3Com Switch 7750 Configuration Guide Guide

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HA CONFIGURATION
HA Overview 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 Switch
Fabric board. A Switch 7758 has two Switch Fabrics which are working in the
master-slave mode: one board works in master mode as the master board, the
other works in slave mode as a backup board. If the master-slave system detects a
fault in the master board, a hot master-slave switchover will be performed
automatically. The slave board will try to connect and control the system bus while
the original master board 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 board is reset to function as the slave board. Therefore, even if
the master board fails, the slave board can also take its role to ensure the normal
operation of Switch 7758.
Switch 7758 supports hot swap of Switch Fabrics. The hot swap of master boards
will cause switchover master/slave.
Switch 7758 supports manually switchover master/slave. You can change the
current board state manually by executing command.
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CAUTION: The HA feature of the Switch 7758 Switches can realize the software
upgrade of the two Switch Fabric with at least one Switch Fabric being active.
However, the Switch 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
Switch Fabric executes the boot boot-loader command, to ensure the normal
operating of the switch.
The configuration file of the slave board is copied from the master board 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. 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 board.
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.