Powerconnect B-Series Fcx Hitless Stacking - Dell PowerConnect B-FCXs Configuration Manual

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PowerConnect B-Series FCX hitless stacking

Standby Controller election criteria
The Standby Controller election is based on the following criteria.
1. The highest priority
2. Bootup as Active Controller
3. Bootup as Standby Controller
4. The lowest boot ID
5. The lowest MAC address
Since Standby election candidates must have startup configurations that have been synchronized
with the Active Controller, if the Active Controller does not have a startup-config.txt file, there will
not be a Standby Controller. Once a write memory is performed on the Active Controller, the
startup-config.txt file is written and synchronized to all stack members, and a Standby Controller
can be elected.
PowerConnect B-Series FCX hitless stacking
Hitless stacking is supported on FCX units in an IronStack. It is a high-availability feature set that
ensures sub-second or no loss of data traffic during the following events:
•
•
•
•
During such events, the Standby Controller takes over the active role and the system continues to
forward traffic seamlessly, as if no failure or topology change has occurred. In software releases
that do not support hitless stacking, events such as these could cause most of the units in a stack
to reset, resulting in an impact to data traffic.
The following hitless stacking features are supported:
Hitless stacking switchover – A manually-controlled (CLI-driven) or automatic switchover of the
Active and Standby Controllers without reloading the stack and without any packet loss to the
services and protocols that are supported by hitless stacking. A switchover is activated by the CLI
command stack switch-over. A switchover might also be activated by the CLI command priority,
depending on the configured priority value.
Hitless stacking failover – An automatic, forced switchover of the Active and Standby Controllers
because of a failure or abnormal termination of the Active Controller. In the event of a failover, the
Active Controller abruptly leaves the stack and the Standby Controller immediately assumes the
active role. Like a switchover, a failover occurs without reloading the stack. Unlike a switchover, a
failover generally happens without warning and will likely have sub-second packet loss (packets
traversing the stacking link may be lost) for a brief period of time.
The services and protocols supported by hitless stacking are listed in
Hitless stacking is disabled by default. To enable it, refer to
page 174.
162
Active Controller failure or role change
Software failure
Addition or removal of units in a stack
Removal or disconnection of the stacking cable between the Active and Standby Controllers
Table 37 on page 164.
"Enabling hitless stacking"
PowerConnect B-Series FCX Configuration Guide
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