PRIMECLUSTER Global Link Services Configuration and Administration Guide: Redundant Line Control Function 4.2 (for Linux)

2.2.6.1 HUB monitoring function

The HUB monitoring function issues the ping command to adjacent HUB at regular intervals and switches the interface to be used when a line failure is detected. Up to two HUBs can be registered per virtual interface. This function is available exclusively for NIC switching mode.

This function can also monitor a transfer path between two HUBs (this is called HUB-to-HUB monitoring function). HUB-to-HUB monitoring function detects a failure between two HUBs. This function can thus prevent a communication error from occurring due to NIC switching when a HUB-to-HUB failure occurs.

If the standby patrol function is used, the HUB-to-HUB monitoring is not required because the standby patrol function is comprised with HUB-to-HUB monitoring function. (See section "2.2.7 Standby patrol function")

Figure 2.18 shows an outline of the HUB monitoring function

[Figure 2.18 HUB monitoring function]

If a hub cannot have an IP address, IP address of a host or a router that is connected to the hub can be monitored. However, if the monitored host or router stops, polling the host or router fails and a NIC switching event might occur. In order to prevent an unnecessary switching process, it is recommended to set up two monitoring targets, as well as enabling HUB-to-HUB monitoring function in case one of the monitoring targets stops.

• Refer to "7.7 hanetpoll Command" for configuration of HUB-to-HUB monitoring feature.
• It is not recommended to operate with a single HUB. It is possible to have only one configuration for a remote end when using a single HUB. However, it defeats the purpose of multiplexing transfer paths if the HUB breaks.

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2.2.6.1.1 Not using HUB-to-HUB monitoring feature

2.2.6.1.2 Using HUB-to-HUB monitoring feature