Hitless Stacking; Hitless Stacking Overview; Hitless Stacking Behavior - Arris Ruckus ICX 7850 Series Configuration Manual

Hitless Stacking

• Hitless stacking overview..........................................................................................................................................171
• Hitless stacking behavior..........................................................................................................................................171
• Supported hitless stacking events ..........................................................................................................................173
• Non-supported hitless stacking events.................................................................................................................. 173
• Supported hitless stacking protocols and services............................................................................................... 173
• Hitless stacking configuration notes and feature limitations.............................................................................. 176
• What happens during a hitless stacking switchover or failover.......................................................................... 176
• Standby controller role in hitless stacking............................................................................................................. 177
• Support during stack formation, stack merge, and stack split............................................................................ 178
• Hitless stacking failover............................................................................................................................................ 181
• Hitless stacking switchover...................................................................................................................................... 182
• Displaying information about hitless stacking...................................................................................................... 187
• Syslog messages for hitless stacking failover and switchover.............................................................................189

Hitless stacking overview

Hitless stacking is supported on FastIron units in a stack. It is a High Availability feature set that ensures little or no loss of data
traffic during the following events:
• 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 controller and the standby controller
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, affecting data traffic.
FastIron stackable units support the following hitless stacking features:
Hitless stacking switchover - A manually-controlled (CLI-driven) or automatic switchover of the active controller and standby
controller 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 command. A switchover may also be activated by the
priority command, depending on the configured priority value.
Hitless stacking failover - An automatic, forced switchover of the active controller and standby controller because of a failure or
abnormal termination of the active controller. During a failover, the active controller abruptly leaves the stack, and the standby
controller immediately assumes the active role. As with a switchover, a failover occurs without the stack being reloaded. Unlike a
switchover, a failover generally occurs without warning and is likely to result in packet loss for up to a few seconds (packets
traversing the stacking link may be lost).
Hitless stacking failover is enabled by default beginning with Fastiron release 08.0.20.

Hitless stacking behavior

Hitless stacking is enabled by default for FastIron release 08.0.20 and later releases. In previous releases, the hitless-failover
command must be set to enable in the configuration.
Ruckus FastIron Stacking Configuration Guide, 08.0.90
Part Number: 53-1005572-01 171