Dell PowerConnect PC7024 Technical White Paper page 8

Stacking Dell PowerConnect 7000 Series Switches
members of the stack can be powered on sequentially by powering up the switch adjacent to the last
switch powered on.
A stack of units is managed and acts as a single entity when the units are connected together and are
operational. If a unit cannot detect a stacking partner, the unit automatically operates as a stack of 1
with itself as the master. If a stacking partner is detected, the switch always operates in stacking
mode.
When units are operating together as a stack, the following activities occur:
•
All units are checked for firmware version consistency on startup. By default, units
with older versions of firmware are automatically upgraded with the operational
firmware version on the master switch as they join the stack. If a unit has a newer
software version than the master, it is not downgraded to the master's version by
default; however, the administrator can use the following command to enable this
functionality:
console#boot auto-copy-sw allow-downgrade
Before adding a member that has newer version of software to a stack, the
administrator should enable the automatic downgrade feature on the master switch.
•
Switch management and protocols such as OSPF are active only on the master, but
apply to all members of the stack. Unless administratively disabled, the Nonstop
Forwarding (NSF) feature periodically checkpoints the running configuration and the
application state between the master and standby switches during normal stacking
operation. If the master fails, the standby switch takes over operation of the stack.
•
Data forwarding is active on all units in the stack, including the master. Data
forwarding continues to operate should the master become unavailable.
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