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Manual Chapter: BIG-IP® version 9.4 Global Traffic Manager and Link Controller Implementations Guide: 6 - Adding New Global Traffic Managers to a Synchronization Group
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Adding New Global Traffic Managers to a Synchronization Group

Understanding synchronization in Global Traffic Manager version 9.x

Before 9.x, you synchronized 3-DNS Controllers (the precursor to Global Traffic Manager) through the use of sync groups. A sync group contained two components: a principal 3-DNS Controller, and one or more receiver 3-DNS Controllers. When you created a sync group, you specified which of the 3-DNS Controllers you wanted to use as the principal system. Any configuration changes you made on that system were then distributed to the secondary 3-DNS Controllers on the network.



Figure 6.1 An example of a 3-DNS Controller sync group

With the 9.x line of Global Traffic Manager, specific sync groups no longer exist. Instead, Global Traffic Manager systems reside in more generalized collections, called synchronization groups. Although the names are similar, there are significant feature changes. For example, in these groups, all Global Traffic Manager systems have the same rank; in other words, the principal/receiver hierarchy present in the 4.x line no longer exists. This change allows you to modify the Global Traffic Manager settings from any system; these changes are then sent to all other Global Traffic Managers within the same synchronization group.



Figure 6.2 An example of a synchronization group

To be part of a synchronization group, a Global Traffic Manager:

  • Must have its Synchronization option enabled
  • Must have a Synchronization Group name that other Global Traffic Managers also share

The synchronization operations in 9.x operate in the following manner:

  • At regular intervals, each Global Traffic Manager uses the iQuery protocol to compare the timestamp of its configuration files against the timestamps on any other Global Traffic Manager in its synchronization group.
  • If the system detects a newer configuration file, it downloads and uses those files.

This process ensures the rapid distribution of Global Traffic Manager settings to any other systems that belong to the same synchronization group.

One exception to this process occurs when you add a new Global Traffic Manager to the network. In this scenario, there is a chance that the timestamp of the new systems configuration file is newer than the files on the already-installed Global Traffic Manager. If you enabled synchronization at this point, the unconfigured configuration file would be distributed to the existing Global Traffic Managers, effectively removing your existing configurations.

You can avoid the accidental synchronization of an unconfigured configuration file to existing Global Traffic Managers through the use of the gtm_add script. This script acquires the configuration file from an existing Global Traffic Manager and applies it to the new system. As a result, the new system has the current configuration for your network.

Adding a new Global Traffic Manager to a synchronization group

This implementation focuses on the fictional company, SiteRequest. Currently, the SiteRequest network has two data centers: one located in New York; the other in Los Angeles.

Until recently, SiteRequest had a single Global Traffic Manager located at the New York data center, with an IP address of However, recent increases in DNS traffic have prompted the integration of a new Global Traffic Manager at the Los Angeles data center. These two Global Traffic Managers must belong to the same synchronization group, allowing changes made to one system to transfer over to the other. For the purposes of this solution, both Global Traffic Managers are the same version, and the the Global Traffic Manager in New York is already active and communicating with the rest of the network.

At this point in the example, the new Global Traffic Manager is connected to the network and assigned the IP address, SiteRequest also has a data center object defined on the Global Traffic Manager located in New York, and has named this new data center: Los Angeles Data Center. This data center contains the various BIG-IP systems that reside in Los Angeles. Finally, you have two Local Traffic Managers; one at each data center. The Local Traffic Manager in New York has an IP address of; the one in Los Angeles has an IP address of

The tasks you must complete to add a new Global Traffic Manager to a synchronization group are:

  • Add the Global Traffic Manager to the configuration
  • Enable synchronization
  • Run the gtm_add script
  • Run the bigip_add script

Adding the Global Traffic Manager

The first task you must accomplish is adding the Los Angeles Global Traffic Manager to the New York Global Traffic Manager.

To add the Global Traffic Manager

  1. On the Main tab of the navigation pane, expand Global Traffic and then click Servers.
    The main screen for servers opens.
  2. Click the Create button.
    The New Server screen opens.
  3. In the Name box, type the name of the sever.
    For this example, type Los Angeles GTM.
  4. From the Product list, select the server type.
    In this example, select BIG-IP System (Single).
  5. In the Address List option, complete the following tasks:
    • In the Address box, type the IP address of the server.
      In this example, type
    • Click the Add button
  6. From the Data Center list, select the data center to which the server belongs.
    For this example, select Los Angeles Data Center.
  7. From the Virtual Server Discovery list, select Disabled.
  8. Click the Create button to create the server object that defines the Global Traffic Manager at the selected data center.

Enabling synchronization

For the next step, you need to enable the Synchronization option and assign an appropriate name for the synchronization group. For this solution, the synchronization group name is North America.

To enable synchronization

  1. On the Main tab of the navigation pane, expand System and then click General Properties.
    The general properties screen opens.
  2. From the Global Traffic menu, choose General.
    The General global properties screen opens.
  3. Check the Synchronization check box.
  4. Check the Synchronize DNS Zone Files check box.
  5. In the Synchronization Group Name box, type the name of the group.
    In this example, type North America.
  6. Click the Update button to save your changes.

Running the gtm_add script

Next, you need to have the new Global Traffic Manager acquire the settings established on an existing Global Traffic Manager. In this example, the Global Traffic Manager in Los Angeles acquires the configurations established at the New York data center. You must do this before you attempt to synchronize these systems; otherwise, you run the risk of having the new Global Traffic Manager, which is unconfigured, replace the configuration of the New York system. To acquire the configuration files, you run the gtm_add script.

To run the gtm_add script

  1. Log in to the unconfigured Global Traffic Manager.
  2. At the command prompt, type gtm_add.
    A prompt appears, describing what the gtm_add script does and asking if you are sure you want to run the process.
  3. Press the y key to start the gtm_add script.
    The script then prompts you for the IP address of the system from which you want to acquire configuration settings.
  4. Type the IP address of the configured Global Traffic Manager.
    For this example, type
  5. Press Enter.

At this point, both Global Traffic Managers share the same configuration. In addition, they also belong to the same synchronization group, because the gtm_add script copied the settings from the existing Global Traffic Manager to the new Global Traffic Manager.

Running the bigip_add script

With the new unit added to the existing unit, you can now access the new system and run the bigip_add script. This script exchanges SSL certificates so that each system is authorized to communicate with the other. In this example, you run this script from the Global Traffic Manager in the Los Angeles data center.

To run the bigip_add script

  1. Log in to the command line interface for the Global Traffic Manager.
  2. At the prompt, type bigip_add <ip addresses>.
    In this example, type bigip_add
  3. Note: Notice that, in this example, you have included the IP address of the Global Traffic Manager in New York.
  4. Press the Enter key to run the script.

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