Technical data

FastIron Ethernet Switch Administration Guide 105
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Hitless management on the FSX 800 and FSX 1600
3
When control protocols are synchronized and protocol synchronization timers expire, the standby
management module will be in hot-standby mode, meaning the standby module is ready to take
over as the active management module. In the event of a switchover, the standby module will pick
up where the active module left off, without interrupting data traffic.
After baseline synchronization, any new events that occur on the active CPU will be dynamically
synchronized on the standby CPU. Examples of such events include:
• CLI/HTTP/SNMP configurations
• CPU receive packets
• Link events
• Interrupts
• Layer 2 and Layer 3 forwarding table updates
• Dynamic user authentication updates such as 802.1X or multi-device port authentication
• Routing protocols OSPFv2 and OSPFv3 updates if NSR is enabled.
Dynamic events are synchronized in such a way that if the active CPU fails before fully executing an
event, the standby CPU (newly active CPU) will execute the event after the failover. Also, if the active
CPU aborts the event, the standby CPU will abort the event as well.
NOTE
Since both the standby and active management modules run the same code, a command that
brings down the active management module will most likely bring down the standby management
module. Because all configuration commands are synchronized from active to standby
management module in real time, both management modules will reload at almost the same time.
This in turn will cause the system to reset all interface modules (similar to the behavior when the
reboot command is executed) and will cause packet loss associated with a system reboot.
NOTE
If the new active management module becomes out-of-sync with an interface module, information
on the interface module can be overwritten in some cases, which can cause an interruption of traffic
forwarding.
How a Hitless switchover or failover impacts system functions
Fora description of the feature’s impact to major system functions, refer to Table 15 on page 101.
Enabling hitless failover on the FSX 800 and
FSX 1600
Hitless failover is disabled by default. When disabled, the following limitations are in effect:
• If a failover occurs, the system will reload. The following message will display on the console
prior to a reload.
STBY:- - - - Active Hitless Failover is disabled. Re-setting the system - -
• Manual switchover (CLI command switch-over-active-role) is not allowed. If this command is
entered, the following message will display on the console:
Switch-over is not allowed. Reason: hitless-failover not configured.