White Papers

Adding a Configured Unit to an Existing Stack
To add a configured unit to an existing stack, use the following commands.
If a stack unit goes down and is removed from the stack, the logical provisioning configured for that stack-unit number is saved
on the master and standby units. When a new unit is added to the stack, if a stack group configuration conflict occurs between
the new unit and the provisioned stack unit, the configuration of the new unit takes precedence.
1. Add the configured unit to the top or bottom of the stack.
2. Power on the switch.
3. Attach cables to connect ports on the added switch to one or more existing switches in the stack.
Dell EMC Networking OS automatically assigns a number to the new unit and adds it as member switch in the stack. The
new unit synchronizes its running and startup configurations with the stack.
Dell EMC Networking OS Behavior: When you add a switch to a stack
● If you configure the new unit with a stack number that is already assigned to a stack member, the stack avoids a numbering
conflict by assigning the new switch the first available stack number.
● If the stack has been provisioned for the stack number that is assigned to the new unit, the pre-configured provisioning
must match the switch type. If there is a conflict between the provisioned switch type and the new unit, a mismatch error
message is displayed.
Merge Two Stacks
You may merge two stacks while they are powered and online.
To merge two stacks, connect one stack to the other using the mini-SAS cables from the stacking ports.
● Dell EMC Networking OS selects a master stack manager from the two existing managers based on the priority of the stack.
● Dell EMC Networking OS resets all the units in the losing stack; they all become stack members.
● If there is no unit numbering conflict, the stack members retain their previous unit numbers. Otherwise, the stack manager
assigns new unit numbers, based on the order that they come online.
● The stack manager overwrites the startup and running config on the losing stack members with its own to synchronize the
configuration on the new stack members.
Split a Stack
To split a stack, unplug the desired stacking cables.
You may do this at any time, whether the stack is powered or unpowered, and the units are online or offline. Each portion of the
split stack retains the startup and running configuration of the original stack.
For a parent stack that is split into two child stacks, A and B, each with multiple units:
● If one of the new stacks receives the master and the standby management units, it is unaffected by the split.
● If one of the new stacks receives only the master unit, that unit remains the stack manager, and Dell EMC Networking OS
elects a new standby management unit.
● If one of the new stacks receives only the standby unit, it becomes the master unit of the new stack, and Dell EMC
Networking OS elects a new standby unit.
● If one of the new stacks receives neither the master nor the standby management unit, the stack is reset so that a new
election can take place.
Stacking Configuration Tasks
Following are the stacking configuration tasks:
● Assigning Unit Numbers to Units in a Stack
● Creating a Virtual Stack Unit in a Stack
● Displaying Information About a Stack
● Influencing Management Unit Selection on a Stack
● Managing Redundancy on a Stack
● Resetting a Unit on a Stack
● Recover from Stack Link Flaps
842
Stacking