—Add Answers 8. Click the General Configuration navigation link to return to the General Configuration section. The newly added answers appear in the Current Members section (Figure 6-14). There are different configuration options depending on the type of answer group. Figure 6-14 Creating New Answer Group Details Page—Current Members 9. Perform one of the following: • If configuring CRA, no configuration parameters are required. • If configuring a Name Server type answer group, assign an order and weight to each Answer in the answer group using the field and drop-down list provided. • If configuring a VIP type answer group, assign an order, load threshold (LT), and weight to each answer in the answer group using the fields and drop-down lists provided. Note Load thresholds, which allow the GSS to make routing decisions based on how heavily a particular resource is being tasked, can only be assigned to VIP answers using a KAL-AP keepalive. For more information on the order, weight, and load threshold settings, refer to the "Balance Methods" section in Chapter 1, Introducing the Global Site Selector. 10. Click the Submit button to save your answer group and return to the Answer Group list page. Modifying an Answer Group Once you create your answer groups, use the primary GSSM GUI 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: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answer Groups navigation link. The Answer Groups list page appears (see Figure 6-11). 3. Click the Modify Answer Group icon located to the left of the answer group that you want to modify. The Modify Answer Group details page appears. 4. In the General Configuration details page (General Configuration navigation link), use the fields provided to modify the name, owner, or comments for the answer group. 5. Click the Add Answers navigation link. Click the check box corresponding to each answer that you wish to add to the answer group. If the list of answers on your GSS network spans more than one page, select the answers from only the first page of answers, then click Add Selected, before proceeding to another page of answers. 6. To remove answers from the answer group, click the Remove Answers navigation link. The Remove Answers section of the page appears (Figure 6-15). Click the check box accompanying each answer that you wish to remove from the list, then click the Remove Selected button. The GSS removes the selected answers from the page. Figure 6-15 Modifying Answer Group—Remove Answers 7. Review your updated answer group under the Current Members section of the General Configuration details page (see Figure 6-14). 8. Click the Submit button to save your changes and return to the Answer Groups Lists page. Suspending or Reactivating Answers in an Answer Group To temporarily stop the GSS from directing requests to it, use the Suspend Answers icon on the primary GSSM GUI. The Suspend Answers function temporarily suspends the answers that make up that group and prevents the answer group from being used by any of the currently configured DNS rules. You can suspend all answers associated with the answer group or suspend individual answers in the group. Use the Activate Answers icon to reactivate the answers in the answer group. Note Suspending the answers in one answer group also affects any other answer groups to which those answers belong. To suspend or reactivate answers in an answer group: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answer Groups navigation link. The Answer Groups list page appears (see Figure 6-11). 3. Click the Modify Answer Group icon located to the left of the answer group that you want to suspend or reactivate. The Modifying Answer Group details page appears (Figure 6-16). Figure 6-16 Modifying Answer Group—Suspend Answers Icon 4. To suspend answers in the answer group, perform one of the following: •To suspend all answers in the answer group, click the Suspend Answers icon in the upper-right corner of the page. •To suspend individual answers associated with the answer group, click the Suspend Answer icon to the right of the answer in the General Configuration details page. 5. To reactivate suspended answers in the answer group, perform one of the following: •To reactivate all answers in the answer group, click the Activate Answers icon in the upper-right corner of the page. •To reactivate individual answers associated with the answer group, click the Activate Answer icon to the right of the answer in the General Configuration details page. 6. Click OK to confirm your decision and return to the Answer Groups list page. 7. To view the status of the suspended or activated answers, refer to Chapter 10, Monitoring GSS Global Server Load-Balancing Operation. Suspending or Reactivating All Answers in an Answer Group Associated with an Owner Answers added to answer groups can be grouped and managed according to GSS owner. Using a GSS owner to manage your answer groups simplifies the process to quickly suspend or activate related answers. To suspend or reactivate all answers in answer groups associated with a GSS owner: 1. From the primary GSSM GUI, click the Resources tab. 2. Click the Owners navigation link. The Owners list page appears (Figure 6-17). Figure 6-17 Owners List Page 3. Click the Modify Owner icon located to the left of the answer group that you want to suspend or reactivate. The Modifying Owner details page appears (Figure 6-18). Figure 6-18 Modifying Owners Details Page 4. Perform one of the following: •To suspend all answers in all answer groups associated with this owner, click the Suspend All Answers in All Groups for This Owner icon in the upper-right corner of the details page. •To reactivate all suspended answers associated with this owner, click the Activate All Answers in All Groups for This Owner icon in the upper-right corner of the details page. 5. Click OK to confirm your decision to suspend or activate the answers. You return to the Owner list page. Deleting an Answer Group To delete an answer group from the GSS, use the Delete Answer Group icon on the primary GSSM GUI to remove that answer group. 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. Refer to 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. Caution Deletions of any kind cannot be undone in the primary GSSM. If you might use the deleted data at a later point in time, we recommend performing a database backup of your GSSM. Refer to the Cisco Global Site Selector Administration Guide for details. To delete an answer group: 1. From the primary GSSM GUI, click DNS Rules tab. 2. Click the Answer Groups navigation link. The Answer Groups list page appears. 3. Click the Modify Answer Group icon located to the left of the answer group that you want to remove. The Modifying Answer Group details page appears (see Figure 6-16). 4. Click the Delete Answer Group icon in the upper right corner of the page. The GSS software prompts you to confirm your decision to delete the answer group. 5. Click OK to confirm your decision and return to the Answer Groups list page. Where to Go Next Chapter 7, Building and Modifying DNS Rules, describes constructing the DNS rules that govern all global server load balancing on your GSS network.
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