Applies To:

Show Versions Show Versions

Manual Chapter: Configuration Guide for BIG-IP® version 9.2.2 Global Traffic Management: Working with Listeners - 4
Manual Chapter
Table of Contents   |   << Previous Chapter   |   Next Chapter >>


4

Working with Listeners


Introducing listeners

As traffic flows across your network, it is necessary to identify what traffic is relevant to your Global Traffic Managers for load balancing and other operations. A listener is a specialized resource that is assigned a specific IP address. When traffic is sent to that IP address, the listener alerts the Global Traffic Manager, allowing it to forward the traffic to the appropriate resource.

The IP address that you assign to a listener depends on the following criteria:

  • The configuration of the Global Traffic Managers and Local Traffic Managers in the data center
  • The number of VLANs (if any) on which the Global Traffic Manager is load balancing data

Listeners have another important role beyond just identifying the network packets that are relevant to the Global Traffic Manager: listeners also determine the operation mode in which the Global Traffic Manager operates. An operation mode defines the specific role or function the Global Traffic Manager servers on the network. These modes are:

  • Node
    The node mode is the traditional installation of the Global Traffic Manager. In this mode, the Global Traffic Manager replaces a DNS server in a network and uses the DNS server's IP address. All DNS traffic is directed at the Global Traffic Manager because it is registered with InterNIC as authoritative for the domain. In node mode, you usually run BIND on the system to manage DNS zone files. Also, you may use the ZoneRunner module included with the Global Traffic Manager to manage your zone files.
  • Bridge
    In bridge mode, the Global Traffic Manager acts as an IP bridging device by forwarding packets between two LAN segments (usually on the same IP subnet). The system usually has one IP address, and is installed between the router or switch, and the authoritative DNS server. The Global Traffic Manager does not replace the authoritative DNS server. The Global Traffic Manager filters all DNS packets that match wide IPs, and forwards the remaining packets to the authoritative DNS server for resolution. Note that this may be the preferred method of using the Global Traffic Manager because you do not have to replace the authoritative DNS server, and you can perform out-of-band testing before you deploy Global Traffic Manager software upgrades.
  • Router
    In router mode, the Global Traffic Manager acts as a router by forwarding packets between two different IP subnets. You can put the Global Traffic Manager anywhere in the network topology so that packets destined for the authoritative DNS server have to pass through it. Router mode requires at least two IP addresses and two VLANs. This mode is probably most useful for Internet service providers (ISPs) that want to redirect traffic to local content servers. For example, if you use the Global Traffic Manager in router mode, an ISP can redirect requests for ads.siterequest.net to a local ad server.

Selecting listeners

A listener is a specialized resource that forwards data sent to a specific IP address to the Global Traffic Manager. Selecting the correct listener is important; if the listener is configured to the wrong IP address, the Global Traffic Manager will not be aware of the data for which it is responsible.

The IP address you assign to a listener generally depends on what BIG-IP systems are in the data center. How you select a listener depends on the operation mode you want the Global Traffic Manager to use. You can select either node, bridge, or router mode, as described in Introducing listeners .

Selecting listeners for node mode operation

The node mode is the traditional installation of the Global Traffic Manager. In this mode, the Global Traffic Manager replaces a DNS server in a network and uses the DNS server's IP address. All DNS traffic is directed at the Global Traffic Manager because it is registered with InterNIC as authoritative for the domain.

If you want the Global Traffic Manager to operate in node mode, the listener you define depends on whether the Global Traffic Manager resides alone, with one or more Local Traffic Managers, or as a redundant pair of Global Traffic Managers:

  • Global Traffic Manager only
    In this configuration, the Global Traffic Manager resides independently of any other BIG-IP system on the given network segment. For such environments, the listener IP address corresponds to the self IP address of the Global Traffic Manager system.
  • Global Traffic Manager with a single Local Traffic Manager
    In this configuration, the Global Traffic Manager resides with a single Local Traffic Manager (this configuration is typically referred to as a combination, or "combo" box). For such environments, the listener IP address corresponds to the self IP address of the Global Traffic Manager system.
  • Global Traffic Manager with redundant Local Traffic Managers
    In this configuration, the Global Traffic Manager resides with both a primary Local Traffic Manager and a backup secondary Local Traffic Manager. For such environments, the listener IP address corresponds to the self IP address of the Global Traffic Manager system.
  • Redundant Global Traffic Managers
    In this configuration, the Global Traffic Manager is paired with a backup secondary Global Traffic Manager. For such environments, the listener IP address corresponds to the floating IP address shared between the Global Traffic Managers. A floating IP address is an IP address that points to the primary Global Traffic Manager system unless that system fails, at which time the backup system takes over the IP address until the primary system returns.

See Setting up listeners for more information on the steps needed to set up a listener.

Selecting listeners for bridge mode operation

In bridge mode, the Global Traffic Manager acts as an IP bridging device by forwarding packets between two LAN segments (usually on the same IP subnet). The system usually has one IP address, and is installed between the router or switch, and the authoritative DNS server. The Global Traffic Manager does not replace the authoritative DNS server. The Global Traffic Manager filters all DNS packets that match wide IPs, and forwards the remaining packets to the authoritative DNS server for resolution.

If you want the Global Traffic Manager to operate in bridge mode, you create a listener that represents each subnet for which the Global Traffic Manager acts as a bridge, such as 192.168.5.0, or 172.73.0.0. See Setting up listeners for more information on the steps needed to set up a listener.

Selecting listeners for router mode operation

In router mode, the Global Traffic Manager acts as a router by forwarding packets between two different IP subnets. You can put the Global Traffic Manager anywhere in the network topology so that packets destined for the authoritative DNS server have to pass through it. Router mode requires at least two IP addresses and two VLANs.

If you want the Global Traffic Manager to operate in router mode, you create a listener that represents a valid IP address that belongs to multiple VLANs, such as 192.168.5.0, or 172.73.0.0. See Setting up listeners for more information on the steps needed to set up a listener.

Setting up listeners

The Global Traffic Manager handles only network traffic sent to the IP address specified for any listeners that you create. The IP address that you supply for a listener typically is the IP address you assigned to the Global Traffic Manager.

In most situations, a Global Traffic Manager is responsible for traffic that traverses multiple VLANs. Consequently, you can configure a listener to monitor as many or as few VLANs as necessary. See VLANs and listeners for more information.

Common tasks you will perform while working with listeners include:

  • Configuring listeners
  • Modifying listeners
  • Deleting listeners

To set up a listener

  1. On the Main tab in the navigation pane, expand Global Traffic and then click Listeners.
    The main listeners screen opens.
  2. Click the Create button.
    The new listener screen opens.
  3. In the Destination box, type the IP address on which the Global Traffic Manager will listen for network traffic.
  4. From the VLAN Traffic list, select a VLAN setting appropriate for this listener. For additional assistance with this setting, please see the online help.
  5. Click the Finished button to save the new listener.

Repeat this process for any additional listeners.

Modifying listeners

After you create a listener, you can access its settings, changing them as needed. Common instances in which you need to modify a listener include adding an additional VLAN, or modifying the IP address of the listener.

To modify a listener

  1. On the Main tab in the navigation pane, expand Global Traffic and then click Listeners.
    The main listeners screen opens.
  2. Click the name of the listener.
    The properties screen for that listener appears.
  3. Modify the settings for the listener.
  4. Click the Update button to save your changes to the listener.

Deleting listeners

In the event that a listener is no longer needed within the Global Traffic Manager, you can delete it.

To delete a listener

  1. On the Main tab in the navigation pane, expand Global Traffic and then click Listeners.
    The main listeners screen opens.
  2. Check the Select check box that corresponds to the listener entry.
  3. Click the Delete button.
    A confirmation screen appears.
  4. Click the Delete button to delete the listener.

VLANs and listeners

In the event that the Global Traffic Manager is responsible for traffic on multiple VLANs, you must configure a listener for each VLAN. When you configure listeners for use in multiple-VLAN environments, you have the following options:

  • All VLANs
  • Enabled for specific VLANs
  • Disabled for specific VLANs

For more information about BIG-IP systems and VLANs, see the Configuration Guide for Local Traffic Management.

Setting up a listener for all VLANs

If the Global Traffic Manager resides on a network segment that does not use VLANs, or if the IP address you assign as a listener is valid for all VLANs for which the Global Traffic Manager is responsible, you set the VLAN Traffic option to All VLANs.

To set up a listener for all available VLANs

  1. On the Main tab in the navigation pane, expand Global Traffic and then click Listeners.
    The main listeners screen opens.
  2. Click the Create button.
    The new listener screen opens.
  3. In the Destination text box, type the IP address on which the Global Traffic Manager will listen for network traffic.
  4. From the VLAN Traffic list, select All VLANs.
  5. Click the Finished button to save your changes.

Enabling a listener for specific VLANs

If your installation of the Global Traffic Manager requires it to manage traffic for only some of the VLANs available on the network segment, you set the VLAN Traffic option to Enabled on.

To set up a listener for all available VLANs

  1. On the Main tab in the navigation pane, expand Global Traffic and then click Listeners.
    The main listeners screen opens.
  2. Click the Create button.
    The new listener screen opens.
  3. In the Destination box, type the IP address on which the Global Traffic Manager will listen for network traffic.
  4. From the VLAN Traffic list, select Enabled on.
    A new option, VLAN List, appears on the screen.
  5. Select the appropriate VLANs from the Available list and use the buttons provided to move them to the Selected list.
    The listener only alerts the Global Traffic Manager about traffic on the VLANs in the Selected list.
  6. Click the Finished button to save your changes.

Disabling a listener for specific VLANs

In instances where the Global Traffic Manager resides on a network segment with several VLANs, and you want to exclude some VLANs from listener, you set the VLAN Traffic option to Disabled on.

To set up a listener for all available VLANs

  1. On the Main tab in the navigation pane, expand Global Traffic and then click Listeners.
    The main listeners screen opens.
  2. Click the Create button.
    The new listener screen opens.
  3. From the VLAN Traffic list, select Disabled on.
    A new option, VLAN List, appears on the screen.
  4. Select the appropriate VLANs from the Available list and use the buttons provided to move them to the Selected list.
    The listener will alert the Global Traffic Manager about traffic on all VLANs except those listed in the Selected list.
  5. Click the Finished button to save your changes.



Table of Contents   |   << Previous Chapter   |   Next Chapter >>

Was this resource helpful in solving your issue?




NOTE: Please do not provide personal information.



Incorrect answer. Please try again: Please enter the words to the right: Please enter the numbers you hear:

Additional Comments (optional)