Ha Overview - 3Com 7757 Configuration Manual

HA C
ONFIGURATION
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HA Overview

The Switch 7758 supports high availability (HA) feature. This feature is to achieve a
high availability of the system and to recover the system as soon as possible in the
event of failures so as to shorten the mean time between failures (MTBF) of the
system.
The functions of HA are mainly implemented by the application running on Fabric
module. A Switch 7758 has two Fabrics which are working in the master-slave
mode: one module works in master mode as the master module, the other works
in slave mode as a backup module. If the master-slave system detects a fault in the
master module, a hot master-slave switchover will be performed automatically.
The slave module will try to connect and control the system bus while the original
master module will try to disconnect with the bus. Thus, the master-slave
switchover of the active system is completed, and at the same time the original
master module is reset to function as the slave module. Therefore, even if the
master module fails, the slave module can also take its role to ensure that the
Switch 7758 runs normally.
The Switch 7758 supports hot swap of Fabrics. The hot swap of master modules
will cause switchover master/slave.
The Switch 7758 supports manually switchover master/slave. You can change the
current module state manually by executing command.
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CAUTION: The HA feature of the Switch 7758 can detect the software upgrade of
the two Fabric with at least one Fabric being active. However, the Fabric and the
I/O Module of the Ethernet switches must be identical in their software version,
otherwise they cannot work normally. So that during the upgrade, you are
recommended to restart the whole switch after the Fabric executes the boot
boot-loader command, to ensure the normal operating of the switch.
The configuration file of the slave module is copied from the master module in real
time, which can ensure that the slave system continues to operate in the same
configuration as that of the original active system after the master-slave
switchover. The Switch 7758 supports automatic synchronization of configuration
file. The active system stores its configuration file and backup the configuration
file to the slave system simultaneously when the master's configuration file is
modified, so as to ensure the consistency of the configurations of the active
system and slave system. And you can also use command to manually synchronize
the configuration file of the master and slave module.
Besides, the system can monitor the power supply and the operating environment
of the system and give timely alarms to avoid the escalation of failures and ensure
safe operations of the system.