Configuring the netmon.cf file

The netmon.cf file is an optional configuration file that customers can use to augment the ping operation on the available target hosts on the network. The target hosts that are not defined to be part of the cluster are not available from the cluster nodes. The target hosts can be accessed from the IP addresses being monitored by topology services.

If you are running a single-node or two-node cluster, you must configure netmon.cf file to detect the network interface failures.

PowerHA® SystemMirror® periodically attempts to contact each network interface in the cluster. If the attempt to contact an interface fails on one node of a two-node cluster, the corresponding interface on the other node is also flagged as an Offline node. The other node is flagged as an Offline node because it does not receive a response from the peer cluster node. To avoid such behavior, the PowerHA SystemMirror must be configured to contact a network instance outside of the cluster. You can use the default gateway of the subnet from which the PowerHA SystemMirror GUI is used.

To configure the netmon.cf file, complete the following steps:
  1. Configure the netmon.cf file to check the status of the network monitored by the virtual switch.
  2. On each node, create the following file: /var/ct/cfg/netmon.cf
    Note: Each line of netmon.cf file contains the system name or the IP address of the external network instance. IP addresses can be specified in the dotted decimal notation.

Example of the netmon.cf file

The following example shows the configuration result for the netmon.cf file.
#This is default gateway for all interfaces in the subnet 192.168.1.0 
192.168.1.1

If you are using the Virtual I/O Server (VIOS), the configuration test becomes unreliable because the netmon.cf file cannot determine whether the inbound traffic is received from the VIOS or a client. The LPAR cannot distinguish a virtual adapter and a real adapter. To address this problem, the netmon library supports up to 32 targets for each local network adapter. If the ping operation for any of these targets is successful, the local adapter is considered to be in an Online state. The targets can be specified in the netmon.cf file with the !REQD keyword. For example:

!REQD <owner><target>
The targets can be also specified in the netmon.cf file by entering the following command: 
!IBQPORTONLY !ALL

Location

/var/ct/cfg/netmon.cf
Location of the netmon.cf file in a PowerHA SystemMirror environment.