Note

There may be situations (for example, e-commerce, and other sites with multiple services) where you need to configure a wide IP so that connections are not sent to a given address unless multiple ports or services are available. You configure this behavior after you define the wide IP. For details, see An example configuration using a port list .

Understanding pools

A wide IP contains one or more pool definitions. A pool is a group of virtual servers to which the 3-DNS Controller load balances. You can include all types of virtual servers (BIG-IP system, EDGE-FX system, and host) in a pool definition.

Defining a wide IP

After you determine which virtual servers you should place in which wide IP pools, you are ready to add the first wide IP to the configuration. Note that you must configure at least one pool in the wide IP, but you may configure any number of pools.

To define a wide IP using the Configuration utility

1. In the navigation pane, click Wide IPs.
   The Wide IP List screen opens.
   
   
2. On the toolbar, click Add Wide IP.
   The Add a New Wide IP screen opens.
   
   
3. Add the wide IP settings, and click Next.
   The Configure Load Balancing for New Pool screen opens.
   
   
4. Add the pool settings, and click Next.
   The Select Virtual Servers screen opens.
   
   
5. Check the virtual servers that you want to add to the pool, and click Finish.
   The wide IP is added to your configuration.
   
   

Repeat this process for each wide IP you want to add. For help on defining wide IPs and pools, click Help on the toolbar.

Note

Using wildcard characters in wide IP names

The 3-DNS Controller supports wildcard characters in wide IP names and wide IP aliases. You can use the wildcard characters to simplify your maintenance tasks if you have a large quantity of wide IP names and/or wide IP aliases. The wildcard characters you can use are the question mark ( ? ), and the asterisk ( * ). The guidelines for using the wildcard characters are as follows:

• The question mark ( ? )
  
  
  • You can use the question mark to replace a single character, with the exception of dots ( . ).
    
    
  • You can use more than one question mark in a wide IP name or alias.
    
    
  • You can use both the question mark and the asterisk in the same wide IP name or alias.
    
    
• The asterisk ( * )
  
  
  • You can use the asterisk to replace multiple consecutive characters, with the exception of dots ( . ).
    
    
  • You can use more than one asterisk in a wide IP name or alias.
    
    
  • You can use both the question mark and the asterisk in the same wide IP name or alias.

The following examples are all valid uses of the wildcard characters for the wide IP name, www.mydomain.net.

• ???.mydomain.net
  
  
• www.??domain.net
  
  
• www.my*.net
  
  
• www.??*.net
  
  
• www.my*.*
  
  
• ???.my*.*
  
  
• *.*.net
  
  
• www.*.???
  
  

Note

An example of the wideip statement

Figure 2.7 shows a sample wideip statement. This statement defines a wide IP named mx.wip.siterequest.com, with an alias of mail.wip.siterequest.com. The wide IP contains two pools, with pool_1 receiving three times as many requests as pool_2. The 3-DNS Controller attempts to resolve requests sent to pool_1 using the Round Trip Times (RTT) mode. This mode sends connections to the virtual server in the pool that demonstrates the best round trip time between the virtual server and the client LDNS. If the 3-DNS Controller cannot resolve the request using the RTT mode, the system distributes requests using the Random load balancing mode. The 3-DNS Controller distributes requests at a 2:1 ratio to the two virtual servers defined in pool_2, where the first listed virtual server receives twice as many connections as the second.

Using the LDNS round robin wide IP attribute

LDNS round robin is an attribute that you can use in conjunction with any load balancing mode. The LDNS round robin attribute allows the 3-DNS Controller to return a list of available virtual servers, instead of a single virtual server. Certain browsers keep the answer returned by DNS servers. By enabling this attribute, the 3-DNS Controller returns a maximum of 16 virtual servers as the answer to a DNS resolution request. This provides browsers with alternate answers if a virtual server becomes unavailable.

Using the last resort pool designation

The last resort pool is an optional setting for a wide IP pool. The wide IP pool that you designate as the last resort pool, in the Configure Load Balancing for New Pool screen, is the virtual server pool that the 3-DNS Controller uses when all other pools have reached their thresholds or are unavailable for any reason. The 3-DNS Controller uses the last resort pool only when it tries, unsuccessfully, to load balance to the virtual servers in all other configured pools.

When your network includes cache appliances that host content from an origin site, you can designate the origin site as the last resort pool to handle requests if your cache virtual servers have reached their thresholds. You can also use the last resort pool to designate an overflow network so your origin servers remain available if network traffic spikes. You can only designate one last resort pool within a wide IP.

To designate a last resort pool using the Configuration utility

1. In the navigation pane, select Wide IPs.
   The Wide IP List screen opens.
   
   
2. From the Pools column, select the pools for the wide IP for which you want to create a last resort pool.
   The Modify Wide IP Pools screen opens.
   
   
3. From the Pool Name column, click the pool that you want to designate as the last resort pool.
   The Modify Load Balancing for [pool name] screen opens.
   
   
4. Check the box next to Last Resort Pool, and click Update.
   
   

To designate a last resort pool from the command line

In the wideip.conf file, change the last_resort definition from no to yes for the pool that you want to designate as the last resort pool. Figure 2.8 shows an example of a last resort pool definition

Working with the ECV service monitor

When you set up an extended content verification (ECV) service monitor for a wide IP, you can monitor not only the availability of a port or service on a server, but also the availability of a specific file on a particular server. An ECV service monitor verifies whether a specific file is available using the HTTP, HTTPS, or FTP network services. You can also specify a search string for the ECV monitor. When you specify a search string, the 3-DNS Controller not only verifies that a file is available, but also that whatever you specify in the search string is in the file.

An ECV service monitor can help you ensure that clients are getting what they are after, and that they will not get an error, whether they are looking for information, making an online purchase, or uploading software.

An ECV service monitor works in the following manner: if the node that hosts the requested file responds appropriately to the ECV query, the 3-DNS Controller marks the virtual server where the node resides as up, and the controller sends the client connection request to that virtual server. If the node does not respond as expected to the ECV query, the 3-DNS Controller marks the virtual server where the node resides as down, and the controller does not send connections to that server.

Note

Defining ECV service monitors

You can define ECV service monitors using the Configuration utility, or from the command line. You define ECV monitors for wide IPs only.

To define ECV service monitors using the Configuration utility

1. In the navigation pane, click Wide IPs.
   The Wide IP List screen opens.
   
   
2. In the Wide IP column, click the wide IP to which you want to add an ECV service monitor.
   The Modify Wide IP screen opens.
   
   
3. Add the settings for the ECV near the bottom of the screen, and click Update. For more information on the ECV settings, click Help on the toolbar.
   
   

To define ECV service monitors from the command line

1. To ensure that the configuration files contain the same information as the memory cache, type the following command:
   
   

   3ndc dumpdb

2. Open the wideip.conf file in a text editor (either vi or pico).
   
   
3. Use the syntax shown in Figure 2.9 to define an ECV service monitor. You should place all ECV service monitor statements just before the wide IP pool definitions in the wideip.conf file.
   
   
4. Save and close the file.
   
   
5. Commit the changes to the configuration by typing:
   
   

   3ndc reload

Figure 2.10 shows a sample ECV statement that defines an ECV service monitor in the wideip.conf file.

Note

Using the search string option

With the search string option, you can specify text or characters that you want the ECV monitor to verify within the file. The search string functionality is based on POSIX regular expression matching. Regular expressions are a matching tool for text and characters within a file. When you include a search string in an ECV service monitor, the 3-DNS Controller not only verifies that the file exists, but also that whatever text you type for the search string is available, exactly as you typed it, within the file. The most basic search string options are simply text. For a more advanced search string, you can use the POSIX regular expression characters shown in Table 2.2 .

Note

man re_format

Changing global variables that affect load balancing

You can configure global variables that affect how load balancing is handled on a global basis for all wide IPs managed by the 3-DNS Controller. You can override these global settings for individual wide IPs as necessary.

Global variables that affect load balancing fall into two categories:

• Alternate and fallback load balancing methods
  
  
• TTL (time to live) and timer values
  
  

The default settings for these variables are adequate for most configurations. However, if you want to change any global variable, you should refer to the online help.

Setting global alternate and fallback methods

You can configure a load balancing method that all wide IPs can use in the event that their preferred method fails.

To configure global alternate and fallback load balancing methods using the Configuration utility

1. In the navigation pane, click System.
   The System - General screen opens.
   
   
2. On the toolbar, click Load Balancing.
   
   
3. In the Default Alternate box, select the load balancing mode to use should a wide IP's preferred method fail.
   
   
4. In the Default Fallback box, specify the load balancing mode to use should the preferred and alternate methods fail.
   If all methods fail, requests are returned to DNS for resolution.
   
   
5. Finish configuring the rest of the settings on the System - Load Balancing screen. (For help on configuring the load balancing settings, click Help on the toolbar.)
   The global load balancing settings are added to your configuration.
   
   

To configure global alternate and fallback load balancing methods from the command line

1. To ensure that the configuration files contain the same information as the memory cache, type the following command:
   
   

   3ndc dumpdb

2. Open the wideip.conf file in a text editor (either vi or pico).
   
   
3. Locate or add the globals statement. The globals statement should be at the top of the file.
   
   
4. Use the syntax shown in Figure 2.11 to define global alternate and fallback load balancing methods.
   
   
5. Save and close the file.
   
   
6. Commit the changes to the configuration by typing:
   
   

   3ndc reload

Figure 2.12 shows a sample globals statement that defines global load balancing variables.

Understanding TTL and timer values

Each 3-DNS object has an associated time-to-live (TTL) value. A TTL is the amount of time (measured in seconds) for which metrics information is considered valid. The timer values determine how often the 3-DNS Controller refreshes the information.

Table 2.3 describes each TTL value, as well as its default setting.

Each 3-DNS object also has a timer value. A timer value defines the frequency (measured in seconds) at which the 3-DNS Controller refreshes the metrics information it collects. In most cases, the default values for the TTL and timer parameters are adequate. However, if you make changes to any TTL or timer value, keep in mind that an object's TTL value must be greater than its timer value.

Table 2.4 describes each timer value, as well as its default setting.

To configure global TTL and timer values using the Configuration utility

1. In the navigation pane, click System.
   The System - General screen opens.
   
   
2. To configure the default TTL for wide IPs, type a new value in the Default TTL box.
   
   
3. To configure other TTL and timer values, click Timers and Task Intervals on the toolbar.
   The System - Timers & Task Intervals screen opens.
   
   
4. Add the TTL and timer values settings.
   
   

For help on configuring the TTL and timer values settings, click Help on the toolbar.

To configure global TTL and timer values from the command line

1. To ensure that the configuration files contain the same information as the memory cache, type the following command:
   
   

   3ndc dumpdb

2. Open the wideip.conf file in a text editor (either vi or pico).
   
   
3. Locate or add the globals statement. The globals statement should be at the top of the file.
   
   
4. Use the syntax shown in Figure 2.13, on page 2-24 , to define global TTL and timer values.
   
   
5. Save and close the file.
   
   
6. Commit the changes to the configuration by typing:
   
   

   3ndc reload

Setting up load balancing for services that require multiple ports

Certain types of network traffic, such as FTP traffic or e-commerce traffic, require that more than one port be available in order for the client's requests to be properly handled. When you set up a load balancing configuration, you can define a port list for a wide IP. Before the 3-DNS Controller selects a virtual server to receive a connection, it verifies that the virtual server is up and available to receive connection requests. When the 3-DNS Controller receives a query, all of the ports in the port list must be available for each virtual server in the wide IP. If a virtual server does not have all ports in the port list available, the 3-DNS Controller marks it as unavailable for load balancing.

To configure multiple ports for a wide IP using the Configuration utility

1. In the navigation pane, click Wide IPs.
   
   
2. In the Wide IP column, click a wide IP name.
   The Modify Wide IP screen opens.
   
   
3. On the toolbar, click Port List.
   The Wide IP Port List screen opens.
   
   
4. Type a port number in the box or select a service from the list, then click the Add button.
   
   
5. Repeat step 4 for each port or service you need to add, then click Update.
   The port list is added to the wide IP configuration.
   
   

To configure multiple ports for a wide IP from the command line

1. To ensure that the configuration files contain the same information as the memory cache, type the following command:
   
   

   3ndc dumpdb

2. Open the wideip.conf file in a text editor (either vi or pico).
   
   
3. Locate the wideip statement you want to edit.
   
   
4. Add the port_list line as indicated in bold in Figure 2.14, on page 2-26 .
   
   
5. Save and close the file.
   
   
6. Commit the changes to the configuration by typing:
   
   

   3ndc reload

    

   Figure 2.14 Enabling multiple ports with the port_list option

   wideip {   address <ip_addr>   port <port_number> | <"service name">   name <"domain_name">   [ alias <"alias_name"> ]   [ ttl <number> ]   [ port_list <port_number> <port_number> ... ]   ...   [ pool_lbmode <rr | ratio | ga | random | topology> ]   [ pool definitions ...]

    

    

An example configuration using a port list

In the example shown in Figure 2.15 , you are setting up a site for selling a product on the Internet. This site contains a non-secure area that contains the product catalog, and a secure area for placing orders. You can configure a wide IP so that clients are sent to a virtual server only when both the secure and non-secure ports are available.

The key entry for this configuration is port_list. The port_list entry specifies that requests can be sent to virtual servers in this pool only if ports 80 (non-secure) and 443 (secure) are available.

For every virtual server address in the pool, a virtual server definition must exist for each port in the port list.

For the syntax example shown in Figure 2.15 , the BIG-IP systems and hosts must have the following virtual servers defined:

192.168.101.70:80

192.168.101.70:443

192.168.102.60:80

192.168.102.60:443

192.168.104.50:80

192.168.104.50:443

192.168.105.60:80

192.168.105.60:443

Troubleshooting manual configuration problems

Adding a wide IP requires careful planning and use of correct syntax. We recommend using the Configuration utility to create wide IPs and pools so that the correct syntax is generated automatically in the wideip.conf file. However, we have included the following recommendations to make it easier for you to spot and resolve any configuration problems if you choose to create your configuration by editing the wideip.conf file.

• Configuration utility
  The Configuration utility contains statistics screens that are useful in diagnosing problems, as they provide a snapshot of the 3-DNS Controller network at any given time. To use the statistics screens, expand the Statistics item in the navigation pane, then click either Wide IPs or Summary (and scroll until you see the Wide IP table).
  The Configuration utility also contains the Network Map, which allows you to see the relationships between your data centers, servers, and virtual servers, and the wide IPs and pools you created with the virtual servers. For information on working with the Network Map, click Help on the toolbar.
  
  
• wideip.conf syntax
  If you configure wide IPs from the command line, use the 3dparse utility to verify the wideip.conf syntax before you start 3dnsd. To use the 3dparse utility, type 3dparse on the command line. For details on the 3dparse utility, see the 3dparse man page.
  
  
• /var/log/3dns
  If you encounter an error that you cannot trace, you can view the log file in the Configuration utility, or you can directly open the /var/log/3dns file on your system. Using the UNIX grep utility, search for 3dnsd (for example, tail -100 /var/log/3dns | grep 3dnsd). This log file saves verbose error information, and should contain an explanation of the error.
  
  
• BIND syntax
  If you are setting up the configuration from the command line, and you are running the 3-DNS Controller in node mode, you may want to refer to one of the following BIND resources for help and background information:
  
  
  • The O'Reilly & Associates book, DNS and BIND, Third Edition
    
    
  • http://www.isc.org/bind.html
    
    

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