White Papers

• If there is no unit numbering conict, 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 cong on the losing stack members with its own to synchronize the
conguration 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 oine. Each portion of the split stack
retains the startup and running conguration 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 unaected 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.
Stack Unit and Stack Group Numbering
Enable ports for stacking by specifying a stack-unit number and stack-group number (the stack-unit number stack-group
number command).
• Stack-unit numbers: By default, each switch in Standalone mode is numbered stack-unit 0. Stack-unit numbers are assigned to
member switches when a stack comes up. To pre-congure the units which are the master and standby when the stack boots up, you
can assign unit numbers using the stack-unit renumber command.
• Stack-group numbers: Stacking ports are divided into 16 stack-groups (from 0 to 15), as shown in the following illustration. Each set of
four 10 GbE ports on an Ethernet module or each xed 40 GbE port on the front panel correspond to a stack group. Each stack group
has 40 GbE of bandwidth.
Usage Notes:
• Stacking is not supported on Fibre Channel ports.
• If you use a Fibre Channel module in an S5000 switch, stacking is not supported on Ethernet ports.
• If you use three or more S5000 units in a stack, you can connect up to a maximum of eight 10 GbE ports or two 40 GbE ports in links
between peer switches.
• If you use only two S5000 units in a stack, you can connect up to four 40 GbE ports in links between the two switches.
Stack groups 0 through 11 consist of four 10 GbE ports; stack groups from 12 to 15 consist of one 40G port as follows:
Stack Group
Ports
0 0 to 3
1 4 to 7
2 8 to 11
3 12 to 15
4 16 to 19
5 20 to 23
6 24 to 27
Stacking 909