Load balancing with the Session Initiation Protocol proxy server

Load Balancer for IBM® WebSphere® Application Server can help maximize the potential of your website by providing a powerful, flexible, and scalable solution to peak-demand problems. Configuration of a load balancer is critical to prevent any single points of failure at Session Initiation Protocol (SIP) proxy. Configuration of a load balancer is required when more than one SIP proxy is deployed.

1. Start the Load Balancer.
   1. From the command prompt, type dsserver start
   2. Then type lbadmin to start the administrative console for the Load Balancer.
   3. From the administrative console, right-click Dispatcher, and then select Connect to Host
   4. Right-click the host name, and select Start Executor.
2. Start the configuration wizard for the Load Balancer.
   1. Select default host.
   2. Type a cluster address.
      You cannot ping the cluster address before the Executor starts.
   3. Define your SIP traffic port.
      Type a port number, such as 5060. You must specify this same value for port when you create a user-defined port in on your proxy server.
   4. Add each server to which the Load Balancer proxies traffic.
      In your configuration, the load balanced server is the proxy server for your configuration.
   5. Start an advisor by typing the name of the advisor.
      For example, start the HTTP advisor for HTTP traffic. For SIP traffic, start the SIP advisor. The advisor tells the manager if a specific port is accepting traffic.
3. Set up a loopback address on the physical proxy server host that represents the Virtual IP address for the cluster that is defined on the load balancer.
   Refer to the topic on configuring the server machines in the Load Balancer documentation.
4. Configure an IP sprayer from the application server's administrative console
   1. From the administrative console, click Servers > Server Types > WebSphere proxy servers > proxy_server_name > SIP proxy server settings > SIP proxy settings.
   2. Scroll down to the health checking setting for Load Balancer, and specify the physical IP address of the host on which Load Balancer is installed.
   3. Specify the SIP health check method name.
      The IBM Load Balancer uses OPTIONS as its method name.
   4. Click on Apply, and save your actions.
5. Optional: From the administrative console, define custom properties for the SIP proxy server. These custom properties can be used for defining SIP Proxy Load Balancer Health checking.
   1. In the Additional Properties section, click Custom properties.
   2. Ensure that Proxy servers have both the LBIPAddr and SIPAdvisorMethodName custom properties defined.
      The information for these custom properties is:

      Name	Value
      LBIPAddr	Physical IP address of the machine where the IBM Load Balancer is installed
      SIPAdvisorMethodName	OPTIONS

      Specify a value for these SIP proxy custom properties, and click OK.

      Attention: These settings are now available from the SIP proxy settings page in the administrative console, and they do not require that a custom property be set, but defining the custom properties is supported. If the custom property is set, the value of the custom property takes precedence over the value that you set in the administrative console.
6. Create a user-defined port from the application server's administrative console.
   1. From the administrative console, click Servers > Server Types > WebSphere proxy servers > proxy_server_name > Ports > New.
   2. Select User-defined port.
   3. Enter SIP_LB_Address for the Port Name field.
   4. Enter a value for the Host field.
      This is the virtual IP (cluster address) that is configured on your load balancer.
   5. Enter a value for the Port field.
      This value corresponds to the port through which the load balanced servers are configured to accept traffic from the load balancer machine. Consider the load balanced servers to be your proxy servers for this configuration.
   6. Click Apply, and then click Save.
7. Modify the SIP proxy transports from the administrative console.
   1. From the administrative console, click Servers > Server Types > WebSphere proxy servers > proxy_server_name > SIP container transport chains > UDP_SIP_PROXY_CHAIN > UDP Inbound Channel.
   2. Under the SIP proxy transports section, modify UDP_SIP_PROXY_CHAIN.
   3. From the Port menu, select SIP_LB_Address.
   4. Click Apply, and click Save.
8. Restart the proxy server to save your changes.