16

One IP Network Topologies

• Introducing the one-IP network topology
• Setting up a one-IP network topology with one interface
• Additional configuration options

Introducing the one-IP network topology

Another configuration option you can use with the BIG-IP is a the one-IP network topology. This differs from the typical two-network configuration it two ways:

• Because there is only one physical network, this configuration does not require more than one interface on the BIG-IP.
• Clients need to be assigned SNATs to allow them to make connections to servers on the network in a load balancing pool.
  
  

  The single interface configuration is shown in Figure 16.1.

  

  Figure 16.1 An example of a single interface topology

Setting up a one-IP network topology with one interface

To set up this configuration, you need to complete the following tasks on the BIG-IP:

• Create a load balancing pool for the content servers.
• Create a virtual server for the content server pool.
• Configure a SNAT for the client.

Defining the pools for an additional Internet connection

The first task required to set up this solution is to create a pool that contains all the content servers you want to load balance.

To create pools using the Configuration utility

1. In the navigation pane, click Pools.
   The Pools screen opens.
2. Click the Add button.
3. For each pool, enter the pool name and member addresses in the Add Pool screen. (For additional information about configuring a pool, click the Help button.)
   
   

   Configuration note

   For this example, you create a pool server_pool that contains the following members:
   <server1>:80
   <server2>:80

To define pools from the command line

To define the pool server_pool for the nodes, type the following command:

b pool server_pool { member <server1>:80 member <server2>:80 }

Replace <server1> and <server2> with IP address of the respective server.

Defining the virtual server

The second task required to set up this solution is to create a virtual server that references the pool of servers that you want to load balance. Use the pool you created in the previous step.

To define the virtual server using the Configuration utility

1. In the navigation pane, click Virtual Servers.
   The Virtual Servers screen opens.
2. Click the Add button.
3. For each virtual server, enter the virtual server address and pool name. (For additional information about configuring a virtual server, click the Help button.)
   
   

   Configuration note

   Create virtual server 192.168.13.1:80 and use pool server_pool.

To define the virtual server from the command line

Use the following command to create a virtual server for connecting to the servers:

bipipe virtual 192.168.13.1:80 use pool server_pool

Configuring the client SNAT

Finally, configure the BIG-IP to handle connections originating from the client. You must define a SNAT in order to change the source address on the packet to the SNAT external address, which is located on the BIG-IP. If a SNAT were not defined, the server would return the packets directly to the client without giving the BIG-IP the opportunity to translate the source address from the server address back to the virtual server. The client would not recognize the packet if the source address of the returning packet is the IP address of the real server because the client sent its packets to the IP address of the virtual server.

Configure the SNAT using the bigpipe snat command:

b snat map client1 to 192.168.13.99

Replace client1 with the actual name of the client in your configuration.

Additional configuration options

Whenever you configure a BIG-IP, a number of options are available to you:

• You have the option in all configurations to configure a BIG-IP redundant system for fail-over. Refer to Chapter 6, Configuring a Redundant System, in the BIG-IP Reference Guide.
• All configurations have health monitoring options. Refer to Health Monitors in Chapter 4, 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 4, Configuring the High-Level Network, in the BIG-IP Reference Guide.