Checklist to ensure the proper operation of MultiNICB
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Checklist to ensure the proper operation of MultiNICB

For the MultiNICB agent to function properly, you must satisfy each item in the following list:

• Each interface must have a unique MAC address.
• A MultiNICB resource controls all the interfaces on one IP subnet.
• At boot time, you must plumb all the interfaces that are under the MultiNICB resource and given them test IP addresses.
• All test IP addresses for the MultiNICB resource must belong to the same subnet as the virtual IP address.

  Tip   Solaris-only: The base IP addresses, which the agent uses to test the link status, should be reserved for use by the agent. These IP addresses do not get failed over.

• Solaris-only: The IgnoreLinkStatus attribute is set to 1 (default) when using trunked interfaces.
• If you specify the NetworkHosts attribute, the hosts must be directly accessible on the LAN.
• Solaris-only: Test IP addresses have "nofailover" and "deprecated" flags set at boot time.
• Solaris-only: /etc/default/mpathd/ has TRACK_INTERFACES_ONLY_WITH_GROUPS=yes.
• Solaris-only: If you are not using Solaris in.mpathd, all MultiNICB resources on the system have the UseMpathd attribute set to 0 (default). You cannot run in.mpathd on this system.
• Solaris-only: If you are using Solaris in.mpathd, all MultiNICB resources on the system have the UseMpathd attribute set to 1.
• AIX-only: If any network host is meant to respond to a broadcast ping, run
  no -o bcastping = 1.

Trigger script

MultiNICB monitor agent function calls a VCS trigger in case of an interface going up or down. The following arguments are passed to the script:

• MultiNICB resource name
• device whose status changed (for example, qfe0 for Solaris, en0 for AIX)
• device's previous status (0 for down, 1 for up)
• device's current status and monitor heartbeat

The agent also sends a notification (which may be received via SNMP or SMTP) to indicate that status of an interface changed. The notification is sent using "health of a cluster resource declined" and "health of a clusterresource improved" traps which are mentioned in the VCS User's Guide. A sample mnicb_postchange trigger is provided with the agent. You can customize this sample script as needed or write one from scratch.

The sample script does the following for AIX:

• If interface changes status, it prints a message to the console, for example:

  MultiNICB agent Res. Name: Device en0 status changed from Down to Up.

The sample script does the following for Solaris:

• If interface changes status, it prints a message to the console, for example: MultiNICB: Interface qfe0 came up
• The script saves last IP address-to-interface name association. If any of the IP addresses has been moved, added, or removed, it prints out a message to the console, for example: MultiNICB: IP address 192.4.3.3 moved from interface qfe1:1 to interface qfe0:1

Manually reattach the MultiNICB agent interfaces after failover on AIX

In order to prevent AIX from attempting to send packets through a broken interface (cable unplugged), the MultiNICB agent detaches the interface when it detects that the interface is down. When the interface is brought up (cable plugged in), you need to re-attach the interface to enable the agent to monitor it.

To attach the interface, type:

# chdev -l interface -a state='up'

For example, if the fixed interface is en4, enter:

# chdev -l en4 -a state='up'

Standby interfaces are the ones where the virtual IP is not configured. If a standby interface fails, the current agent does not detach it. Hence, if there are two interfaces within the MultiNICB resource, this can result in a 50% packet loss when the virtual IP address is pinged from within the subnet. No packet loss occurs if the virtual IP address is pinged from outside the subnet.

A workaround for this issue is to manually detach the broken interface and re attach it again after it is fixed.

The command to detach an interface is:

# chdev -l interface -a state='detach'