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Manual Chapter: Adding a new BIG-IP DNS to a BIG-IP DNS Synchronization Group
Manual Chapter
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Adding a new BIG-IP DNS to a BIG-IP DNS Synchronization Group

Overview: Adding a BIG-IP DNS system to a BIG-IP DNS synchronization group

You can configure BIG-IP® DNS (formerly (GTM)™) systems in collections called BIG-IP DNS synchronization groups. All BIG-IP DNS systems in the same BIG-IP DNS synchronization group have the same rank, exchange heartbeat messages, and share probing responsibility.

Configuration changes to one device in a BIG-IP DNS synchronization group are synchronized incrementally across the devices in the group. That is, only the data that has changed on a BIG-IP DNS device is synchronized to the other devices in the group. Although incremental synchronization is the default behavior, if an incremental synchronization fails, the system automatically performs a full configuration synchronization.

BIG-IP                 BIG-IP DNS systems in a synchronization group

BIG-IP DNS systems in a BIG-IP DNS synchronization group

When you add a BIG-IP® DNS system to a network that contains older BIG-IP DNS systems, the devices can exchange heartbeat messages, even though the BIG-IP software versions are different. However, to add BIG-IP DNS to a configuration synchronization group, you must run the gtm_add script.

Task summary

When adding BIG-IP® DNS to a network that already contains BIG-IP DNS systems in a synchronization group, perform the following tasks.

Enabling synchronization on the existing BIG-IP DNS

Ensure that BIG-IP® DNS references your NTP servers.

Decide to which BIG-IP DNS synchronization group you want to add the BIG-IP DNS system. Make certain that at least one previously-configured BIG-IP DNS belongs to that BIG-IP DNS synchronization group.

Enable synchronization on the system to ensure that the BIG-IP DNS system that is already installed on your network can share configuration changes with other BIG-IP DNS systems that you add to the BIG-IP DNS synchronization group.
  1. On the Main tab, click DNS > Settings > GSLB > General .
    The General configuration screen opens.
  2. Select the Synchronize check box.
  3. In the Group Name field, type the name of the synchronization group to which you want this system to belong.
  4. In the Time Tolerance field, type the maximum number of seconds allowed between the time settings on this system and the other systems in the synchronization group.
    The lower the value, the more often this system makes a log entry indicating that there is a difference.
    Tip: If you are using NTP, leave this setting at the default value of 10. In the event that NTP fails, the system uses the time_tolerance variable to maintain synchronization.
  5. Click Update.
When a change is made on one BIG-IP DNS system in the BIG-IP DNS synchronization group, that change is automatically synchronized to the other systems in the group.

Creating a data center on the existing BIG-IP DNS

Create a data center on the existing DNS system to represent the location where the new BIG-IP DNS system resides.
  1. On the Main tab, click DNS > GSLB > Data Centers .
    The Data Center List screen opens.
  2. Click Create.
    The New Data Center screen opens.
  3. In the Name field, type a name to identify the data center.
    Important: The data center name is limited to 63 characters.
  4. In the Location field, type the geographic location of the data center.
  5. In the Contact field, type the name of either the administrator or the department that manages the data center.
  6. From the State list, select Enabled or Disabled.
    The default is Enabled, which specifies that the data center and its resources are available for load balancing.
  7. Click Finished.

Defining a server on the existing BIG-IP DNS

Ensure that a data center where the new DNS system resides is available in the configuration of the existing BIG-IP DNS.
Define a new server, on the existing BIG-IP DNS system, to represent the new BIG-IP DNS system.
  1. On the Main tab, click DNS > GSLB > Servers .
    The Server List screen opens.
  2. Click Create.
    The New Server screen opens.
  3. In the Name field, type a name for the server.
    Important: Server names are limited to 63 characters.
  4. From the Product list, select BIG-IP System.
  5. In the Address List area, add the IP address of the server.
    Important: You must use a self IP address for a BIG-IP® system; you cannot use the management IP address.
  6. From the Data Center list, select the data center where the server resides.
  7. From the Virtual Server Discovery list, select how you want virtual servers to be added to the system.
    Option Description
    Disabled The system does not use the discovery feature to automatically add virtual servers. This is the default value. Use this option for a standalone BIG-IP DNS system or for a BIG-IP DNS/LTM® combo system when you plan to manually add virtual servers to the system, or if your network uses multiple route domains.
    Enabled The system uses the discovery feature to automatically add virtual servers. Use this option for a BIG-IP DNS/LTM combo system when you want the BIG-IP DNS system to discover LTM virtual servers.
    Enabled (No Delete) The system uses the discovery feature to automatically add virtual servers and does not delete any virtual servers that already exist. Use this option for a BIG-IP DNS/LTM combo system when you want the BIG-IP DNS system to discover LTM virtual servers.
  8. In the Virtual Server List area, if you selected Disabled from the Virtual Server Discovery list, specify the virtual servers that are resources on this server.
    1. In the Name field, type the name of the virtual server.
    2. In the Address field, type the IP address of the virtual server.
    3. From the Service Port list, select the port the server uses.
    4. Click Add.
  9. Click Create.
    Note: The gtmd process on each BIG-IP DNS system will attempt to establish an iQuery® connection over port 4353 with each self IP address defined on each server in the BIG-IP DNS configuration of type BIG-IP. Allow port 4353 in your port lockdown settings for iQuery® to work.
    The Server List screen opens displaying the new server in the list.
The status of the newly defined BIG-IP DNS system is Unknown, because you have not yet run the gtm_add script.

Running the gtm_add script

Determine the self IP address of a DNS system in the BIG-IP DNS synchronization group to which you want to add another BIG-IP DNS.
Run the gtm_add script on the BIG-IP DNS system you are adding to your network to acquire the configuration settings from a BIG-IP DNS system that is already installed on your network. For additional information about running the script, see SOL13312 on AskF5.com (www.askf5.com).
Note: The BIG-IP DNS and other BIG-IP systems must have TCP port 22 open between the systems for the script to work.You must perform this task from the command-line interface.
  1. Log in as root to the BIG-IP DNS system you are adding to your network.
  2. Run this command to access tmsh.
    tmsh
  3. Run this command to run the gtm_add script
    run gtm gtm_add
    1. Press the y key to start the gtm_add script.
    2. Type the IP address of the BIG-IP DNS system in the synchronization group to which you are adding this BIG-IP DNS system.
    3. Press Enter.
    4. If prompted, type the root password.
    5. Press Enter.
The BIG-IP DNS system you are installing on your network acquires the configuration of the BIG-IP DNS system already installed on your network.

Implementation result

The new BIG-IP® DNS system that you added to the network is a part of a BIG-IP DNS synchronization group. Changes you make to any system in the BIG-IP DNS synchronization group are automatically propagated to all other BIG-IP DNS systems in the group.

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