Notes on environment configuration:
The maximum number of virtual interfaces and logical virtual interfaces that can be defined is 64.
The maximum number of physical interfaces that can be used for redundancy on a single virtual interface is 8 for the Fast switching mode and the GS linkage mode. For the NIC switching mode, the maximum is 2.
The maximum number of logical virtual interfaces that can be defined to a single virtual interface is 63.
The maximum number of characters of each name for physical interfaces (including each VLAN ID for tagged VLAN interfaces) that can be bundled by a virtual interface is 15. When using the name of the interface that exceeds 15 characters, shorten the physical interface name. For details on changing the interface name, see "Linux documentation."
The tagged VLAN interface name is available only by "interface name.VLAN-ID" format, such as eth0.1.
If the interfaces bundled by GLS are not tagged VLAN interfaces, any interfaces that include periods in their names cannot be used.
Set the switches and routers to be connected in order to enable the ARP cache update by GARP response.
In RHEL 8 and later, NetworkManager may update the interface setting file (ifcfg-ethX, route-ethX).
Notes on the operation:
Do not operate a virtual interface and physical interfaces that the virtual interface bundles with a command such as the ip command and the nmcli command while activating the virtual interface.
Do not change the settings with the hanetmask command while activating the virtual interface.
Do not edit the physical interface setting file (ifcfg-ethX) and the virtual interface setting file (ifcfg-shaX), which are used by GLS, while activating the virtual interface.
On the system that makes the transfer route redundant by the Redundant line control function, the user must not start, stop, and restart the network service.
The following messages may be output to the system log during system startup. This does not disrupt ongoing operation.
kernel: Request for unknown module key 'FUJITSU Software: Fujitsu BIOS DB FJMW Certificate: Hexadecimal, forty-digit' err -11 kernel: sha: module verification failed: signature and/or required key missing - tainting kernel kernel: sha: loading out-of-tree module taints kernel.
When performing network maintenance such as restarting or replacing a switch, switch NICs of GLS, stop the monitoring function, or suppress cluster switching in advance not to stop the operation due to a failure in the entire communication path.
Notes on upper applications:
When using TCP in a working application, the data lost when an error occurred in a transfer route is guaranteed by resending from TCP and reaches the other system in the end. Therefore, TCP connection is not disconnected and there is no error in communication. However, it is necessary to set a timer value longer than the time to finish disconnecting/switching a transfer route when an application monitors a response by such as a timer. When TCP connection is disconnected by the reason such as not possible to change a timer value, reestablish the TCP connection and recover the communication.
The data lost at the time of an error in a transfer route is not guaranteed when a working application uses the UDP. It is necessary to execute a recovery process such as sending the data by the application itself.
When using NTP as an upper application, it is necessary to activate an IP address that a Redundant Line Control Function controls before activating an NTP daemon. No special operation is required when activating a system because a Redundant Line Control Function is activated before an NTP daemon. However, when manually activated an IP address with an operation command or when running cluster operation, reactivate an NTP daemon after an IP address is activated. In addition, when using NTP on GLS, a NTP daemon has to be defined to be able to communicate using a logical IP address.
