In Virtual NIC mode, two methods in the table below are available to monitor the network status to which a physical interface is connected.
Monitoring type | Monitoring method |
|---|---|
HUB monitoring | A ping command is sent periodically to the switch/HUB to which the NIC is connected to check whether the device responds normally. |
Standby patrol | An Ethernet frame for monitoring is sent periodically from the standby NIC to the active NIC to check the status of the transfer path between the standby and the active NICs. |
The network monitoring function is available by any of the following combination. It is not possible to use this function with only HUB monitoring.
HUB monitoring and standby patrol
Only standby patrol
The network monitoring function combines two different types of monitoring inhibit unnecessary switching of transfer paths. For example, if only HUB monitoring detects an error while the standby patrol is normal, this means that the both active NICs and the standby NICs are normal, so the failover of transfer paths is inhibited. Failovers are performed only when both monitoring functions detect an error.
Figure 2.43 Network monitoring function
Point
When a link down occurs due to an NIC malfunction, a failover is performed immediately by link status monitoring.
If automatic fail-back is enabled, after any failover, operation will switch back to the original NIC as soon as the standby patrol detects that the network has recovered.
After the route is switched to the standby side due to failure detection in case that a communication route failure is also detected in the standby side, switch back to the original NIC automatically.
If the settings are incorrect as follows, the HUB monitoring function detects a route error even communication with the monitoring destination IP address is enabled.
The network segment is not consistent between the IP address of the monitoring target and the IP address of the virtual interface.
Communication with the IP address of the monitoring target is enabled by other interfaces except the virtual interface of GLS.
An error in the settings can be found earlier when a route error is detected. However, an error cannot be detected in the following environments:
OS is RHEL7.
IPv6 is used as the monitoring destination IP address.
