Administrator Guide

Table Of Contents
Stacking 201
How is the Firmware Updated on the Stack?
When adding a new switch to a stack, the Stack Firmware Synchronization
feature, if enabled, automatically synchronizes the firmware version with the
version running on the stack master per the configuration on the master
switch. The synchronization operation may result in either upgrade or
downgrade of firmware on the mismatched stack member. Use the boot auto-
copy-sw command to enable stack firmware synchronization.
Upgrading the firmware on a stack of switches is the same as upgrading the
firmware on a single switch. After downloading a new image by using the File
Download page or copy command, the downloaded image is distributed to all
the connected units of the stack. For more information about downloading
and installing images, see "Images and File Management " on page 469.
What is Stacking Standby?
The standby unit may be pre-configured or automatically selected. If the
current stack master fails, the standby unit becomes the stack master. If no
switch is pre-configured as the standby unit, the software automatically
selects a standby unit from among the existing stack units.
When the failed master resumes normal operation, it joins the stack as a
member (not as the master) if the new stack master has already been elected.
The stack master copies its running configuration to the standby unit
whenever it changes (subject to some restrictions to reduce overhead). This
enables the standby unit to take over the stack operation with minimal
interruption if the stack master becomes unavailable.
Operational state synchronization also occurs:
when the running configuration is saved to the startup configuration on
the stack master.
when the standby unit changes.
What is Nonstop Forwarding?
Networking devices, such as the Dell Networking N-Series switches, are often
described in terms of three semi-independent functions called the forwarding
plane, the control plane, and the management plane. The forwarding plane
forwards data packets and is implemented in hardware. The control plane is
the set of protocols that determine how the forwarding plane should forward