Configuring the server machines

About this task

You need to configure each of the back-end server machines in your topology before Load Balancer will be able to properly work in your environment.

Dispatcher will only load balance across servers that allow the loopback adapter to be configured with an additional IP address, for which the back-end server will never respond to ARP (address resolution protocol) requests.

Procedure

  1. Configure the loopback method.
  2. Check for an extra route. On some operating systems, a default route may have been created and needs to be removed. If problems are encountered with routing after aliasing, remove the alias and add it back using a different netmask.
    Note: Any extra routes should be ignored on Windows 2003.
    • [Windows] Check for an extra route on Windows operating systems with the following command:
      route print
      For example:
      1. After route print is entered, a table similar to the following example will be displayed. This example shows finding and removing an extra route to cluster 9.67.133.158 with a default netmask of 255.0.0.0.
        Active Routes:
        
        Network Address    Netmask            Gateway Address       Interface          Metric
        0.0.0.0            0.0.0.0            9.67.128.1            9.67.133.67         1 
        9.0.0.0            255.0.0.0          9.67.133.158          9.67.133.158        1 
        9.67.128.0         255.255.248.0      9.67.133.67           9.67.133.67         1 
        9.67.133.67        255.255.255.255    127.0.0.1             127.0.0.1           1 
        9.67.133.158       255.255.255.255    127.0.0.1             127.0.0.1           1 
        9.255.255.255      255.255.255.255    9.67.133.67           9.67.133.67         1 
        127.0.0.0          255.0.0.0          127.0.0.1             127.0.0.1           1 
        224.0.0.0          224.0.0.0          9.67.133.158          9.67.133.158        1 
        224.0.0.0          224.0.0.0          9.67.133.67           9.67.133.67         1 
        255.255.255.255    255.255.255.255    9.67.133.67           9.67.133.67         1 
      2. Find your cluster address under the “Gateway Address” column. If you have an extra route, the cluster address will appear twice. In the example given, the cluster address (9.67.133.158) appears in row 2 and row 8.
      3. Find the network address in each row in which the cluster address appears. You need one of these routes and will need to delete the other route, which is extraneous. The extra route to be deleted is the one whose network address begins with the first digit of the cluster address, followed by three zeroes. In the example shown, the extra route is the one in row two, which has a network address of 9.0.0.0:
        Network Address    Netmask            Gateway Address       Interface          Metric
        9.0.0.0            255.0.0.0          9.67.133.158          9.67.133.158        1
    • [AIX][HP-UX][Linux][Solaris] Check for an extra route on all Linux and UNIX systems with the following command:
      netstat -nr 
  3. Delete any extra route. You must delete the extra route. Use the command for your operating system shown below:
    • [AIX]
      route delete -net network_address cluster_address
    • [HP-UX]
      route delete cluster_address cluster_address
    • [Windows]
      route delete network_address cluster_address
      Note: You must delete the extra route every time you reboot the server.
      To delete the extra route as shown in the ″Active Routes″ example above, enter:
      route delete 9.0.0.0 9.67.133.158

      On Windows 2003, it is not possible to delete routes. Any extra routes should be ignored on Windows 2003. If problems are encountered with routing after aliasing, remove the alias and add it back using a different netmask.

  4. [AIX] Configure the workload partition (WPAR) as a backend server. Run all of the following commands on the machine that hosts the WPAR.
    1. Enable WPAR specific routing. Enter the following command:
      chwpar -i -I rtdest=default rtgateway=<Default_Gateway> <WPAR_name>
    2. Configure the IP address for the cluster on the loopback interface of the WPAR.
      chwpar -N interface=lo0 address=<cluster_IP_address> netmask=255.255.255.0 <WPAR_name>
  5. Verify that the server is properly configured. To verify if a backend server is properly configured, perform the following steps from a different machine on the same subnet when the Load Balancer is not running and cluster is unconfigured:
    1. Issue the arp command. For example:
      arp -d cluster
    2. Issue the ping command. For example:
      ping cluster

      There should be no response. If there is a response to the ping, ensure that you did not ifconfig the cluster address to the interface. Ensure that no machine has a published arp entry to the cluster address.

    3. Ping the back-end server, then immediately issue the arp -a command For example:
      arp -a
      In the output from the command, you should see the MAC address of your server. Issue the command:
      arp -s cluster server_MAC_address
    4. Ping the cluster. You should get a response. Issue a http, telnet, or other request that is addressed to the cluster that you expect your back-end server to handle. Ensure that it works properly.
    5. Issue the arp -d command. For example:
      arp -d cluster
    6. Ping the cluster. There should be no response. If there is a response, issue an arp cluster instruction to get the MAC address of the machine that is not configured correctly, and repeat steps 1 through 6.
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Last updated: January 17, 2013 11:24 AM EST
File name: tcfg_configservers.html