Administering Back-End Servers in ILB

You can use the ilbadm to add, remove, enable, and disable one or more back-end servers within server groups. For a list of definitions, see ILB Terminology.

How to Add a Back-End Server to a Server Group

• Add a back-end server to a server group.

  Server specifications must include a host name or IP address and can also include an optional port or a range of ports. Server entries with the same IP address are disallowed within a server group.

  # ilbadm add-server -s server=192.168.89.1,192.168.89.2 ftpgroup
  # ilbadm add-server -s server=[2001:7::feed:6]:8080 sgrp

  The -e option enables the servers in addition to adding them to the group.

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  Note - IPv6 addresses must be enclosed in square brackets.

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Example 23-3 Adding a Back-End Server to a Server Group

The following example adds servers to server groups ftpgroup and sgrp, and enables them.

# ilbadm add-server -s server=192.168.89.1,192.168.89.2 ftpgroup
# ilbadm add-server -e -s server=[2001:7::feed:6]:8080 sgrp

How to Remove a Back-End Server From a Server Group

1. To remove a server from a specific server group, follow these steps:
   1. Identify the server ID of the server that you want to remove from a server group. The server ID can be obtained from the output of show-servergroup -o all subcommand.
   2. Remove the server.

      # ilbadm remove-server -s server=_sg1.2 sg1

2. To remove a server from all server groups, follow these steps given below:
   1. Identify the IP address and the host name of the server you want to remove.
   2. Use the output of the ilbadm show-servergroup-o all command to identify the server groups that include the server.
   3. For each server group, run the following subcommand to remove the server from the server group.

Example 23-4 Removing a Back-Server From a Server Group

The following example removes the server with server ID 10.1.1.2 from server group websg:

# ilbadm remove-server -s server=_sg1.2 sg1

Note the following:

• If the server is being used by a NAT or half-NAT rule, disable the server by using the disable-server subcommand before removal. When a server is disabled, it enters the connection-draining state. After all the connections are drained, the server can be removed by using the remove-server subcommand. After issuing the disable-server command, periodically check the NAT table (by using the show-nat command) to see if the server in question still has connections. After all of the connections are drained (the server does not get displayed in the show-nat command output), the server can then be removed by using the remove-server command.

• If the conn-drain timeout value is set, the connection-draining state will be completed upon conclusion of the timeout period. The default value of conn-drain timeout is 0, meaning it will keep waiting until a connection is gracefully shut down.

How to Re-enable or Disable a Back-End Server

1. Identify the IP address, host name, or server ID of the server you want to re-enable or disable. If a IP address or host name is specified, the server will be re-enabled or disabled for the all rules associated with it. If a server ID is specified, the server will be re-enabled or disabled for the specific rules that are associated to the server ID.

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   Note - A server can have multiple server IDs, if it belongs to multiple server groups.

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2. Re-enable or disable a server.

   # ilbadm enable-server websg.1
   # ilbadm disable-server websg.1

Example 23-5 Re-enabling and Disabling a Back-End Server

In the following example a server with server ID websg.1 is enabled and then disabled.

# ilbadm enable-server websg.1
# ilbadm disable-server websg.1