User Guide

Stacking 217
Dell EMC Networking N2100-ON Series switches have two fixed stacking
ports in the rear that accept mini-SAS cables. Dell EMC Networking
N3100-ON Series switches support an optional 2x21G or 2x40G stacking
module in the rear slot.
Additional stacking connections can be made between adjacent switch units
to increase the stacking bandwidth provided that all redundant stacking links
have the same port speed. It is strongly recommended that the stacking
bandwidth be kept equal across all stacking connections; that is, avoid mixing
single and double stacking connections within a stack.
It is recommended that operators provision large stacking topologies such
that it is unlikely that a significant portion of the stack capacity will transit
stacking links. One technique for achieving this is to distribute downlinks and
transit links evenly across the stack vs. connecting all downlinks/transit links
to a single stack unit or to adjacent stacking units.
A single switch in the stack manages all the units in the stack (the stack
master), and the stack is managed by using a single IP address. The IP address
of the stack does not change, even if the stack master changes.
A stack is created by daisy-chaining stacking links on adjacent units. If
available, up to eight links per stack unit can be used for stacking (four in
each direction). A stack of units is manageable as a single entity when the
units are connected together. If a unit cannot detect a stacking partner on any
port enabled for stacking, the unit automatically operates as a standalone
unit. If a stacking partner is detected, the switch always operates in stacking
mode. One unit in the stack is designated as the stack master. The master
manages all the units in the stack. The stack master runs the user interface
and switch software, and propagates changes to the member units. To manage
a stack using the serial interface, the administrator must connect to the stack
master via the connect command or by physically connecting the cable to the
stack master.
A second switch is designated as the standby unit, which becomes the master
if the stack master is unavailable. The unit to be selected as the standby can
be manually configured, or the system can select the standby automatically.
When units are in a stack, the following activities occur:
• All units are checked for software version consistency.