Dell M6220 User Configuration Manual page 148

1 If you are using the 10G SFP+ ports for stacking, use the CLI or web
interface to configure the ports for stacking. By default, the ports are
configured to operate in Ethernet mode. For more information about
configuring the port mode, see "Stack Port Summary" on page 163 (Web)
or "Configuring Stack Member, Stack Port, and NSF Settings" on page 167
(CLI).
2 For each switch in the stack, connect one cable from a stacking port on the
switch to a stacking port on the next switch.
3 Repeat this process until all of the devices are connected.
4 To complete the ring topology for the stack, connect one stacking port on
the last switch to the remaining stacking port on the first switch.
5 Connect additional cables in parallel for increased stacking bandwidth. Up
to eight ports can be connected in parallel. A minimum of two stacking
links connecting each PCM8024-k to the next stack member is
recommended.
It is strongly recommended to connect the stack in a ring topology for
resiliency against stack link failures.
148
Managing a Switch Stack