DELL N3000 User Manual

Managing a Switch Stack

• If the switch you add does not have an assigned unit number, then the 

switch sets its configured unit number to the lowest unassigned unit 

number. 

• If the unit number is configured and there are no other devices using the 

unit number, then the switch starts using the configured unit number. 

• If the switch detects that the maximum number of units already exist in 

the stack making it unable to assign a unit number, then the switch sets its 

unit number to 

unassigned and does not participate in the stack.

When adding a new member to a stack, make sure that only the stack cables, 

and no network cables, are connected before powering up the new unit. Stack 

port configuration is stored on the member units. If stacking over Ethernet 

ports (N4000 only), configure the ports on the unit to be added to the stack as 

stacking ports and power the unit off prior to connecting the stacking cables. 

Make sure the links are not already connected to any ports of that unit. This is 

important because if STP is enabled and any links are UP, the STP 

reconvergence will take place as soon as the link is detected. 
After the stack cables on the new member are connected to the stack, you can 

power up the new units, beginning with the unit directly attached to the 

currently powered-up unit. Always power up new stack units closest to an 

existing powered unit first. Do not connect a new member to the stack after it 

is powered up. Also, do not connect two functional, powered-up stacks 

together. Hot insertion of units into a stack is not supported.
If a new switch is added to a stack of switches that are powered and running 

and already have an elected stack master, the newly added switch becomes a 

stack member rather than the stack master. Use the boot auto-copy-sw 

command on the stack master to enable automatic firmware upgrade of newly 

added switches. If a firmware mismatch is detected, the newly added switch 

does not fully join the stack and holds until it is upgraded to the same 

firmware version as the master switch. After firmware synchronization 

finishes, the running configuration of the newly added unit is overwritten 

with the stack master configuration. Stack port configuration is always stored 

on the local unit and may be updated with preconfiguration information from 

the stack master when the unit joins the stack.