Users Guide

Switch Feature Overview 65
Single IP Management
When multiple switches are connected together through the stack ports, they
operate as a single unit with a larger port count. The stack operates and is
managed as a single entity. One switch acts as the primary, and the entire
stack is managed through the management interface (Web, CLI, or SNMP)
of the stack primary.
Primary Failover with Transparent Transition
The stacking feature supports a standby or backup unit that assumes the
stack primary role if the stack primary fails. As soon as a stack primary failure
is detected, the standby unit initializes the control plane and enables all other
stack units with the current configuration. The standby unit maintains a
synchronized copy of the running configuration for the stack.
Nonstop Forwarding on the Stack
The Nonstop Forwarding (NSF) feature allows the forwarding plane of stack
units to continue to forward packets while the control and management
planes restart as a result of a power failure, hardware failure, or software fault
on the stack primary and allows the standby switch to quickly takeover as the
primary.
Hot Add/Delete and Firmware Synchronization
Units can be added to and deleted from the stack without cycling the power
on the stack. Units to be added to the stack must be powered off prior to
cabling into the stack to avoid election of a new primary unit and a possible
downgrade of the stack. When the newly added unit is powered on, the Stack
Firmware Synchronization feature, if enabled, automatically synchronizes the
firmware version with the version running on the stack primary. The
synchronization operation may result in either an upgrade or a downgrade of
firmware on the mismatched stack member. Once the firmware is
synchronized on a member unit, the running-config on the member is
updated to match the primary switch. The startup-config on the standby and
member switches is not updated to match the primary switch due to
configuration changes on the primary switch. Saving the startup config on the
primary switch also saves it to the startup config on all the other stack