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Archived Manual Chapter: BIG-IP Solutions Guide v4.1: Installing a BIG-IP without Changing the IP Network
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Installing a BIG-IP without Changing the IP Network



Installing a BIG-IP without changing IP networks

A combination of several features of the BIG-IP allows you to place a BIG-IP in a network without changing the existing IP network.

The following figure shows the data center topology before you add the BIG-IP. The data center has one LAN, with one IP network, 10.0.0.0. The data center has one router to the Internet, two web servers, and a back-end mail server.

Figure 3.1 Existing data center network structure

The existing data center structure does not support load balancing or high availability. Figure 3.2 is an example of the data center topology after you add the BIG-IP.

Figure 3.2 New structure after adding the BIG-IP

Both the internal and external interfaces of the BIG-IP are on the same IP network, 10.0.0.0, but they are effectively on different LANs.

Note that a second switch has been introduced in Figure 3.2. This switch would be eliminated in a configuration using an IP Application Switch.

Configuring the BIG-IP for the same IP network

To configure the BIG-IP for this solution, you must complete the following tasks:

  • Remove the self IP addresses from the individual VLANs
    Remove the self IP addresses from the individual VLANs. Routing is handled by the self IP address you create for the VLAN group.
  • Create a VLAN group
    Create a VLAN group that includes the internal and external VLANs. This enables L2 forwarding. (L2 forwarding causes the two VLANs to behave as a single network.)
  • Create a self IP for the VLAN group
    The self IP for the VLAN group provides a route for packets destined for the network.
  • Create a pool of web servers
    Create a pool that contains the web servers that you want to load balance.
  • Create a virtual server
    Create a virtual server that load balances the web servers.

    Note: This example assumes that you are using the default internal and external VLAN configuration with self IP addresses on each VLAN that are on the same IP network on which you are installing the BIG-IP.

    Note: The default route on each content server should be set to the IP address of the router. In this example, you set the default route to 10.0.0.2.

Removing the self IP addresses from the individual VLANs

Remove the self IP addresses from the individual VLANs. After you create the VLAN group, you will create another self IP address for the VLAN group for routing purposes. The individual VLANs no longer need their own self IP addresses.

Warning: We recommend that you perform this step from the console or from a self IP address you are not going to delete. If you are connected from a remote workstation though a self IP address you are going to delete, you will be disconnected when you delete it.

To remove the self IP addresses from the default VLANs using the Configuration utility

  1. In the navigation pane, click Network.
    The VLANs screen opens.
  2. In the VLANs screen, click the Self IP Addresses tab.
    The Self IP Addresses screen opens.
  3. Delete the self IP addresses for the external and internal VLANs. (For additional information about adding and removing self IP addresses, click the Help button.)

    To delete self IP addresses from the individual VLANs from the command line

    To delete the self IP addresses from the individual VLANs, use the following syntax.

    b self <ip addr> delete

    Repeat the command to delete each self IP address on the internal and external VLANs.

Creating a VLAN group

Create a VLAN group that includes the internal and external VLANs. Packets received by a VLAN in the VLAN group are copied onto the other VLAN in the group. This allows traffic to pass through the BIG-IP on the same IP network. For more information about VLAN groups, refer to the BIG-IP Reference Guide, Chapter 2.

Tip: A VLAN group name can be used anywhere a VLAN name can be used.

To create a VLAN group from the Configuration utility

  1. In the navigation pane, click Network.
    The VLANs screen opens.
  2. In the VLANs screen, click the VLAN Groups tab.
    The VLAN Groups screen opens.
  3. In the VLAN Groups screen, click the Add button to add the VLAN group.

    Configuration notes

    For this example:

    The VLAN group name is myvlangroup.

    Make sure the Proxy Forward box is checked.

    Add the internal and external VLANs to the VLAN group.

    To create a VLAN group from the command line

    To create the VLAN group myvlangroup from the command line, type the following command:

    b vlangroup myvlangroup { vlans add internal external }

Creating a self IP for the VLAN group

The self IP for the VLAN group provides a route for packets destined for the network. With the BIG-IP, the path to an IP network is a VLAN. However, with the VLAN group feature used in this example, the path to the IP network 10.0.0.0 is actually through more than one VLAN. Since IP routers are designed to have only one physical route to a network, a routing conflict can occur. The self IP address feature on the BIG-IP allows you to resolve the routing conflict by putting a self IP address on the VLAN group.

To create a self IP address for a VLAN group using the Configuration utility

  1. In the navigation pane, click Network.
    The VLANs screen opens.
  2. In the VLANs screen, click the Self IP Addresses tab.
    The Self IP Addresses screen opens.
  3. In the Self IP Addresses screen, click the Add button to start the Add Self IP Address wizard

    Configuration notes

    For the example in Figure 3.2:

    The self IP address you add for the VLAN group is 10.0.0.6.

    When you choose the VLAN you want to apply the self IP address to, select the VLAN group you created that contains the internal and external VLANs.

    To create a self IP address for a VLAN group from the command line

    To create a self IP address on the VLAN group, type the following command:

    b self 10.0.0.6 vlan myvlangroup

Creating the pool of web servers to load balance

After you create the network environment for the BIG-IP, you can create the pool of web servers you want to load balance.

To create a pool using the Configuration utility

  1. In the navigation pane, click Pools.
    The Pools screen opens.
  2. In the Pools screen, click the Add button to start the Add Pool wizard.

    Configuration note

    For this example, the pool contains the web servers 10.0.0.3:80 and 10.0.0.4:80.

    To create a pool from the command line

    To create a pool from the command line, type the following command:

    b pool mywebpool { member 10.0.0.3:80 member 10.0.0.4:80 }

    In this example, you create the pool name mywebpool with the members 10.0.0.3 and 10.0.0.4.

Creating the virtual server to load balance the web servers

After you create the pool of web servers you want to load balance, you can create the virtual server.

To create a virtual server using the Configuration utility

  1. In the navigation pane, click Virtual Servers.
    The Virtual Servers screen opens.
  2. Click Add (+)
    The Add Virtual Servers screen opens.
  3. Enter the virtual server address and pool name. (For additional information about adding and removing self IP addresses, click the Help button.)

    Configuration note

    Create virtual server 10.0.0.5 using pool mywebpool.

    To create a virtual server from the command line

    To create the virtual server for this example from the command line, type the following command:

    b virtual 10.0.0.5:80 use pool mywebpool

    In this example, mywebpool contains the web servers.

Additional configuration options

Whenever a BIG-IP is configured, you have a number of options:

  • You have the option in all configurations to configure a BIG-IP redundant system for fail-over. Refer to Chapter 5, Configuring a Redundant System, in the BIG-IP Reference Guide.
  • All configurations have health monitoring options. Refer to Health Monitors in Chapter 3, Configuring the High-Level Network, in the BIG-IP Reference Guide.
  • When you create a pool, there is an option to set up persistence and a choice of load balancing methods. Refer to Pools in the Chapter 3, Configuring the High-Level Network, in the BIG-IP Reference Guide.
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