Brocade FastIron Ethernet Switch Stacking Configuration Guide - Manual (Page 105)

over as the active controller. In the event of a switchover, the standby controller will pick up where the
active module left off, without interrupting data traffic.
After baseline synchronization, any new events that occur on the active controller will be dynamically
synchronized on the standby controller. Examples of such events include:
• CLI, HTTP, and SNMP configurations
• Link events
• Interrupts
• Layer 2 and Layer 3 forwarding table updates
• Dynamic user authentication updates such as 802.1X or multi-device port authentication
After a switchover, the new active controller receives updates from the stack members and sends
verification information to the stack members to ensure that they are synchronized.
NOTE
The events described previously occur internally and do not create or affect the external network
topology.
NOTE
If there is no active controller after a reload, the bootup standby assumes the active role in
approximately 60 seconds without a reload. A bootup standby is the device that was the standby
controller before the reload. It may not be the current standby controller.
Standby controller role in hitless stacking
In software releases that do not support hitless stacking, the standby controller functions as a dummy
device, meaning it provides limited access to the CLI, such as show, stack, and a few debug
commands. The active controller can access the full range of the CLI. The standby controller
synchronizes its configuration with the active controller at each reset.
With the introduction of hitless stacking, the standby controller shadows the active controller. The role or
behavior of the standby controller with hitless stacking is as follows:
• The local console on the standby controller still accepts only show, stack, and a few debug
commands.
• The runtime configuration on the standby controller is synchronized with the active controller
whenever there is a configuration change.
• Protocols are configured in the runtime configuration, but no protocol packets are sent out on the
standby.
• The state of every unit is known, including the state of the active controller. The show commands
will display current information, such as STP or port states.
• When a failover occurs, the standby controller will use its current runtime configuration. The
configuration could be different from the active controller if the last configuration transmission was
lost.
• After a failover, the new active controller (old standby) programs all other units in hardware, based
on its runtime configuration.
Standby controller election
Candidates for standby controller must meet the following criteria:
• The unit is operational and the image and module configuration match that of the active controller.
• The runtime configuration matches that of the active controller.
Standby controller role in hitless stacking
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